Effect of subarachnoid hemorrhage on calcitonin gene-related peptide-induced relaxation in rabbit basilar artery.

An isometric tension measurement of ring segments was performed in the rabbit basilar and common carotid arteries in vitro to investigate the regional differences in the calcitonin gene-related peptide (CGRP)-induced vasodilation and the effect of subarachnoid hemorrhage on CGRP-induced vasodilation. CGRP elicited vasodilation of the rabbit basilar artery in a dose-dependent fashion when the artery was precontracted by 10(-5) M 5-hydroxytryptamine, whereas almost no relaxation occurred in the rabbit common carotid artery. The relaxation of the basilar artery was 64.03 +/- 1.85% at 3 x 10(-8) M CGRP, with an EC50 of 8.46 +/- 0.08. Two days after experimental subarachnoid hemorrhage, CGRP-induced relaxation of the rabbit basilar artery was 53.96 +/- 8.08% of the 10(-5) M 5-hydroxytryptamine-induced contraction, not significantly different from that of the basilar artery of the control rabbit. Our findings suggest that CGRP induces potent vasodilation in the rabbit basilar artery and that no impairment of vasodilation occurred after experimental subarachnoid hemorrhage. We speculate that CGRP may have therapeutic potential in cerebrovascular disease such as vasospasm after subarachnoid hemorrhage.