Human and rat alpha-CGRP but not calcitonin cause mesenteric vasodilatation in rats.
A single gene encodes both calcitonin and the calcitonin gene-related peptide (CGRP). Human and rat alpha-CGRP were compared with sodium nitroprusside in the rat and rabbit isolated mesenteric vascular preparation perfused at constant flow. In the presence of the vasoconstrictor noradrenaline (10(-5) M), rat alpha-CGRP was about 10 times as potent as either human alpha-CGRP or sodium nitroprusside as a vasodilator in the rat mesenteric vasculature. In the rabbit mesenteric vasculature the order of potency was rat alpha-CGRP greater than human alpha-CGRP greater than sodium nitroprusside. Human and salmon calcitonin showed no vasodilator activity at doses 100 times greater than human alpha-CGRP. These results show that human and rat alpha-CGRP are potent vasodilators in the mesenteric vasculature, an effect not mimicked by the alternative gene product, the plasma calcium lowering hormone calcitonin.
D000818:Animals; D002116:Calcitonin / Q000494:pharmacology*; D015740:Calcitonin Gene-Related Peptide; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D009419:Nerve Tissue Proteins / Q000494:pharmacology* / Q000502:physiology; D009599:Nitroprusside / Q000494:pharmacology; D010477:Perfusion; D011817:Rabbits; D051381:Rats; D011919:Rats, Inbred Strains; D013045:Species Specificity; D013152:Splanchnic Circulation / Q000187:drug effects*; D014664:Vasodilation / Q000187:drug effects*
D009419:Nerve Tissue Proteins; D009599:Nitroprusside; D002116:Calcitonin; D015740:Calcitonin Gene-Related Peptide