Nonadrenergic and Noncholinergic Arterial Dilatation and Venoconstriction Are Mediated by Calcitonin Gene-Related Peptide and Neurokinin-1 Receptors, Respectively, in the Mesenteric Vasculature of the Rat after Perivascular Nerve

In the present study, selective calcitonin gene-related peptide (CGRP) and neurokinin (NK) agonists and antagonists were used to characterize the receptors mediating the nerve-induced arterial vasodilation and venous vasoconstnction in the rat mesentenc vasculature. In guanethidine-pretreated preparations, penvas-cular nerve stimulation (PNS) induced a frequency-dependent vasodilation in the arterial vasculature (precontracted with meth-oxamine), yet only induced an atropine-resistant contraction in the venous mesentenc vasculature (precontracted with U46619) of the rat. hCGRPa induced a marked dose-dependent relaxation of the arterial side, whereas only a slight vasodilation was seen at a high dose on the precontracted venous side. The PNS or hCGRP0-induced arterial dilatation was markedly reduced by the antagonist hCGRP37, whereas the venoconstnctive response to PNS was not. Furthermore, [acetamidomethyl-Cys27]hCGR