Splanchnic and cerebral vasodilatory effects of calcitonin gene-related peptide I in humans

Theability ofsynthetic humancalcitonin gene-related peptide (CGRPI)toactasanarterial vasodilator wastested inhealthy menbymeasuring arterial blood flow parameters incarotid, superior mesenteric, celiac, andfemoral vessels. Calculated volume flow wassignificantly increased (140± 21%ofbasal) inthe SMAwith a2-ng/kg/min infusion ofCGRP.Carotid artery volumeflow increased dosedependently (96±6%,122±15%,135 ± 15%ofbasal, respectively, with2,4,or8ng/kg/min). With steady-state infusion, carotid andsuperior mesenteric arterial flow parameters remained significantly elevated for30minutes after cessation ofpeptide administration. Bloodpressure was unchanged. Pulse increased dosedependently. Arterial diameters wereunchanged, implying activity atthearteriolar level. C ALCITONIN GENE-RELATED PEPTIDE (CGRP)is anovel peptide resulting fromalternative processing ofcalcitonin genetranscripts. 'Inthyroid C cells, mRNA encoding forcalcitonin isproduced, whereas mRNA forCGRPpredominates innervous tissues. Calcitonin gene-related peptide iswidely distributed inavariety ofneuronal tissues inboththecentral and peripheral nervous systems andisparticularly abundant inperivascular nerves.2 Thepeptide hasbeendemonstrated immunohistochemically inclose association with