AGING AND SEVERITY OF HYPERTENSION ATTENUATE ENDOTHELIUM-DEPENDENT RENAL VASCULAR RELAXATION IN HUMANS

Endothelial dysfunction may be related to cardiovascular risk factors, such as aging, hypertension, and atherosclerosis. We investigated whe ther aging and hypertension independently alter endothelial function i n the renal circulation in humans in the absence of abnormalities in l ipid and glucose metabolism. L-Arginine (500 mg/kg over 30 minutes) wa s intravenously administered to 33 patients with essential hypertensio n and 35 normotensive subjects. The L-arginine-induced increases in re nal plasma flow (10.1+/-0.8% versus 15.8+/-0.9%, P<.05) and plasma cGM P (53+/-4% versus 82+/-5%, P<.05) were significantly smaller in patien ts with essential hypertension than in the normotensive subjects. Mult ivariate stepwise regression analysis showed that age (P<.0002) and th e mean blood pressure (P<.0001) were independently and negatively corr elated with the renal plasma flow response to L-arginine, Age (P<.002) , mean blood pressure (P<.0001), and male six (P < .05) were independe ntly correlated with the L-arginine-induced increase in plasma cGMP. T he peak change in plasma cGMP was significantly correlated with the L- arginine-induced increase in renal plasma flow (r=.63, P<.001). These findings suggest that aging and hypertension may independently impair endothelium-dependent renovascular dilation and that this effect may b e caused at least in part by a decrease in nitric oxide production.