Effects of Renin-Angiotensin System Inhibitors on Renal Expression of Renalase in Sprague-Dawley Rats Fed With High Salt Diet.

BACKGROUND/AIMS The aim of our study was to investigate the effect of high-salt diet on the renal expression of renalase and the potential role of the local renin-angiotensin system in this process. METHODS Sprague-Dawley (SD) rats were divided into groups according to salt content in diet and drug treatment as follows: normal-salt diet (NS), high-salt diet (HS), high-salt intake with hydralazine (HS+H), high-salt diet with enalapril (HS+E), and high-salt diet with valsartan (HS+V). The dietary intervention and drugs were given for four weeks. Renin activity and angiotensin II type 1 receptor (AT1R) levels were detected by real-time PCR. Renalase mRNA and protein were also measured. RESULTS After four weeks, systolic blood pressure and proteinuria were significantly increased in the HS group with respect to the NS group. Dietary salt intake caused a dramatic decrease in renalase expression in the rat kidneys. Renal cortex renin and AT1R increased significantly in the HS and HS+H groups. Urinary protein was positively correlated with renal renin and AT1R levels. However, in the HS+E and HS+V groups, enalapril and valsartan failed to influence renal renalase expression but abolished the increase in proteinuria, renal cortex renin, and AT1R levels with respect to the HS group. CONCLUSION This study indicates that high salt intake reduces renal expression, and renal RAS may be not involved in the regulation of renalase in SD rats fed with high-salt diet.