Our purpose of this project was to establish that the modified microdialysis method for measuring sweat rate (SR) could assess sweat gland function by multiple-administration of acetylcholine. In the first project, two microdialysis membranes were inserted intradermally in healthy 6 subjects (3 males and 3 females; ages 21-35). SR was independently measured over each membrane. At 5 min increments, 1×10⁻⁶M to 1×10⁻¹M acetylcholine in Ringer's solution (6 doses) were administered through the microdialysis membranes. Linear regression of SR between sites revealed a strong linear relationship (slope=1.03±0.14, R=0.99±0.001, p<0.05), verifying the repeatability of the method. Sixteen subjects (8 males and 8 females; ages 21-75) participated in the second project which one membrane was perfused through the microdialysis membrane with 1×10⁻⁶ to 1 M acetylcholine in Ringer's solution (7 doses). Clear dose-response curve was observed and the acetylcholine concentration threshold for the onset of sweating ranged 1×10⁻⁶M to 1×10⁻³M. SR in the older group failed to increase with increasing acetylcholine concentration above 1×10⁻³M and was remarkably lower at 1×10⁻¹ and 1M than in the young group. However gender-related difference was not observed at any concentrations. These data accord with previous studies, suggesting that intradermal microdialysis coupled with capacitance hygrometry is a viable method of assessing sweat gland function in vivo and useful methodology for comparative studies.

DESCENTE SPORTS SCIENCE Vol.21/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE