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Originally Published 12 April 2021
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Dietary Magnesium Insufficiency Induces Salt-Sensitive Hypertension in Mice Associated With Reduced Kidney Catechol-O-Methyl Transferase Activity

Asako Kumagai, Satoru Takeda, Eisei Sohara, Shinichi Uchida, Hiroshi Iijima https://orcid.org/0000-0001-8402-0292, Astuo Itakura https://orcid.org/0000-0002-4554-164X, Daisuke Koya, and Keizo Kanasaki https://orcid.org/0000-0002-9563-502X [email protected]Author Info & Affiliations
Hypertension
Volume 78, Number 1
https://doi.org/10.1161/HYPERTENSIONAHA.120.16377
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VIEW EDITORIAL:Mg2+ Channels as the Link Between Mg2+ Deficiency and COMT Downregulation in Salt-Sensitive Hypertension

Graphical Abstract

Abstract

COMT (Catechol-O-methyl transferase), an enzyme that metabolizes catechol, requires magnesium (Mg2+) to maintain its activity. Low COMT activity causes insufficient 2-methoxyestradiol (2-ME), a biologically active metabolite from hydroxyestradiol, which leads to hypertensive disorders, including preeclampsia. Hypoestrogenism increases the risk of salt-sensitive hypertension (SSH). SSH and preeclampsia are risk factors for each other; however, the molecular mechanism of this interaction is unclear. We focused on the interactive effect of Mg2+ insufficiency and genetic COMT deficiency on SSH using 2 strains of mice with genetically distinct COMT activity. In male mice, BL6 (C57BL/6J), a high-activity COMT strain, displayed unaltered blood pressure regardless of the Mg2+ and salt levels in food; DBA (DBA/2J), a low-activity COMT strain, developed SSH under low Mg2+ and high-salt conditions. COMT inhibition in C57BL/6J strain also induced SSH. Treatment with 2-ME ameliorated SSH in both models. The ATR1 (angiotensin II type 1 receptor)–STE20-SPAK (serine-proline alanine-rich kinase)–NCC (sodium chloride cotransporter) axis, molecules associated with sodium reabsorption in distal convoluted tubules, was activated in mice that developed SSH. In female DBA mice, ovariectomized mice displayed SSH under low Mg2+ associated with activation of ATR1-SPAK-NCC axis; 2-ME inhibited all, whereas the blood pressure of sham mice was unaltered regardless of any intervention. Our findings revealed that Mg2+ insufficiency exaggerated the low COMT activity and induced SSH via the ATR1-SPAK-NCC axis due to 2-ME insufficiency, suggesting a new pathophysiological role that links COMT/2-ME deficiency with hypertensive syndrome.

Introduction

See Editorial, pp 151–154
COMT (catechol-O-methyl transferase), a magnesium-dependent enzyme, metabolizes catechols such as catecholamine and hydroxyestradiol. The compound 2-methoxyestradiol (2-ME), an estrogen metabolite of COMT generated from hydroxyestradiol, is a biologically active compound that improves glucose/lipid metabolism and possesses anti-inflammatory, antivasoconstrictive, antiangiogenic, and antitumor effects.1,2 COMT activity is determined by various factors, as described in Figure 1A. Among genetic factors, single nucleotide polymorphisms, which determine the stability of the COMT protein, are the best-known factors. In humans, rs4680 (Val158Met) is a common polymorphism in which Val/Val possesses 3× to 4× higher COMT activity than Met/Met3 (Figure 1A), and low activity of COMTmet/met has been linked to an increased risk of hypertension4 and acute coronary syndrome.5 Haplotype sequences are also widely investigated, as in patients with preeclampsia in which haplotypes related to low COMT activity were reported to have a significantly higher risk of preeclampsia recurrence6 (Figure 1A). These reports illustrate the global importance of COMT deficiency in the onset of hypertensive syndrome in humans.
Figure 1. Mg2+ deficiency induced salt-sensitive hypertension only in the DBA (DBA/2J) mice under high-salt conditions and 2-methoxyestradiol (2-ME) normalized systolic BP. A, COMT (catechol-O-methyl transferase) scheme and the association between COMT activity and Mg2+ concentration. COMT is an enzyme that methylates catechol. S-adenosyl-methionine (SAM) is the methyl donor for COMT, and the demethylated compound S-adenosyl-homocysteine (SAH) is known as an endogenous inhibitor of COMT. Genetic factors such as single nucleotide polymorphisms and haplotypes determine the strength of COMT activity. Mg2+ is a cofactor of COMT and keeps its active site open. An estrogen catechol, 2-hydroxyestradiol, is metabolized by COMT to 2-ME, which is known for several bioactivities, including preventing the development of preeclamptic phenotypes. The right graph represents rat COMT activity that was directly proportional to Mg2+ concentration. The horizontal axis represents the concentration of Mg2+ in an enzyme reaction mixture. The vertical axis represents the enzyme activity in reaction number in a minute. In this experiment, the reaction number of 8 min-1 corresponds to 19.2 µmol/L of normetanephrine produced in 15 min from 1 mmol/L norepinephrine. B, Scheme of the Mg2+-deficient high-salt protocol for the BL6 (C57BL/6J) and DBA mice. Mice were fed 0.1% Mg2+/0.03% Mg2++0.6% NaCl diet from wk 0. For some mice, 0.6% NaCl diets were replaced with 8% NaCl diets without changing the Mg2+ concentration in the diet at wk 2, and 2-ME was injected intraperitoneally from wk 3. C, Body weight (BW) at wk 5. N=5 in each group. D, Plasma Mg2+ concentration at wk 5. N=3 in DBA 0.1% Mg2+ group and DBA 0.03% Mg2+ group, and N=4 in the other groups. E, Twenty-four–hour urinary Mg2+ excretion. N=3 in BL6 0.1% Mg2+ high-salt 2-ME group, DBA 0.1% Mg2+ high-salt 2-ME group and DBA Mg2+ 0.03% high-salt 2-ME group, N=4 in the other groups. F, Weekly systolic BP and systolic BP at wk 5 of BL6 and DBA. High salt was administered at wk 2, and 2-ME treatment started at wk 3. N=5 in each group. The graph is expressed as the mean±SEM. BP indicates blood pressure; HS, high salt or 8% NaCl; and NS, nonsignificant. The significance was determined by 3-way ANOVA for comparisons within one strain or by t test for comparison between 2 strains and is represented as *P<0.05 or **P<0.01.
Magnesium (Mg2+) is also an essential factor that induces the correct conformation of the active site of the enzyme7 (Figure 1A). Mg2+ is the second most abundant intracellular cation and functions as a cofactor of over 300 enzymes and activator of ≈200 enzymes.8 Mg2+ deficiency has been suggested to have roles in development of various diseases, such as cardiovascular disease, arrhythmia, hypertension, neurodegenerative disease, migraine, epilepsy, and metabolic disorders, such as type 2 diabetes and lipid metabolism disorder.9 Moreover, magnesium sulfate (MgSO4) is known to reduce the risk of eclampsia and maternal death of patients with preeclampsia,10 possibly through the reduction of oxidative stress and the vasoconstrictive effect of AII (angiotensin II) and endothelin-1 in the human placenta11,12; thus, Mg2+ deficiency might have an essential role in the development of preeclampsia.
Mice with 2-ME insufficiency due to genetic COMT defects present a preeclamptic phenotype,13 and COMT activities and plasma 2-ME levels were significantly suppressed in patients with preeclampsia compared with healthy pregnant women.6,13 With regard to the long-term complications of preeclampsia, women with a history of preeclampsia are more prone to develop salt-sensitive hypertension (SSH) before menopause.14 SSH is recognized as an estrogen-related disease based on reports of an increased risk of SSH in postmenopausal women and young women with primary ovarian insufficiency15,16 and the positive effect of estrogen replacement therapy on ovariectomized mice and rats that developed SSH.17,18 A link between COMT and SSH has been proposed: high salt reduced COMT activity and induced SSH via the accumulation of norepinephrine19; however, the effect of COMT as an estrogen metabolizer has never been discussed.
One of the best-known mechanisms of SSH is hyperactivation of the NCC (sodium chloride cotransporter), a thiazide-sensitive salt absorptive pathway localized at distal convoluted tubules. NCC is responsible for the reabsorption of 5% to 10% of filtered NaCl and is a fine regulator of Na+ homeostasis.20 NCC activation is regulated by with no lysine kinase (WNK)/STE20-SPAK (serine-proline alanine-rich kinase)/NCC phosphorylation cascade, which is activated by AII-induced ATR1 (angiotensin II type 1 receptor) upregulation.21,22 We previously identified that ATR1 upregulation was induced by COMT deficiency in the aorta23; therefore, we hypothesized that COMT might regulate NCC via the ATR1-SPAK axis.
Given the essential role of Mg2+ on COMT activity24–26 as well as the link between COMT deficiency and preeclampsia/SSH, we hypothesized that COMT deficiency is a shared molecular mechanism of preeclampsia and SSH and that Mg2+ deficiency cast a negative influence over these diseases.

