Sex difference of arterial response to cold exposure

Abstract

Objective: Hypersensitive aesthesia for coldness is known to occur more frequent in women. We hypothesized that it is derived from sex difference of vascular response to coldness. In order to confirm this hypothesis, we examined the arterial response to cold exposure in rat hindlimbs. Methods: Male (M), female (F) and ovariectomized (OVX) Wistar rats were used. Cold exposure was induced by cooling spray on the hindlimb. Tissue temperature was recorded using digital thermometer after cold exposure. Synchrotron radiation microangiography (SRA) with a resolution of 26 um was employed for the measurement of arterial diameter. Timing of imaging was pre and one minute after cold exposure. Results: The reduction in temperature was significant in F and OVX compared with M (p<0.01). SRA showed that arteries of hindlimbs are dilated by cold exposure in all groups. Percentage of arterial dilatation in response to cold exposure was statistically small in F compared with M and OVX (69+/−40% (F), 118+/−73% (M), 99+/−42% (OVX), p < 0.05 vs F, respectively). Conclusion: Although it has been recognized that cutaneous vessels are constricted by cold exposure, the reaction of deep vessels of lower limbs were not investigated in association with gender difference. From this experiment, it is clarified that female arteries are less expansive, and existence of ovarian hormones disturbed the dilation of arteries against cold exposure.