Gender differences in cutaneous laser Doppler flow response to local direct and contralateral cooling

To investigate the role of sympathetic neurovascular reactivity in the gend er differences of cutaneous, cold-induced vasomotor response, we compared d irect (at the site of cooling) and indirect (at a site remote from the cool ing site) response measured by laser Doppler (LD) flowmetry in 12 healthy m ales and 12 healthy females. The females underwent testing twice, once in t he follicular and once in the luteal phase of the menstrual cycle, We measu red LD flow before and during local cooling of one hand at 15 degrees C. We found that local cooling evokes a significantly greater decrease in cutane ous LD flow ire females than in males in direct as well as in indirect resp onse conditions (p < 0.05). Comparing the response in females in the differ ent phases of menstrual cycle, we obtained a significantly greater direct r esponse to local cooling in the luteal phase than in the follicular phase ( p < 0.05). In contrast, there was no menstrual-cycle-dependent difference i n the indirect response to cold. The results of our study strongly indicate that sympathetic neural reactivity, as assessed by way of an indirect resp onse to a cold stimulus, significantly contributes to gender differences in the response to local cooling. In contrast, the variation in microvascular responsiveness to cold exposure due to the menstrual cycle is most probabl y caused by local vascular mechanisms rather than by variation in sympathet ic neural reactivity to local cooling. Copyright (C) 2000 S. Karger AG. Bas el.