Abstract

Objective: To determine the effects of dietary potassium loading on renal function, blood pressure (BP) and oxidative stress in DOCA-salt rats as a model of mineralocorticoid hypertension.

Design and Methods: After unilateral nephrectomy, male 8-week-old Sprague Dawley rats were divided into 3 groups: a) standard chow (0.66% NaCl, 1.34% KCl), b) NaCl-loaded chow (8% NaCl, 1.34% KCl), or c) NaCl and KCl-loaded chow (8% NaCl, 8% KCl). They were weekly subjected to DOCA treatment (100 mg/kg BW). After 2 weeks, BP, plasma and urinary parameters including biomarkers of oxidative stress (plasma 8-epi-PGF2-alfa and 24-hr urinary 8-OH-dG) were determined. Kidneys were subjected to northern blotting to analyze the expression of LOX-1 (lectin-like oxidized LDL receptor-1) gene.

Results: Treatment with DOCA-salt significantly increased systolic BP, associated with renal hypertrophy, renal dysfunction (the increase of s-Cr, proteinuria), and upregulation of LOX-1 gene. Although potassium overload did not have antihypertensive effect, it ameliorated renal dysfunction, renal LOX-1 gene expression, and the increase of markers of oxidative stress in DOCA-salt rats.

Conclusion: These data support the notion that, in mineralocorticoid hypertension, dietary potassium has a protective effect on the renal function independent of BP.

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