Materials and Methods

Data that support the findings of this study are available from the corresponding author upon reasonable request. A detailed section of methods and materials is provided in the Data Supplement.

Summary

In vitro experiment of the effect of Mg 2+ on COMT activity was performed using the methods established in the previous reports.27,28 All animal experiments were approved by the Institutional Animal Care and Use Committee of Kanazawa Medical University (protocol numbers 2017-120 and 2019-17) and by the Institutional Animal Care and Use Committee of Shimane University (protocol number IZ2-52).
All experiments are performed according to Japanese guidelines and institutional ethics committee guidelines. For Mg2+-deficient experiment, 7 weeks old male/female DBA (DBA/2J) and male BL6 (C57BL/6J) were fed 0.6% NaCl diet with either 0.1% Mg2+ or 0.03% Mg2+, part of which were replaced with 8% NaCl diet with the same Mg2+ concentration after 2 weeks. For COMT inhibitor (COMTi) experiment, male BL6 mice were treated with COMTi Ro41-0960 (25 mg/kg per day) or grapeseed oil intraperitoneally from the week when 0.1% Mg2+ diet was given. Intraperitoneal injection of either 2-ME (10 ng/day), hydrochlorothiazide (25 mg/kg per day), or PBS was administered from 10 weeks of age. For female mice, ovariectomy was performed at 7 weeks of age before the diet was replaced with 0.1% Mg2+ or 0.03% Mg2+ diet. All mice were euthanized at 12 weeks of age. Blood pressure (BP) was measured every week by tail-cuff system as previously described.23 Plasma was collected for analysis of electrolytes, AII, catecholamine, S-adenosyl-L-methionine, S-adenosyl-L-homocysteine, and 17-β estradiol (E2) concentrations. Plasma catecholamine, S-adenosyl-L-methionine, and S-adenosyl-L-homocysteine were analyzed, as previously described.28–31 Twenty-four–hour urine was collected for analysis of electrolytes and albumin to creatinine ratio. Western blot analysis was performed using whole kidney extraction. Kidney COMT activity was measured using methyltransferase activity kit.

Statistical Analysis

The data are presented as the mean±SE. For analysis of differences among group means, either 2-way ANOVA or 3-way ANOVA followed by Tukey test was used depending on the number of variances. For comparison between 2 groups, Student t test was used. P<0.05 was considered significant. Graph Pad Prism software 8.2.1 (La Jolla, CA) was used for statistical analysis.

Results:

COMT Activity Was Regulated by Mg2+ Concentration

Enzymatic activity of rat COMT protein was evaluated under different Mg2+ concentrations by measuring the conversion ratio of norepinephrine to normetanephrine in vitro. The COMT activity was directly proportional to Mg2+ concentration (Figure 1A).

Plasma Mg2+ Concentration Decreased With Dietary Mg2+ Insufficiency

Similar to single nucleotide polymorphism–dependent human COMT activity, mouse COMT activity exhibits variation among strains.32 Different mRNA isoforms exist among mouse strains, in which mice with short proximal 3′ untranslated region isoforms, such as BL6 mice, are known to have greater COMT activity and protein expression than mice with the original length of the 3′ untranslated region, such as DBA mice.33 This study utilizes these 2 strains, BL6 and DBA, with high and low COMT activities to evaluate the effect of Mg2+ on COMT activity. The scheme of the study protocol is illustrated in Figure 1B. Mouse growth was not affected by the concentrations of Mg2+ or NaCl in either strain (Figure 1C). Under basal conditions, the level of plasma Mg2+ was significantly lower in the DBA strain than in the BL6 strain, and the plasma levels were decreased directly proportionally to the amount of Mg2+ contained in the diet in both strains regardless of the NaCl concentration (Figure 1D). Urinary Mg2+ excretion also decreased as Mg2+ intake decreased in both strains (Figure 1E). In the BL6 mice, the basal level of urinary Mg2+excretion was higher trend than that in the DBA mice and was not affected by a high-salt load (Figure 1E). However, in the DBA mice, urinary Mg2+ excretion increased to the higher level than that of BL6 mice by high-salt load, and it was significantly higher when they were fed Mg2+-deficient diet (Figure 1E).

Mg2+ Deficiency Induced Salt-Sensitive Hypertension in the DBA Mice; 2-ME Ameliorated This Condition

The systolic BP (sBP) values without interventions were comparable between the strains. The sBP of BL6 was not affected by Mg2+ deficiency or high salt (Figure 1F). The sBP of DBA was not significantly affected by Mg2+ deficiency or high salt alone but was significantly increased in the Mg2+-deficient and high-salt conditions. Administration of 2-ME normalized the sBP (Figure 1F) in the DBA mice fed Mg2+-deficient and high-salt diet. The plasma AII level was higher trend in the BL6 mice than in the DBA mice. High salt decreased the plasma AII level in both mice strains, especially in DBA mice (Figure S1 in the Data Supplement). Fluid and Na+ balances could not directly explain the SSH developed in these mice (Figures S2 and S3). At basal condition, DBA mice exhibited significantly lower kidney COMT activity than BL6 mice. Under low Mg2+ and high-salt condition, difference in kidney COMT activities between 2 strains became more significant. 2-ME did not restore the COMT activity (Figure S4A through S4D). Mg2+ deficiency tended to increase the plasma norepinephrine and epinephrine levels compared to those in the normal Mg2+ mice only in DBA mice (Figure S5A and S5B). No alternation was found in plasma levels of both S-adenosyl-L-methionine and S-adenosyl-L-homocysteine in the high-salt–loaded mice regardless of the Mg2+status (Figure S5C and S5D).

