CALCITONIN-GENE-RELATED PEPTIDE IN EXPERIMENTAL-ISCHEMIA - IMPLICATION OF AN ENDOGENOUS ANTIISCHEMIC EFFECT

Ischemia resulting from flap harvesting and vascular manipulation duri ng microsurgery may be responsible for flap ischemic sufferance and, u ltimately, necrosis. Recently, the regulatory role of the sensory nerv ous system in ischemia has attracted much interest. Calcitonin gene-re lated peptide (CGRP), a neuropeptide, is a naturally occurring vasodil ator with no constrictive effects. In the present study, we developed a model of partial, chronic ischemia in the rat epigastric flap and in vestigated the effects of ischemia on concentrations of CGRP-like immu noreactivity (-LI) in ischemic skin and in different regions of the ra t brain (striatum, hippocampus, pituitary, hypothalamus, and frontal a nd occipital cortex). A neurovascular island flap based on the superfi cial epigastric vessels was raised in 10 animals. Ischemia of the flap was obtained by ligating the feeding artery so that the blood flow wa s reduced to 25% of the normal circulation. An electromagnetic Doppler positioned on the artery was used to monitor the blood flow reduction . Ten nonoperated animals were used as controls. Ten days after the op eration, CGRP-LI was significantly increased in five of six brain regi ons analyzed (striatum excepted). Significantly decreased concentratio ns of CGRP-LI were found in seven ischemic flaps, as opposed to the co ntrol group. In the remaining three flaps, no significant changes in C GRP concentration were observed. The highest blood flux values (detect ed using a laser Doppler) in the flaps correlated positively with the highest concentrations of CGRP-LI in the nap tissue. The results of th e present study suggest that endogenous CGRP may be involved in the ad aptive response to ischemia.