Arterial Relaxation Mediated by Endothelium-Derived Hyperpolarizing Factor in Hypertension Induced by Chronic Inhibition of Nitric Oxide Synthesis

Abstract
The aim of this study was to evaluate arterial relaxation mediated by endothelium-derived hyperpolarizing factor (EDHF) during chronic inhibition of nitric oxide (NO) synthase. We measured the isometric tension of isolated mesenteric arteries of Wistar rats administered Nω-nitro-L-arginine methyl ester (L-NAME, 100 mg/Kg/day) for 3 weeks. Relaxation to acetylcholine (ACh) was reduced in L-NAME treated rats (maximum relaxation, 52% versus 79%). After acute superfuison of 1x10-4 M L-NAME, half the relaxation was inhibited in controls, while the relaxation was not changed in L-NAME treated rats. In contrast, relaxation to