Chemical Inhibition of COMT Activity Induced Salt-Sensitive Hypertension in the BL6 Mice; 2-ME Ameliorated This Condition

To confirm the relevance of the COMT deficiency in the onset of SSH, we administered a COMTi to high-salt–loaded, normal-Mg2+ BL6 mice (Figure 2A). The body weight and plasma Mg2+ concentration were not different among all groups (Figure 2B and 2C). The sBP did not change by COMTi alone, but coadministration with high salt significantly increased the sBP, which was normalized by 2-ME (Figure 2D). Both Δwaterintake-urine and Δ Na+intake-urine were significantly increased by high-salt load, but urinary Mg2+ excretion and % Na+ excretion were unaltered as described in detail in Figure S6.
Figure 2. Chemical inhibition of COMT (catechol-O-methyl transferase)-induced and 2-methoxyestradiol (2-ME)–ameliorated salt-sensitive hypertension in normal Mg2+ BL6 (C57BL/6J) mice under high-salt conditions. A, Schemes of the COMT inhibitor (COMTi) high-salt BL6 protocol. Mice were fed 0.1% Mg2+ 0.6% NaCl diet from wk1. COMTi was administered intraperitoneally from wk 1. For some mice, 0.6% NaCl diet was replaced with 8% NaCl diet at wk 2, and 2-ME was injected intraperitoneally from wk 3. B, Body weight (BW) at wk 5. N=7 in each group. C, Plasma Mg2+ concentration at wk 5. N=4 in each group. D, Weekly systolic BP and systolic BP at wk 5. N=7 in each group. BP indicates blood pressure; HS, high salt or 8% NaCl. The graph shows the mean±SEM. The significance was determined by three-way ANOVA and is represented as **P<0.01.

Kidney NCC Was Activated via ATR1-SPAK Activation in the High-Salt–Loaded Mg2+-Deficient DBA Mice and COMTi-Treated BL6 Mice

p-NCC (phosphorylated NCC) forms a complex-glycosylated homodimer with a molecular mass of ≈310 kDa, and this is the only form that can exist on the plasma membrane.34 To identify p-NCC as a homodimer, we prepared protein extracts dissolved in 8 M urea in which protein complexes resist dissolution.35 In the DBA mice, a high-salt load increased the expression of ATR1 and activation of both SPAK and NCC (phosphorylated SPAK and NCC) only in the Mg2+-deficient conditions (Figure 3A). COMTi treatment of the BL6 mice had a similar effect on increasing the ATR1-NCC-SPAK axis under the high-salt condition (Figure 3B). The upregulation of ATR1-SPAK-NCC axis was suppressed by 2-ME in both SSH models (Figure 3A and 3B).
Figure 3. High salt activated the ATR1 (angiotensin II type 1 receptor)-SPAK (serine-proline alanine-rich kinase)-NCC (sodium chloride cotransporter) axis in the kidneys of the Mg2+-deficient DBA (DBA/2J) and catechol-O-methyl transferase inhibitor (COMTi)–treated BL6 (C57BL/6J) mice and 2-methoxyestradiol (2-ME) ameliorated. Representative Western blotting images of (A) Mg2+-deficient male DBA mice and (B) male BL6 mice treated with COMTi. Actin was used as a loading control. Densitometric data analysis of ATR1, t-SPAK (total NCC)/p-SPAK (phosphorylated SPAK), and t-NCC (total NCC)/p-NCC (phosphorylated NCC) was shown on the right. ATR1 was normalized to actin, and p-SPAK and p-NCC were normalized to t-SPAK and t-NCC, respectively. N=5 in each group. Schemes of the animal protocol with hydrochlorothiazide (HCTZ) treatment, weekly systolic BP and systolic BP at wk 5 of (C) Mg2+-deficient male DBA mice and (D) male BL6 mice treated with COMTi. These experiments followed the same protocols as 2-ME experiments. HCTZ was injected intraperitoneally from wk 3. N=7 in all groups. The graph shows the mean±SEM. The significance was determined by 1-way ANOVA for Western blot analysis and 2-way ANOVA for BP and is represented as 1-way ANOVA. BP indicates blood pressure; HS, high salt or 8% NaCl.
To further confirm the activation of the NCC axis in our model, we administered hydrochlorothiazide, an inhibitor of NCC, to the Mg2+-deficient DBA mice and COMTi-treated BL6 mice under high-salt conditions (Figure 3C and 3D). A significant decline in sBP was observed in the hydrochlorothiazide-treated groups to the same extent as 2-ME treatment in both strains (Figure 3C and 3D).

Female Ovariectomized DBA Mice Developed SSH Under Mg2+-Deficient and High-Salt Condition

Female DBA mice with or without ovariectomy were fed Mg2+-deficient or high-salt diet (Figure 4A). There was no difference in body weight or basal plasma Mg2+ between the sham and ovariectomized mice (Figure 4B and 4C). Although the sham mice maintained the normal sBP regardless of the Mg2+ or salt concentration, the ovariectomized mice developed SSH only in the Mg2+-deficient and high-salt conditions, and 2-ME normalized the sBP of these mice (Figure 4D). The fluid and Na+ balances of female DBA mice were in the same trend as these of male DBA mice (Figure S7).
Figure 4. Mg2+-deficient ovariectomized (OVX) DBA (DBA/2J) mice developed salt-sensitive hypertension under high-salt (HS) conditions and 2-methoxyestradiol (2-ME) normalized systolic BP. A, Scheme of the Mg2+-deficient HS protocol for the sham or OVX DBA mice. Half of the mice fed 0.1% Mg2+/0.03% Mg2++0.6% NaCl diet was replaced with a 0.1% Mg2+/0.03% Mg2++8% NaCl diet at wk 2, and 2-ME was injected intraperitoneally from wk 3. B, Body weight (BW) at wk 5.C, Plasma Mg2+ concentration at wk 5. D, Weekly systolic BP and systolic BP at wk 5. For every figure, N=3 in the OVX 0.1% Mg2+ and OVX 0.03% Mg2+ groups, and N=6 in the other groups. The graph is expressed as the mean±SEM. BP indicates blood pressure. The significance was determined by three-way ANOVA for comparisons within one strain or by t test for comparison between 2 strains and is represented as *P<0.05 or ** P<0.01.
Ovariectomy alone did not alter the COMT activity in normal Mg2+ condition; however, Mg2+ deficiency significantly decreased the COMT activity of ovariectomized mice regardless of salt concentration as compared with normal Mg2+ ovariectomized mice. 2-ME treatment did not restore the activity (Figure S8).

Kidney ATR1-SPAK-NCC Axis Was Activated in High-Salt–Loaded Mg2+-Deficient Ovariectomized Mice

Western blot analysis of female DBA kidney protein extractions revealed that activation of ATR1-SPAK-NCC axis was upregulated in high-salt–loaded Mg2+-deficient ovariectomized mice compared with the other groups and was suppressed by 2-ME (Figure 5).
Figure 5. High salt (HS) activated the ATR1 (angiotensin II type 1 receptor)-SPAK (serine-proline alanine-rich kinase)-NCC (sodium chloride cotransporter) axis in the kidneys of the Mg2+-deficient ovariectomized (OVX) DBA (DBA/2J) and 2-methoxyestradiol (2-ME) ameliorated. Representative Western blotting images of female DBA mice. Actin was used as a loading control. Densitometric data analysis of ATR1, t-SPAK (total NCC)/p-SPAK (phosphorylated SPAK), and t-NCC (total NCC)/p-NCC (phosphorylated NCC) on the right. ATR1 was normalized to actin, and p-SPAK and p-NCC were normalized to t-SPAK and t-NCC, respectively. N=3 in OVX 0.1% Mg2+ and OVX 0.03% Mg2+, and N=5 in the other groups. The graph shows the mean±SEM. The significance was determined by 1-way ANOVA and is represented as *P<0.05 or **P<0.01.

Strain and Genetic Difference of Kidney Injury in the Response to Mg2+ Deficiency, High-Salt Load, and the Interventions

In the male DBA mice, urine albumin to creatinine ratio was increased significantly by high-salt load but was decreased neither by 2-ME nor hydrochlorothiazide (Figure 6A). In the COMTi BL6 male mice, not high salt alone but COMT inhibition along with high-salt load was required to increased urine albumin to creatinine ratio, which was significantly decreased either by 2-ME or hydrochlorothiazide (Figure 6B). In the female DBA mice, only the high-salt–loaded Mg2+-deficient ovariectomized mice showed elevated urine albumin to creatinine ratio, which was ameliorated by 2-ME (Figure 6C).
Figure 6. Urine albumin to creatinine ratio. Twenty-four–hour urine was used for the albuminuria assay and creatinine measurement. A, Mg2+-deficient male DBA (DBA/2J) mice. N=4 in the 0.03% Mg2+ and 0.03% Mg2+ high-salt (HS) 2-methoxyestradiol (2-ME) group, N=7 in the 0.03% Mg2+ HS hydrochlorothiazide (HCTZ) group, and N=5 in the other groups. B, Catechol-O-methyl transferase inhibitor (COMTi)–treated male BL6 (C57BL/6J) mice. N=4 in HS group, and N=5 in other groups. C, Mg2+-deficient female DBA mice. N=3 in the 0.1% Mg2+ ovariectomized (OVX) DBA and 0.03% Mg2+ OVX DBA groups and N=5 in the other groups. The graph shows the mean±SEM. The significance was determined by t test and is represented as *P<0.05 or **P<0.01. Alb/cre indicates albumin to creatinine ratio.
E2 levels in male mice were higher in DBA mice than BL6 mice; Mg2+ concentration or 2-ME treatment did not affect the E2 levels within each strain (Figure S9A). In female DBA mice, E2 levels were higher trend in sham mice than ovariectomized mice. Female E2 levels were affected neither by concentration of salt/Mg2+ nor 2-ME treatment (Figure S9B).

Discussion

Elevated salt sensitivity is one of the major causes of hypertension36 and is also associated with chronic kidney disease, another disease linked with a COMT-deficient genetic background.37 From previous reports regarding the role of COMT deficiency in the pathogenesis of preeclampsia13 and the link between preeclampsia and SSH,14 we hypothesize that COMT deficiency could be a shared molecular mechanism in the onset of preeclampsia and SSH. Therefore, this study focused on the effect of COMT deficiency on SSH and identified an interactive effect of dietary Mg2+ insufficiency and genetic COMT deficiency that induced SSH. In brief, our novel findings were as follows: (1) COMT activity was directly proportional to Mg2+ concentration in vitro, (2) Mg2+ deficiency induced SSH in the genetically low COMT strain DBA under high-salt conditions, and 2-ME, a metabolite of COMT, attenuated the COMT deficiency–induced SSH, (3) COMTi-treated BL6, a genetically high COMT strain, expressed similar phenotypes as Mg2+-deficient DBA, (4) upregulation of the ATR1-SPAK-NCC axis was involved in COMT deficiency–induced SSH, and (5) ovariectomy-induced SSH was observed in DBA mice under low Mg2+ and high-salt condition and was ameliorated by 2-ME. ATR1-SPAK-NCC pathway was also upregulated in the kidney of SSH-developed ovariectomized DBA mice.
The recommended daily allowance of Mg2+ is ≈300 to 400 mg; studies from several countries revealed that between 20% and 80% of the population, depending on gender and age, do not meet their daily requirement of Mg2+ intake.38 In general, women have a higher risk of inadequate Mg2+ intake than men, especially pregnant women and aged women, because serum Mg2+ gradually decreases during pregnancy due to the significant increase in demand for Mg2+ and aging reduces intestinal permeability to Mg2+.38,39 Higher prevalence of Mg2+ deficiency might promote development of preeclampsia in pregnant women and increased risk of SSH in postmenopausal women compared to men at the same age.15,40
In terms of the effect of Mg2+ deficiency on COMT activity and the development of SSH, only DBA, a strain with genetically low COMT activity, was strongly affected by Mg2+ deficiency. Interestingly, only in DBA, urinary Mg2+ excretion was significantly increased by high-salt load along with the increase in urinary Ca2+ excretion (Figure S2D). This phenomenon was also reported in high-salt–loaded Dahl salt–sensitive rats and Sprague-Dawley rat.41–43 Although there was no change in plasma Mg2+, the high-salt–induced upregulation of urinary Mg2+ excretion might lower the intracellular Mg2+ concentration in DBA, which could further reduce the activity of COMT. Indeed, our suggestion is reinforced by the report by Resnick et al44 describing that although no significant difference was found in plasma Mg2+ between salt-sensitive and insensitive patients under high-salt conditions, cytosolic free Mg2+ was significantly decreased only in salt-sensitive patients. Moreover, our results correlate with a previous report of COMT activity suppressed by high-salt load in Dahl salt–sensitive rats, whose COMT expression is known to be lower than that in other rats.19,45
Mechanism of SSH is widely studied such that salt increases vascular reactivity, endothelial damages, production of reactive oxygen species,46–48 and sympathetic nerve activity.49 COMT deficiency along with other triggers such as AII is also known to increase these events.19,23,50 In this study, we have shown that COMT deficiency induced either by Mg2+ deficiency or COMT inhibitor developed hypertension not by itself but by coadministration with high salt via upregulation of NCC. The mechanism of how NCC induces hypertension is still under investigation; however, antihypertensive effect of hydrochlorothiazide in our study indicated that reduced salt reabsorption itself via NCC but not the other sodium channels or transporters is enough to lower BP under high-salt and COMT-deficient condition. The antihypertensive effect of 2-ME might have 2 roles, first via reducing salt reabsorption in the same manner as hydrochlorothiazide, and second via compensating COMT deficiency which could also restore vascular homeostasis. As our result and previous report19 suggested, high salt itself reduces COMT activity, creating a vicious cycle and possibly worsening the hypertension and related syndromes, such as kidney injury. Further study is required for the whole-body effects of 2-ME under high-salt conditions.
In contrast to our study, Ferdaus et al51 reported that Mg2+ deficiency downregulates total NCC abundance by NEDD4-2 (neuronal precursor cell developmentally downregulated 4-2)–mediated ubiquitin-dependent degradation of NCC. Their study emphasized that Mg2+ deficiency counteracts the upregulation of WNK-SPAK-NCC axis induced by hypokalemia in the normal salt diet–fed mice. It is unclear how NEDD4-2 affects the NCC regulation under the high-salt condition. Also, the involvement of NEDD4-2 in Mg2+ dependent COMT activity, and subsequent regulation of NCC levels is not elucidated yet. These data including ours suggest the essential role of Mg2+ in renal Na+ homeostasis by fine-tuning.
Regarding the effect of 2-ME on NCC, our results indicated that under high-salt conditions, 2-ME insufficiency due to COMT deficiency led to the upregulation of ATR1, which then activates SPAK-NCC. Previous reports have revealed the link between 2-ME and AII sensitivity in several organs. In the aorta, our group has reported that 2-ME insufficiency increased BP and kidney injury by upregulating the expression of ATR1 in the aorta with low dose AII,23 and in the brain, Singh et al52 recently reported that 2-ME attenuated AII-induced upregulation of sympathetic activities and thus revealed a protective effect against hypertension. 2-ME would be essential for the BP homeostasis via modulation of AII sensitivity in multiple organs.
SSH is an estrogen-related hypertension whose risk increases after menopause for many women.15,53 Although endogenous estrogen protects against increasing salt sensitivity, several studies suggest that oral hormone replacement therapy does not affect or can slightly increase BP in postmenopausal women.15,54 Our study identified that the development of SSH is not due to the elevation of E2 but due to a lack of the estrogen metabolite 2-ME; therefore, we propose that 2-ME administration could be a new treatment option for SSH instead of estrogen for postmenopausal women. The higher possibility of developing SSH in women with a history of preeclampsia during the premenopausal period14,53 might be the consequence of a low COMT genetic background. In addition, a study of Dahl salt–sensitive rats revealed that Dahl salt–sensitive rats, but not rats with spontaneous hypertension, developed superimposed preeclampsia during pregnancy.55 Thus, we assume that SSH and preeclampsia may share a similar pathogenesis, which we propose is COMT deficiency or lack of 2-ME. Further study with a pregnant model is required to clearly show this relationship. In addition, among the many factors that could affect COMT activity, Mg2+ is worthy of attention considering its insufficient intake worldwide.
A limitation of this study is that there might be variety of genetic variances between BL6 mice and DBA mice other than COMT. Although our study showed the impact of COMT deficiency on SSH development, the different responses to 2-ME/hydrochlorothiazide on kidney injury might be due to other genetic variances. Lack of 2-ME measurement is another limitation of this study. We tried several methods, but mouse plasma 2-ME was unable to be quantified by a commercial assay system or newly developed mass spectrometer-based method by which human plasma 2-ME level was successfully measured, probably due to the too low levels of mouse plasma 2-ME. However, recovery from SSH by 2-ME treatment indirectly suggests that 2-ME insufficiency is the major cause of the development of SSH under COMT-deficient conditions. The ovariectomized DBA female mice displayed clearer phenotypes than male mice, as shown in kidney injury, indicating a sudden and large drop in 2-ME level strongly affects BP regulation and kidney function. Lastly, the specificity of the ATR1 antibody used in this study (Sigma Aldrich SAB3500209) is a significant concern. Benicky et al56 reported that many of the commercial ATR1 antibodies were nonspecific. The particular antibody we have chosen (SAB3500209) was not listed in Benicky et al’s article. However, although we have confirmed the specificity of SAB3500209 in vitro overexpression/knockdown studies,23 the specificity of SAB3500209 in vivo was still a debatable issue since we could not validate the specificity of SAB3500209 in AT1R knockout mice. Future validation would be required.
Additional discussion is described in the Data Supplement.
In conclusion, we revealed that Mg2+ insufficiency exaggerated low COMT activity and subsequently induced SSH, suggesting a new role of COMT as an ATR1-SPAK-NCC regulator via 2-ME production.

