COMPARISON OF VASCULAR EFFECTS OF CALCITONIN-GENE-RELATED PEPTIDE ANDLIDOCAINE ON HUMAN VEINS

Arterial and venous constriction during microsurgery are among the lea ding causes of flap failure. So far pharmacologic tools have been prop osed only for arterial constriction, and local anesthetics are commonl y used to counteract the vascular spasm. The purpose of this study was to investigate the vascular effects of two known arterial vasodilator s on human veins, in order to evaluate the possibility of their potent ial use during microsurgery. In vitro experiments were performed on 31 greater saphenous vein (SV) rings obtained from 20 patients and on 12 cephalic vein (CV) rings from 7 patients. The rings were mounted in o rgan baths and their isometric contractile activity was measured. Expe riments were conducted by cumulatively adding calcitonin gene-related peptide (CGRP) or lidocaine to the organ baths. The endothelium was me chanically removed in 18 SV rings and in 6 CV rings. Results demonstra ted that in vitro CGRP produced vasodilation only; no constrictive eff ects were seen. Lidocaine produced a biphasic response with contractio n at low concentrations (1.5 x 10(-5) M, 1.5 x 10(-3) M) and release o f the maximal contraction at higher concentrations, similar to that ob served in arteries. Removal of the endothelium did not significantly a ffect contractile activity in either CGRP- or lidocaine-treated vessel s. The data supported the conclusion that CGRP could be used to reliev e venous constriction, and it is suggested that further studies on the clinical use of CGRP in microsurgery is warranted.