Rate and Extent of Adaptive Cardiovascular Changes in Rats during Experimental Renal Hypertension

Abstract

Abstract To study the extent and exact time course of cardiovascular structural adaptation to increases in pressure load, renal hypertension was induced in normotensive male Wistar rats by renal artery constriction. At different intervals after operation the hemodynamic characteristics of the hypertensive rats and normotensive control rats were explored in paired hindquarter perfusions, from maximal dilatation up to maximal constriction ( cf , Folkow et al , 1970 b). At the same time intervals the extent of left ventricular hypertrophy and of water content of the aortic wall were examined. The results reveal the presence of left ventricular hypertrophy in the hypertensive rats already after one week, soon followed by adaptive structural changes of the resistance vessels, in the form mainly of media hypertrophy, these processes being largely completed 2–3 weeks after operation. In these animals, lacking genetic predisposition for hypertension, the extent of the structural vascular changes seems large enough to explain a considerable part, but not all, of the pressure rise. An increased water content of the hypertensive aortic wall is found first 4.5 months after operation, indicating that some water logging of arterial and maybe also arteriolar walls might occur in late phases of chronic renal hypertension.