Gender differences in regional cutaneous microcirculatory responses to capsaicin.

Vascular responsiveness between healthy male and female subjects to capsaicin, an agent promoting neuropeptide release, was compared. Changes in skin perfusion were measured non-invasively using laser Doppler imaging. Topical application of a 3% solution of capsaicin to the dorsum of the hand resulted in vasodilatation in nine of 10 male subjects, but in less than half of the female subjects. Responses to capsaicin at the shin were smaller but did not show gender differences. Fingertip temperature was significantly lower in females compared with males and this correlated (r = 0.54, P < 0.01) with the maximum response to capsaicin. These effects were specific to capsaicin as endothelium-dependent and -independent vasodilator mechanisms, assessed non-invasively by iontophoresis of acetylcholine and sodium nitroprusside, respectively, showed no gender differences. These findings suggest a specific anomaly in capsaicin-sensitive vasodilator mechanisms in some subjects, perhaps indicative of subclinical expression of Raynaud's phenomenon.