Sex and Age Result in Differential Regulation of the Renal Thiazide-Sensitive NaCl Cotransporter and the Epithelial Sodium Channel in Angiotensin II-Infused Mice

Background Diabetic nephropathy is a common diabetes mellitus complication associated with hypertension, proteinuria, and excretion of urinary plasmin that activates the epithelial sodium channel, ENaC, in vitro . Here we hypothesized that the deletion of plasminogen and amiloride treatment protect against hypertension in diabetes mellitus. Methods and Results Male plasminogen knockout (plasminogen‐deficient [Plg −/− ]) and wild‐type mice were rendered diabetic with streptozotocin. Arterial blood pressure was recorded continuously by indwelling catheters before and during 10 days of angiotensin II infusion (ANGII; 30–60 ng/kg per minute). The effect of amiloride infusion (2 mg/kg per day, 4 days) was tested in wild‐type, diabetic ANGII‐treated mice. Streptozotocin increased plasma and urine glucose concentrations and 24‐hour urine albumin and plasminogen excretion. Diabetic Plg −/− mice displayed larger baseline albuminuria and absence of urine plasminogen. Baseline mean arterial blood pressure did not differ between groups. Although ANGII elevated blood pressure in wild‐type, diabetic wild‐type, and Plg −/− control mice, ANGII did not change blood pressure in diabetic Plg −/− mice. Compared with ANGII infusion alone, wild‐type ANGII‐infused diabetic mice showed blood pressure reduction upon amiloride treatment. There was no difference in plasma renin, ANGII, aldosterone, tissue prorenin receptor, renal inflammation, and fibrosis between groups. Urine from wild‐type mice evoked larger amiloride‐sensitive current than urine from Plg −/− mice with or without diabetes mellitus. Full‐length γ‐ENaC and α‐ENaC subunit abundances were not changed in kidney homogenates, but the 70 kDa γ‐ENaC cleavage product was increased in diabetic versus nondiabetic mice. Conclusions Plasmin promotes hypertension in diabetes mellitus with albuminuria likely through the epithelial sodium channel.

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Mutagenesis of the Cleavage Site of Pro Renin Receptor Abrogates Angiotensin II-Induced Hypertension in Mice

Hypertension ◽

10.1161/hypertensionaha.121.16770 ◽

2021 ◽

Author(s):

Fei Wang ◽

Yanting Chen ◽

Chang-Jiang Zou ◽

Renfei Luo ◽

Tianxin Yang

Keyword(s):

Angiotensin Ii ◽

Sodium Channel ◽

Cleavage Site ◽

Collecting Duct ◽

Ussing Chamber ◽

Renin Angiotensin System ◽

Epithelial Sodium Channel ◽

Wild Type ◽

Developmental Abnormalities ◽

Induced Hypertension

It is well demonstrated that activation of renal PRR ([pro]renin receptor) contributes to AngII (angiotensin II)-induced hypertension. Relatively, less is known for the function of sPRR (soluble PRR), the extracellular domain of PRR, primarily generated by S1P (site-1 protease) and furin. Moreover, the relationship between PRR/sPRR and the renin-angiotensin system (RAS) has been debated. In the present study, we used CRISPR/Cas9 strategy to generate mice with mutagenesis of the overlapping cleavage site for both proteases in PRR (termed as PRR R279V/L282V ) to examine the phenotype during AngII infusion with particular emphasis on circulating and intrarenal renin status. PRR R279V/L282V mice exhibited a reduction of sPRR level in plasma by ≈53% and in the kidney by ≈82%, were fertile, and had no gross developmental abnormalities. At basal condition, PRR R279V/L282V mice had drastically suppressed renin levels from plasma, urine, and the kidney as compared to wild-type controls. The hypertensive response of PRR R279V/L282V to AngII infusion was blunted in parallel with attenuated response of intrarenal renin and renal medullary α-epithelial sodium channel expression. By using Ussing chamber technique, primary collecting duct cells from PRR R279V/L282V mice exhibited blunted response of epithelial sodium channel activity to AngII as compared to wild-type cells. Together, these results represent strong evidence favoring sPRR as a mediator of AngII-induced hypertension and a master regulator of renin expression. Therefore, PRR should be considered as an integrative member of the RAS.

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