Differential contribution of endothelium-derived relaxing factors to vascular reactivity in conduit and resistance arteries from normotensive and hypertensive rats

ABSTRACTThe endothelium contributes to the maintenance of vasodilator tone by releasing nitric oxide (NO), prostacyclin (PGI2), and endothelium-derived hyperpolarizing factor (EDHF). In hypertension, endothelium-dependent relaxation is attenuated (a phenomenon referred to as endothelial dysfunction) and contributes to the increased peripheral resistance. However, which vasodilator among NO, PGI2, and EDHF is impaired in hypertension remains largely unknown. The present study was designed to study the exact contribution of NO, PGI2, and EDHF to vascular reactivity in conduit and resistance artery, under physiological and pathological conditions. The aorta and the second-order mesenteric artery from spontaneous hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats were used to measure the vasorelaxation with myograph technology, in the presence or absence of different inhibitors. The results showed that the endothelium-dependent vasodilatation in the conduit artery was mediated mainly by NO, whereas the resis...