Ice-water hand immersion causes a reflex decrease in skin temperature in the contralateral hand.

Cutaneous receptors stimulated by ice-water immersion of one hand will increase sympathetic nerve activity to the palm skin in the nonimmersed contralateral hand and reduce blood flow, reflecting on a decrease in skin surface temperature under a constant ambient environment. To test the hypothesis that gender might affect the contralateral vasoconstrictor response, we analyzed the spatiotemporal pattern of palm skin surface temperature during ice-water immersion for 10 min using thermography in eight males and eight females. As soon as the left hand was immersed in ice-water, palm skin temperature in the nonimmersed right hand quickly decreased in all subjects, particularly in the periphery of the digits and palm. The reduction in skin temperature was short-lasting in 63% of males and 38% of females, but it lasted throughout immersion in the remaining subjects. The average decrease in palm skin temperature was not significantly different between males and females, though it tended to be greater in males. The mean arterial blood pressure significantly increased and heart rate decreased during immersion in males, whereas no substantial cardiovascular changes were observed in females. Cold sensation was well coincident with the appearance of a reduction in the palm skin temperature. In consideration of all these results, we suggest that cutaneous cold stimuli increased skin sympathetic nerve activity in the nonimmersed hand and reduced skin blood flow. We also contend that gender difference in the contralateral vasoconstrictor response was denied because the time course and magnitude of the decrease in palm skin temperature were not different between males and females.