The effects of endothelin-1 on flap necrosis.

In reconstructive surgery, flap necrosis is a major obstacle. The vasospasm in microvascular circulation can be one of the causes of flap necrosis. The vascular endothelium has an important role in the regulation of vascular tone by producing vasodilating and vasoconstricting factors. Endothelin-1, a 21-amino acid polypeptide isolated from the vascular endothelium, is reported to be one of the most potent vasoconstrictors. The purpose of this study was to determine the significance of endothelin-1 on flap necrosis using a rat skin flap. First, we introduced into the experiment endothelin-1 and ETA receptor antagonists, FR139317, then we tried to determine the time course changes of endothelin-1 levels in the flap. Endothelin-1 antagonist had no effect on survival length, although endothelin-1 injection clearly reduced survival length. The combined treatment of antagonist and injection suppressed the effect of endothelin-1 in reducing survival length. Endothelin-1 levels in the flap base significantly increased from 6 hours, and its levels in the flap periphery presented no remarkable changes. These results may suggest that endothelin-1, especially that produced in the flap base, exerts a major effect on flap microcirculation.