Renin-angiotensin system gene expression in the kidney and in the heart in hypertensive ISIAH rats

Abstract

The content of mRNA of renin-angiotensin system (RAS) genes in the kidney and heart of hypertensive ISIAH and normotensive WAG rats was measured by the real-time PCR. Statistically significant decrease of RAS gene mRNA was registered in the kidney of ISIAH rats, including Ren (by 45%), Ace (43%), AT1A (34%), COX-2 (50%). In the myocardium AT1A mRNA expression decreased by 28% while Ace mRNA expression increased by 80%. These results demonstrate the reduction of renal RAS basal activity in the hypertensive ISIAH rats, and this allows us to consider the ISIAH rat, as a low-renin hypertensive strain. In support of this viewpoint, in the ISIAH rats, a two-fold increase in the connective tissue sodium concentration as well as statistically significant plasma sodium increase (from 136 +/- 0,25 micromol/l in WAG to 139 +/- 0,3 micromol/l in the ISIAH rats) were found. Our conclusion backed by a tendency of the ISIAH plasma aldosterone level decrease giving in sum a classical picture of a low-renin hypertensive state in the ISIAH rats. It was suggested that the formation of low-renin arterial hypertension in the ISIAH rats may depend on changes in kidney ion channels function. In addition, renal NO system alterations could be also involved in the pathogenesis of arterial hypertension in the ISIAH rats.