Perspectives

This study focused on genetical variance of COMT activity as well as the impact of Mg2+ deficiency on COMT activity and identified that Mg2+ deficiency induced COMT deficiency/2-ME insufficiency only in genetically low COMT strain. COMT deficiency/2-ME insufficiency developed SSH via upregulating ATR1-SPAK-NCC axis. In female, only ovariectomized mice developed SSH under Mg2+ deficiency suggesting the importance of sufficient amount of 2-ME production. Inadequate intake of Mg2+ is a worldwide topic for decades, especially in elderly women who are at increased risk of SSH. This study revealed the importance of adequate Mg2+ intake for prevention of SSH. 2-ME replacement therapy instead of estrogen replacement therapy might be another option for treatment of SSH.

Acknowledgments

We declare that there are no competing interests associated with this project. K. Kanasaki collaborated with Boehringer Ingelheim at both Kanazawa Medical University and Shimane University with the project not related to this article. Boehringer Ingelheim, Mitsubishi-Tanabe Pharma, and Ono Pharmaceutical contributed to establishing the Division of Anticipatory Molecular Food Science and Technology. K. Kanasaki is under a consultancy agreement with Boehringer Ingelheim.

Novelty and Significance

VIEW EDITORIAL:Mg2+ Channels as the Link Between Mg2+ Deficiency and COMT Downregulation in Salt-Sensitive Hypertension

What Is New?

•
Mg2+ deficiency induces salt-sensitive hypertension (SSH) via lowering COMT (catechol-O-methyl transferase) activity and subsequently reducing 2-methoxyestradiol production in the genetically low COMT mice.
•
2-methoxyestradiol maintains blood pressure homeostasis via regulation of ATR1 (angiotensin II type 1 receptor)-SPAK (serine-proline alanine-rich kinase)-NCC (sodium chloride cotransporter) axis.

What Is Relevant?

•
Elevated salt sensitivity is a major cause of hypertension; however, only few treatment options, such as salt restriction, are available. Our findings that the interaction between genetically low COMT activity and Mg2+ deficiency could cause SSH suggest the importance of adequate intake of Mg2+ and 2-methoxyestradiol sufficiency for prevention of SSH.

Summary

Genetic strength of COMT activity affects the incidence of SSH. For low COMT activity individuals, adequate Mg2+ intake and 2-methoxyestradiol replacement prevent development of SSH.

