Regional hemodynamic effects of calcitonin gene-related peptide.

Cardiovascular responses to infusions of rat alpha-calcitonin gene-related peptide (CGRP; 0.06, 0.6, 6.0 nmol/h) or rat alpha-atrial natriuretic peptide (ANP; 3.7 nmol/h) were measured in conscious rats. During infusion of the low dose of CGRP, when mean arterial pressure (MAP) was little affected, there were reductions in common carotid, renal, mesenteric, and hindquarter vascular resistances (the magnitude of the responses in the same descending order). However, only flow in the common carotid vessels was increased above base line. After infusion, there was a hindquarter vasoconstriction. During infusion of the higher doses of CGRP, there were dose-related decreases in MAP and increases in heart rate associated with (hyperemic) hindquarter vasodilatations and mesenteric vasoconstrictions. The common carotid vasodilatation peaked with the intermediate dose of CGRP; the changes in renal vascular resistance were not dose related. After infusion of the high dose of CGRP there were persistent (at least 60 min) common carotid and hindquarter vasodilatations and mesenteric vasoconstriction, with a transient overshoot in renal vascular resistance. Infusions of CGRP and ANP matched for their effects on MAP had similar influences on mesenteric hemodynamics, but all other variables were affected differently.