Alteration in Contractile Response to Noradrenaline, 5-Hydroxytryptamine, Sarafotoxin 6c, and Angiotensin II in Rat Mesenteric Artery During Organ Culture

摘要

Objective To compare the vasoconstrictive effects of 9 mediators on fresh and incubated mesenteric arteries of rats. Methods The superior mesenteric artery of rat was removed and the endothelium was denuded. The vessels were cut into 1 mm long cylindrical segments and subjected to organ culture for 24 hours. Fresh or incubated segments were immersed into tissue baths and the concentration-response curves were obtained by cumulative administration of the vasoconstrictors. Results In fresh mesenteric artery, endothelin-1 (ET-1), 5-hydroxytryptamine (5-HT), noradrenaline (NA), 5-carboxamidotryptamine (5-CT), and angiotensin n (Ang II) induced potent and sustained constrictions in a concentration-dependent manner. The contraction induced by sarafotoxin 6c (S6c) was weak, while bradykinin (BK) , des-Arg-bradykinin (DA-BK), and human urotensin II (hUT-II) showed no detectable contraction. The concentraion-response curves in order of slopes was ET-1, NA, 5-HT, 5-CT, and Ang fl . The order of the maximum contractions was ET-1 > NA = 5-HT = 5-CT> Ang II >S6c. After organ culture, the concentration-response curves induced by S6c, NA, and 5-HT were significantly increased, while that induced by Ang II was decreased as comparing to fresh arteries. BK contracted the artery only weakly. Conclusion Organ culture changed the phenotypes towards an increased efficacy of NA, 5-HT, S6c, and a reduced efficacy of Ang II , which is in accordance with the results of pharmacological characterization in some human vascular disease.