Footnote

Nonstandard Abbreviation and Acronyms

2-ME
2-methoxyestradiol
AII
angiotensin II
ATR1
angiotensin II type 1 receptor
BL6
C57BL/6J
BP
Blood pressure
COMT
catechol-O-methyl transferase
COMTi
COMT inhibitor
DBA
DBA/2J
E2
17-β estradiol
NCC
sodium chloride cotransporter
p-NCC
phosphorylated NCC
SPAK
serine-proline alanine-rich kinase
SSH
salt-sensitive hypertension

Supplemental Material

File (hyp_hype-2020-16377_supp2.pdf)
File (hyp_hype-2020-16377_supp3.pdf)
File (hyp_hype-2020-16377_supp4.pdf)

References

1.
Dubey RK. 2-Methoxyestradiol: a 17β-estradiol metabolite with gender-independent therapeutic potential. Hypertension. 2017;69:1014–1016. doi: 10.1161/HYPERTENSIONAHA.117.09265
Crossref
PubMed
Google Scholar
2.
Kanasaki M, Srivastava SP, Yang F, Xu L, Kudoh S, Kitada M, Ueki N, Kim H, Li J, Takeda S, et al. Deficiency in catechol-o-methyltransferase is linked to a disruption of glucose homeostasis in mice. Sci Rep. 2017;7:7927. doi: 10.1038/s41598-017-08513-w
Crossref
PubMed
Google Scholar
3.
Chen J, Lipska BK, Halim N, Ma QD, Matsumoto M, Melhem S, Kolachana BS, Hyde TM, Herman MM, Apud J, et al. Functional analysis of genetic variation in catechol-O-methyltransferase (COMT): effects on mRNA, protein, and enzyme activity in postmortem human brain. Am J Hum Genet. 2004;75:807–821. doi: 10.1086/425589
Crossref
PubMed
Google Scholar
4.
Htun NC, Miyaki K, Song Y, Ikeda S, Shimbo T, Muramatsu M. Association of the catechol-O-methyl transferase gene Val158Met polymorphism with blood pressure and prevalence of hypertension: interaction with dietary energy intake. Am J Hypertens. 2011;24:1022–1026. doi: 10.1038/ajh.2011.93
Crossref
PubMed
Google Scholar
5.
Voutilainen S, Tuomainen TP, Korhonen M, Mursu J, Virtanen JK, Happonen P, Alfthan G, Erlund I, North KE, Mosher MJ, et al. Functional COMT Val158Met polymorphism, risk of acute coronary events and serum homocysteine: the Kuopio ischaemic heart disease risk factor study. PLoS One. 2007;2:e181. doi: 10.1371/journal.pone.0000181
Crossref
PubMed
Google Scholar
6.
Roten LT, Fenstad MH, Forsmo S, Johnson MP, Moses EK, Austgulen R, Skorpen F. A low COMT activity haplotype is associated with recurrent preeclampsia in a Norwegian population cohort (HUNT2). Mol Hum Reprod. 2011;17:439–446. doi: 10.1093/molehr/gar014
Crossref
PubMed
Google Scholar
7.
Tsao D, Diatchenko L, Dokholyan NV. Structural mechanism of S-adenosyl methionine binding to catechol O-methyltransferase. PLoS One. 2011;6:e24287. doi: 10.1371/journal.pone.0024287
Crossref
PubMed
Google Scholar
8.
Jahnen-Dechent W, Ketteler M. Magnesium basics. Clin Kidney J. 2012;5:i3–i14.
Crossref
PubMed
Google Scholar
9.
Ismail AAA, Ismail Y, Ismail AA. Chronic magnesium deficiency and human disease; time for reappraisal? QJM. 2018;111:759–763. doi: 10.1093/qjmed/hcx186
Crossref
PubMed
Google Scholar
10.
Duley L, Meher S, Abalos E. Management of pre-eclampsia. BMJ. 2006;332:463–468. doi: 10.1136/bmj.332.7539.463
Crossref
PubMed
Google Scholar
11.
Holcberg G, Sapir O, Hallak M, Alaa A, Shorok HY, David Y, Katz M, Huleihel M. Selective vasodilator effect of magnesium sulfate in human placenta. Am J Reprod Immunol. 2004;51:192–197. doi: 10.1111/j.1600-0897.2004.00115.x
Crossref
PubMed
Google Scholar
12.
Kawasaki K, Kondoh E, Chigusa Y, Kawamura Y, Mogami H, Takeda S, Horie A, Baba T, Matsumura N, Mandai M, et al. Metabolomic profiles of placenta in preeclampsia. Hypertension. 2019;73:671–679. doi: 10.1161/HYPERTENSIONAHA.118.12389
Crossref
PubMed
Google Scholar
13.
Kanasaki K, Palmsten K, Sugimoto H, Ahmad S, Hamano Y, Xie L, Parry S, Augustin HG, Gattone VH, Folkman J, et al. Deficiency in catechol-O-methyltransferase and 2-methoxyoestradiol is associated with pre-eclampsia. Nature. 2008;453:1117–1121. doi: 10.1038/nature06951
Crossref
PubMed
Google Scholar
14.
Martillotti G, Ditisheim A, Burnier M, Wagner G, Boulvain M, Irion O, Pechère-Bertschi A. Increased salt sensitivity of ambulatory blood pressure in women with a history of severe preeclampsia. Hypertension. 2013;62:802–808. doi: 10.1161/HYPERTENSIONAHA.113.01916
Crossref
PubMed
Google Scholar
15.
Kim JM, Kim TH, Lee HH, Lee SH, Wang T. Postmenopausal hypertension and sodium sensitivity. J Menopausal Med. 2014;20:1–6. doi: 10.6118/jmm.2014.20.1.1
Crossref
PubMed
Google Scholar
16.
Schulman IH, Aranda P, Raij L, Veronesi M, Aranda FJ, Martin R. Surgical menopause increases salt sensitivity of blood pressure. Hypertension. 2006;47:1168–1174. doi: 10.1161/01.HYP.0000218857.67880.75
Crossref
PubMed
Google Scholar
17.
Brinson KN, Rafikova O, Sullivan JC. Female sex hormones protect against salt-sensitive hypertension but not essential hypertension. Am J Physiol Regul Integr Comp Physiol. 2014;307:R149–R157. doi: 10.1152/ajpregu.00061.2014
Crossref
PubMed
Google Scholar
18.
Izumiyama K, Osanai T, Sagara S, Yamamoto Y, Itoh T, Sukekawa T, Nishizaki F, Magota K, Okumura K. Estrogen attenuates coupling factor 6-induced salt-sensitive hypertension and cardiac systolic dysfunction in mice. Hypertens Res. 2012;35:539–546. doi: 10.1038/hr.2011.232
Crossref
PubMed
Google Scholar
19.
Hirano Y, Tsunoda M, Shimosawa T, Matsui H, Fujita T, Funatsu T. Suppression of catechol-O-methyltransferase activity through blunting of alpha2-adrenoceptor can explain hypertension in Dahl salt-sensitive rats. Hypertens Res. 2007;30:269–278. doi: 10.1291/hypres.30.269
Crossref
PubMed
Google Scholar
20.
Frame AA, Puleo F, Kim K, Walsh KR, Faudoa E, Hoover RS, Wainford RD. Sympathetic regulation of NCC in norepinephrine-evoked salt-sensitive hypertension in Sprague-Dawley rats. Am J Physiol Renal Physiol. 2019;317:F1623–F1636. doi: 10.1152/ajprenal.00264.2019
Crossref
PubMed
Google Scholar
21.
Ostrosky-Frid M, Castañeda-Bueno M, Gamba G. Regulation of the renal NaCl cotransporter by the WNK/SPAK pathway: lessons learned from genetically altered animals. Am J Physiol Renal Physiol. 2019;316:F146–F158. doi: 10.1152/ajprenal.00288.2018
Crossref
PubMed
Google Scholar
22.
Murthy M, Kurz T, O’Shaughnessy KM. WNK signalling pathways in blood pressure regulation. Cell Mol Life Sci. 2017;74:1261–1280. doi: 10.1007/s00018-016-2402-z
Crossref
PubMed
Google Scholar
23.
Ueki N, Kanasaki K, Kanasaki M, Takeda S, Koya D. Catechol-O-methyltransferase deficiency leads to hypersensitivity of the pressor response against angiotensin II. Hypertension. 2017;69:1156–1164. doi: 10.1161/HYPERTENSIONAHA.117.09247
Crossref
PubMed
Google Scholar
24.
Jeffery DR, Roth JA. Kinetic reaction mechanism for magnesium binding to membrane-bound and soluble catechol O-methyltransferase. Biochemistry. 1987;26:2955–2958. doi: 10.1021/bi00384a042
Crossref
PubMed
Google Scholar
25.
Bidart JM, Assicot M, Bohuon C. Catechol-O-methyl transferase activity in human mononuclear cells. Res Commun Chem Pathol Pharmacol. 1981;34:47–54.
PubMed
Google Scholar
26.
Piedrafita FJ, Elorriaga C, Fernández-Alvarez E, Nieto O. Inhibition of catechol-O-methyltransferase by N-(3,4-dihydroxyphenyl) maleimide. J Enzyme Inhib. 1990;4:43–50. doi: 10.3109/14756369009030387
Crossref
PubMed
Google Scholar
27.
Iijima H, Takebe K, Suzuki M, Kobayashi H, Takamiya T, Saito H, Niwa N, Kuwada-Kusunose T. Crystal structure of catechol O-methyltransferase complexed with nitecapone. Chem Pharm Bull (Tokyo). 2020;68:447–451. doi: 10.1248/cpb.c20-00011
Crossref
PubMed
Google Scholar
28.
Takezawa K, Tsunoda M, Watanabe N, Imai K. An automatic analyzer for catecholamines and their 3-O-methyl metabolites using a micro coulometric flow cell as a postcolumn reactor for fluorogenic reaction. Anal Chem. 2000;72:4009–4014. doi: 10.1021/ac0003697
Crossref
PubMed
Google Scholar
29.
Tsunoda M, Takezawa K, Santa T, Imai K. Simultaneous automatic determination of catecholamines and their 3-O-methyl metabolites in rat plasma by high-performance liquid chromatography using peroxyoxalate chemiluminescence reaction. Anal Biochem. 1999;269:386–392. doi: 10.1006/abio.1999.4043
Crossref
PubMed
Google Scholar
30.
Iijima H, Okada Y, Tsunoda M, Takamiya T, Imai K. Quantification of norepinephrine and its metabolites in the plasma of renal failure models. Nephron Physiol. 2010;116:p9–p16. doi: 10.1159/000318177
Crossref
PubMed
Google Scholar
31.
She QB, Nagao I, Hayakawa T, Tsuge H. A simple HPLC method for the determination of S-adenosylmethionine and S-adenosylhomocysteine in rat tissues: the effect of vitamin B6 deficiency on these concentrations in rat liver. Biochem Biophys Res Commun. 1994;205:1748–1754. doi: 10.1006/bbrc.1994.2871
Crossref
PubMed
Google Scholar
32.
Parks C, Giorgianni F, Jones BC, Beranova-Giorgianni S, Moore Ii BM, Mulligan MK. Comparison and functional genetic analysis of striatal protein expression among diverse inbred mouse strains. Front Mol Neurosci. 2019;12:128. doi: 10.3389/fnmol.2019.00128
Crossref
PubMed
Google Scholar
33.
Grice DE, Reenilä I, Männistö PT, Brooks AI, Smith GG, Golden GT, Buxbaum JD, Berrettini WH. Transcriptional profiling of C57 and DBA strains of mice in the absence and presence of morphine. BMC Genomics. 2007;8:76. doi: 10.1186/1471-2164-8-76
Crossref
PubMed
Google Scholar
34.
de Jong JC, Willems PH, Mooren FJ, van den Heuvel LP, Knoers NV, Bindels RJ. The structural unit of the thiazide-sensitive NaCl cotransporter is a homodimer. J Biol Chem. 2003;278:24302–24307. doi: 10.1074/jbc.M303101200
Crossref
PubMed
Google Scholar
35.
McKee JA, Kumar S, Ecelbarger CA, Fernández-Llama P, Terris J, Knepper MA. Detection of Na(+) transporter proteins in urine. J Am Soc Nephrol. 2000;11:2128–2132.
Crossref
PubMed
Google Scholar
36.
Weinberger MH. Salt sensitivity of blood pressure in humans. Hypertension. 1996;27(3 pt 2):481–490. doi: 10.1161/01.hyp.27.3.481
Crossref
PubMed
Google Scholar
37.
Yoshida T, Kato K, Yokoi K, Oguri M, Watanabe S, Metoki N, Yoshida H, Satoh K, Aoyagi Y, Nishigaki Y, et al. Association of genetic variants with chronic kidney disease in individuals with different lipid profiles. Int J Mol Med. 2009;24:233–246. doi: 10.3892/ijmm_00000226
Crossref
PubMed
Google Scholar
38.
DiNicolantonio JJ, O’Keefe JH, Wilson W. Subclinical magnesium deficiency: a principal driver of cardiovascular disease and a public health crisis. Open Heart. 2018;5:e000668. doi: 10.1136/openhrt-2017-000668
Crossref
PubMed
Google Scholar
39.
Fine KD, Santa Ana CA, Porter JL, Fordtran JS. Intestinal absorption of magnesium from food and supplements. J Clin Invest. 1991;88:396–402. doi: 10.1172/JCI115317
Crossref
PubMed
Google Scholar
40.
Faulkner JL, Belin de Chantemèle EJ. Female sex, a major risk factor for salt-sensitive hypertension. Curr Hypertens Rep. 2020;22:99. doi: 10.1007/s11906-020-01113-6
Crossref
PubMed
Google Scholar
41.
Ikari A, Kano T, Suketa Y. Magnesium influx enhanced by nitric oxide in hypertensive rat proximal tubule cells. Biochem Biophys Res Commun. 2002;294:710–713. doi: 10.1016/S0006-291X(02)00542-9
Crossref
PubMed
Google Scholar
42.
Lee CT, Lien YH, Lai LW, Ng HY, Chiou TT, Chen HC. Variations of dietary salt and fluid modulate calcium and magnesium transport in the renal distal tubule. Nephron Physiol. 2012;122:19–27. doi: 10.1159/000353199
Crossref
PubMed
Google Scholar
43.
Gu JW, Bailey AP, Tan W, Shparago M, Young E. Long-term high salt diet causes hypertension and decreases renal expression of vascular endothelial growth factor in Sprague-Dawley Rats. J Am Soc Hypertens. 2008;2:275–285. doi: 10.1016/j.jash.2008.03.001
Crossref
PubMed
Google Scholar
44.
Resnick LM, Gupta RK, DiFabio B, Barbagallo M, Mann S, Marion R, Laragh JH. Intracellular ionic consequences of dietary salt loading in essential hypertension. Relation to blood pressure and effects of calcium channel blockade. J Clin Invest. 1994;94:1269–1276. doi: 10.1172/JCI117445
Crossref
PubMed
Google Scholar
45.
Kajimoto K, Hiura Y, Sumiya T, Yasui N, Okuda T, Iwai N. Exclusion of the catechol-o-methyltransferase gene from genes contributing to salt-sensitive hypertension in Dahl salt-sensitive rats. Hypertens Res. 2007;30:459–467. doi: 10.1291/hypres.30.459
Crossref
PubMed
Google Scholar
46.
Barron LA, Giardina JB, Granger JP, Khalil RA. High-salt diet enhances vascular reactivity in pregnant rats with normal and reduced uterine perfusion pressure. Hypertension. 2001;38(3 pt 2):730–735. doi: 10.1161/01.hyp.38.3.730
Crossref
PubMed
Google Scholar
47.
Nurkiewicz TR, Boegehold MA. High salt intake reduces endothelium-dependent dilation of mouse arterioles via superoxide anion generated from nitric oxide synthase. Am J Physiol Regul Integr Comp Physiol. 2007;292:R1550–R1556. doi: 10.1152/ajpregu.00703.2006
Crossref
PubMed
Google Scholar
48.
Li L, Lai EY, Luo Z, Solis G, Mendonca M, Griendling KK, Wellstein A, Welch WJ, Wilcox CS. High salt enhances reactive oxygen species and angiotensin II contractions of glomerular afferent arterioles from mice with reduced renal mass. Hypertension. 2018;72:1208–1216. doi: 10.1161/HYPERTENSIONAHA.118.11354
Crossref
PubMed
Google Scholar
49.
Guild SJ, McBryde FD, Malpas SC, Barrett CJ. High dietary salt and angiotensin II chronically increase renal sympathetic nerve activity: a direct telemetric study. Hypertension. 2012;59:614–620. doi: 10.1161/HYPERTENSIONAHA.111.180885
Crossref
PubMed
Google Scholar
50.
Liao S, Wu H, Chen R. Apolipoprotein A1 mimetic peptide ATI-5261 reverses arterial stiffness at late pregnancy and early postpartum in a COMT-/- mouse model of preeclampsia. Clin Hypertens. 2018;24:11. doi: 10.1186/s40885-018-0097-1
Crossref
PubMed
Google Scholar
51.
Ferdaus MZ, Mukherjee A, Nelson JW, Blatt PJ, Miller LN, Terker AS, Staub O, Lin DH, McCormick JA. Mg2+ restriction downregulates NCC through NEDD4-2 and prevents its activation by hypokalemia. Am J Physiol Renal Physiol. 2019;317:F825–F838. doi: 10.1152/ajprenal.00216.2019
Crossref
PubMed
Google Scholar
52.
Singh P, Song CY, Dutta SR, Gonzalez FJ, Malik KU. Central CYP1B1 (Cytochrome P450 1B1)-estradiol metabolite 2-methoxyestradiol protects from hypertension and neuroinflammation in female mice. Hypertension. 2020;75:1054–1062. doi: 10.1161/HYPERTENSIONAHA.119.14548
Crossref
PubMed
Google Scholar
53.
Pechère-Bertschi A, Burnier M. Female sex hormones, salt, and blood pressure regulation. Am J Hypertens. 2004;17:994–1001. doi: 10.1016/j.amjhyper.2004.08.009
Crossref
PubMed
Google Scholar
54.
Chiu CL, Lujic S, Thornton C, O’Loughlin A, Makris A, Hennessy A, Lind JM. Menopausal hormone therapy is associated with having high blood pressure in postmenopausal women: observational cohort study. PLoS One. 2012;7:e40260. doi: 10.1371/journal.pone.0040260
Crossref
PubMed
Google Scholar
55.
Gillis EE, Williams JM, Garrett MR, Mooney JN, Sasser JM. The Dahl salt-sensitive rat is a spontaneous model of superimposed preeclampsia. Am J Physiol Regul Integr Comp Physiol. 2015;309:R62–R70. doi: 10.1152/ajpregu.00377.2014
Crossref
PubMed
Google Scholar
56.
Benicky J, Hafko R, Sanchez-Lemus E, Aguilera G, Saavedra JM. Six commercially available angiotensin II AT1 receptor antibodies are non-specific. Cell Mol Neurobiol. 2012;32:1353–1365. doi: 10.1007/s10571-012-9862-y
Crossref
PubMed
Google Scholar

