Calcitonin gene-related peptide delays the no-reflow phenomenon in the rat island flap

Calcitonin gene-related peptide (CGRP) is a bioactive neuropeptide with potent vasodilatory properties. The effect of CGRP on the no-reflow phenomenon was studied in rats. Island flaps based on the epigastric vessels were exposed to 11 hours of warm ischemia. CGRP was given as single doses before, before and after, or after the ischemic insults. Pre-ischemic treatment with CGRP increased flap survival at concentrations ranging from 10(-9) mol/L to 10(-7) mol/L. The survival rate of saline and untreated control flaps was 18.4%, calculated on the basis of tissue survival areas. The optimum survival rate after preischemic CGRP treatment was 60.3%, and after both preischemic and postischemic CGRP treatment, 66.3% (p less than 0.005 as compared with controls). Given as a single dose after the ischemic period, CGRP increased flap survival to 45.5% at 10(-7) mol/L (p less than 0.05), but no effect was found at lower concentrations. Apart from free radical scavengers, CGRP is the only agent known to delay the no-reflow phenomenon after a single postischemic dose.