The Role Of Cholesterol On The Pressure Sensing Ability Of Kidneys In Rats

Abstract

We studied the effect of hypercholesterolemia on the pressure-sensing and regulating ability of the kidneys, using an acute hemorrhage model to provide 40% and 60% reduction in the blood pressure of hypercholesterolemic and control rats. The control group (n = 22) was fed a normal rat pellet diet and tap water; the experimental group (n = 22) received a diet containing 2% cholesterol/0.2% thaurocholate. Half the animals were subjected to 6 mL/kg bw and the others to 12 mL/kg bw of bleeding for 1 min. Blood pressure recording and proper samplings were done before bleeding and during the 20 min posthemorrhagic period for analysis. Despite a finding of hypercholesterolemia in the experimental group, kidney cholesterol content as well as its function remained unchanged. Following an initial 40% decrease in rats bled 6 mL/kg bw, 20 min later the mean blood pressure returned to 90% of its initial value in control rats and to 70% of its basal level in hypercholesterolemic rats. A similar delay in pressure normalization occurred in rats subjected to 12 mL/kg of bleeding. Plasma renin activity remained unaffected. We conclude that dietary hypercholesterolemia delays the normalization of blood pressure after hemorrhage without affecting the sensing ability of kidneys, and that the kidneys are less sensitive than other organs to plasma cholesterol levels. © 2011 by Walter de Gruyter GmbH & Co. All rights reserved.