ABSTRACT

　Sweating is a vital physiological function to dissipate heat from the body during heat stresses and is known to be largely different among individuals to individuals. The purpose of the study was to investigate sweating responses and the contribution of nitric oxide synthase (NOS) enzyme activities to sweating during a passive heating in subjectively good sweaters (Subjective sweaters) and poor-sweaters (Subjective poor-sweaters).Eight subjective Sweaters and 7 poor-sweaters were passively heated until an oral temperature was elevated to 1.0℃ above baseline resting. Forearm sweat rate was measured at two skin sites continuously perfused with either lactated Ringer's solution (Control) or 10mmol/L NG-nitro-L-arginine methyl ester (L-NAME, non-selective NOS inhibitor) via intradermal microdialysis. Sweat rate at L-NAME site was attenuated relative to the Control in both Subjective sweaters and poor-sweaters (P<0.05). The sweat rate on both Control and L-NAME sites achieved during passive heating were similar between the groups (P>0.05). The magnitude of oral temperature elevation at 40min of the heating which maybe an index of heat-diseases risk were similar between Subjective sweaters and poor-sweaters. Mean skin temperature, mean body temperature, and heart rate during passive heating were not different between the groups. These results suggest that the subjective difference in sweaters or poor-sweaters do not affect sweating response and its underlying mechanisms associated with NOS during a passive heating. In addition, the subjective difference in sweating response is unlikely affecting an index of heat-related disease assessed from a magnitude of oral temperature elevation during passive heating. Further studies are required to determine the method to classify subjective sweaters and poor-sweaters as well as establishing a better heating protocol.

DESCENTE SPORTS SCIENCE Vol.39/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE