CHANGE IN DIGITAL BLOOD-FLOW WITH SIMULTANEOUS REDUCTION IN PLASMA ENDOTHELIN-INDUCED BY HAND-ARM VIBRATION

Involvement of endothelium-derived relaxing factor (EDRF) or endotheli um-derived constricting factor (EDCF) has been proposed as the pathoph ysiologic mechanism of vibration-induced white finger (VWF). Recent ev idence that endothelin is a potent vasoconstrictor peptide indicates t hat it may play a role in vasoregulation during vibration exposure thr ough the local actions of EDRF or EDCF. Therefore, we examined the eff ects of grasping (50 N) and hand-arm vibration (50 m/s(2) rms, 120 Hz, x-axis) on digital blood flow (DBF) and on the level of plasma endoth elin in seven healthy male office workers. Grasping decreased DBF with out affecting endothelin, and vibration increased DBF with a simultane ous reduction in endothelin. The grasping-induced decrease in DBF seem ed to be due to mechanical compression of the vessels. The negative co rrelation between DBF and endothelin during vibration exposure suggest s that a reduction in release of endothelin from smooth muscle into th e vessel cavity during vibration leads to vasodilatation, possibly att ributable to the local axon reflex.