Contraction and endothelium dependent relaxation via a adrenoceptors are variable in various pig arteries

Publisher Website
Google Scholar
Abstract
Objective: The aim was to examine differences in the vascular response to α adrenoceptor stimulation on both smooth muscle and endothelium among large arteries perfusing various organs. Methods: In ring preparations of coronary, carotid, iliac, mesenteric, and renal arteries from pigs (n=24), the magnitudes of contraction to noradrenaline (with β blocker), with or without endothelium, and endothelium dependent relaxation to noradrenaline (with α1 and β blocker) were compared in vitro. Results: In both endothelium-intact and denuded groups, the contractions to noradrenaline were significantly smaller in coronary and carotid arteries than in iliac, mesenteric, and renal arteries. The presence of endothelium significantly suppressed the contractions in coronary and carotid arteries, but did not affect the contractions in iliac, mesenteric, and renal arteries. The endothelium dependent relaxations to noradrenaline, which were abolished by LNMMA, were more prominent in coronary and carotid arteries than in iliac, mesenteric, and renal arteries. Conclusions: The contractions via α adrenoceptors were small, and endothelium dependent relaxations via α2 adrenoceptors were large, in the coronary and carotid arteries, which perfuse the vital organs (heart and brain), as compared with those in iliac, mesenteric, and renal arteries. These results suggest that in the state of activation of the sympathetic nervous system, arterial tone in response to α adrenoceptor stimulation may be regulated not only by α adrenoceptors on vascular smooth muscle but also by those on endothelium, through release of endothelium derived relaxing factor (EDRF) via α2 adrenoceptors. Cardiovascular Research 1993;27:779-784

This publication has 0 references indexed in Scilit: