NONNEURAL MEDIATION OF DIGITAL VASODILATION DURING MENOPAUSAL HOT FLUSHES

Menopausal hot flushes are accompanied by profuse sweating, decreased skin resistance, modest tachycardia and cutaneous vasodilation. With t he exception of the last effect, these events are consistent with an a brupt increase in sympathetic outflow. Blood flow in the human finger is controlled through sympathetic vasoconstricting nerves, and increas ed sympathetic activation results in digital vasoconstriction. We ther efore sought to determine if digital vasodilation during hot flushes w as mediated through efferent sympathetic nerves. Bilateral finger temp erature and blood flow were recorded after the digital nerves on one h and had been blocked with a local injection of lidocaine. The effectiv eness of the nerve blocks was verified by a reflex vasoconstriction te st. Hot flushes were objectively defined using skin conductance respon ses recorded from the sternum. Fifteen hot flushes occurred in 8 women . Significant elevations in finger temperature and blood flow occurred during the flushes, in nerve-blocked and intact fingers. These findin gs suggest that digital vasodilation during hot flushes is due to a ci rculating vasodilating substance.