Effects of adrenomedullin and calcitonin gene-related peptide on contractions of the rat aorta and porcine coronary artery

摘要

Effects of adrenomedullin and α-calcitonin gene-related peptide(CGRP) on the contractions and cytosolic Ca~2+ concentrations ([Ca~2+]I) of the rat aorta and porcine coronary artery wee investigated. Characteristics of the receptors mediating the effects of adrenomedullin and α-CGRP were also Investigated. Adrenomedullin and α-CGRP caused a concentration-dependent relaxation in the rat aorta Contracted with noradrenaline. The IC_50 values for adrenomedullin and α-CGRP were 2.4 nM and 4.0 nM, respectively. The relaxant effects of these peptides were abolished by removal of the endothelium and significantly attenuated by an inhibitor of nitric oxide synthase, N~G-monomethyl-L-arginine(L- NMMA, 100 μM), but not by a cyclo-oxygenase inhibitor, indomethacin (10 μM).