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Volume 78 • Number 1 • July 2021
Pages: 138 - 150
PubMed: 33840199

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Received: 25 September 2020
Accepted: 10 March 2021
Published online: 12 April 2021
Published in print: July 2021

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Keywords

  1. 2-methoxyestradiol
  2. blood pressure
  3. magnesium
  4. mice
  5. sodium chloride

Subjects

  1. Hypertension
  2. Preeclampsia

Authors

Affiliations

Asako Kumagai
Faculty of Medicine, Internal Medicine I, Shimane University, Izumo, Japan (A.K., K.K.).
Department of Obstetrics and Gynecology, Graduate School of Medicine, Juntendo University, Bunkyo, Tokyo, Japan (A.K., S.T., A.I.).
Department of Diabetology and Endocrinology (A.K., D.K.), Kanazawa Medical University, Ishikawa, Japan.
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Satoru Takeda
Department of Obstetrics and Gynecology, Graduate School of Medicine, Juntendo University, Bunkyo, Tokyo, Japan (A.K., S.T., A.I.).
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Eisei Sohara
Department of Nephrology, Tokyo Medical and Dental University, Yushima, Bunkyo, Japan (E.S., S.U.).
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Shinichi Uchida
Department of Nephrology, Tokyo Medical and Dental University, Yushima, Bunkyo, Japan (E.S., S.U.).
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Hiroshi Iijima https://orcid.org/0000-0001-8402-0292
School of Pharmacy, Nihon University, Chiba, Japan (H.I.).
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Astuo Itakura https://orcid.org/0000-0002-4554-164X
Department of Obstetrics and Gynecology, Graduate School of Medicine, Juntendo University, Bunkyo, Tokyo, Japan (A.K., S.T., A.I.).
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Daisuke Koya
Department of Diabetology and Endocrinology (A.K., D.K.), Kanazawa Medical University, Ishikawa, Japan.
Division of Anticipatory Molecular Food Science and Technology, Medical Research Institute (D.K., K.K.), Kanazawa Medical University, Ishikawa, Japan.
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Keizo Kanasaki https://orcid.org/0000-0002-9563-502X [email protected]
Faculty of Medicine, Internal Medicine I, Shimane University, Izumo, Japan (A.K., K.K.).
Division of Anticipatory Molecular Food Science and Technology, Medical Research Institute (D.K., K.K.), Kanazawa Medical University, Ishikawa, Japan.
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Notes

The Data Supplement is available with this article at Supplemental Material.
For Sources of Funding and Disclosures, see page 149.
Correspondence to: Keizo Kanasaki, Department of Internal Medicine 1, Faculty of Medicine, Shimane University, 89-1 Enya-cho, Izumo 693-8501, Japan. Email [email protected]

Disclosures

Disclosures None.

Sources of Funding

This study was primarily supported by a grant from the Japan Society for the Promotion of Science to K. Kanasaki (26460403 and 19K08738) and the Uehara Memorial Foundation to K. Kanasaki (2019).

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Dietary Magnesium Insufficiency Induces Salt-Sensitive Hypertension in Mice Associated With Reduced Kidney Catechol-O-Methyl Transferase Activity
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