The salvage of rabbit ischaemic epigastric free flaps using the vasodilator calcitonin gene-related peptide

Abstract

The rabbit epigastric free flap, subjected to 21 hours of warm (25°C) ischaemia, was used as an experimental model to test the ability of two endothelium-dependent vasodilators, calcitonin gene-related peptide (CGRP) and carbamyl β-methylcholine chloride (MCh, bethanechol chloride, the stable acetylcholine analogue) to improve flap viability. After the period of ischaemia, flaps were infused intra-arterially with either Hanks balanced salt solution (controls), CGRP or MCh for 30 minutes, and received additional intravenous boluses of these drugs at 2 and 32 minutes after revascularisation. The area of flap surviving improved significantly (p < 0.025) from 39.9% (n = 18) for controls to 70.2% (n = 14) for CGRP treatment at 2 μg/kg, but was unchanged at 47.1% (n = 14) for MCh treatment at 50 μg/kg. Both CGRP and MCh significantly increased blood flow (p < 0.05) resulting in 34% lower peripheral resistances compared with controls. These results suggest that CGRP has considerable clinical potential for the salvage of ischaemic flaps. CGRP must have several, as yet undefined, beneficial effects on the ischaemic tissue, since MCh invoked a vasodilatory response but failed to salvage ischaemic flaps.