High blood pressure induced by vitamin D deficiency is associated with renal overexpression and hyperphosphorylation of Na+-K+-2Cl-cotransporter type 2

Author(s)

Luchi, Weverton M. ^{[1, 2]} ; Crajoinas, Renato O. ^[1] ; Martins, Flavia L. ^[1] ; Castro, Paulo de C. ^[2] ; Venturini, Gabriela ^[1] ; Seguro, Antonio C. ^[3] ; Girardi, Adriana C. C. ^[1]

Affiliation

^[1] Univ Sao Paulo, Lab Genet & Mol Cardiol, Heart Inst InCor, Med Sch, Ave Dr Eneas de Carvalho Aguiar 44, 10 Andar, BR-05403900 Sao Paulo, SP - Brazil

^[2] Fed Univ Espirito Santo UFES, Dept Internal Med, Vitoria, ES - Brazil

^[3] Univ Sao Paulo, Dept Nephrol LIM 12, Med Sch, Sao Paulo - Brazil

• Document type: Journal article
• Source: Journal of Hypertension; v. 39, n. 5, p. 880-891, MAY 2021.
• Web of Science Citations: 0

Abstract

Objectives: Clinical and epidemiological studies have suggested a correlation between vitamin D deficiency (VDD) and high blood pressure (BP). This study aimed to test the hypothesis that high BP induced by VDD is associated with altered expression and covalent modification of apical sodium transporters along the nephron. The contributions of the intrarenal renin-angiotensin system (RAS) and oxidative stress were also investigated. Methods: Male Wistar rats were fed a vitamin D-free (n = 26) or standard diet (n = 25) for 30 days. BP was recorded using noninvasive and invasive procedures. The expression levels of total and phosphorylated apical sodium transporters in rat renal cortex and medulla were evaluated by immunoblotting. Intrarenal RAS components were assessed by immunoblotting and ELISA. Renal oxidative stress was analyzed by measuring the concentrations of thiobarbituric acid reactive substances and reduced glutathione. Results: Higher BP levels in VDD rats than controls were accompanied by overexpression and hyperphosphorylation of renal cortical and medullary Na+-K+-2Cl- cotransporter type 2, enhanced levels of phosphorylated Na+/H+ exchanger type 3, and reduced expression levels of total and phosphorylated Na+/Cl- cotransporter. Changes in intrarenal RAS induced by VDD vs. controls included the marked elevation of medullary renin expression, higher expression of cortical angiotensinogen, higher urinary angiotensinogen excretion, and higher cortical and medullary angiotensin II content. VDD rats displayed higher thiobarbituric acid reactive substances/glutathione ratios in the renal cortex and medulla than controls. Conclusion: These results suggest that the molecular mechanisms underlying the effects of VDD on BP may include the upregulation of Na+-K+-2Cl- cotransporter type 2 and activation of intrarenal RAS and oxidative stress. (AU)

• FAPESP's process: 16/22140-7 - Molecular bases of renal tubular function and dysfunction
• Grantee: Adriana Castello Costa Girardi
• Support Opportunities: Research Projects - Thematic Grants