Local skin temperature may be a modulator of sweat gland function but the mechanism is unclear. PURPOSE: To examine the role of local skin temperature in modulating local sweating rate (LSR) using a model of sweat gland activation that produces a moderate, physiologically based sweating response. METHODS: Each subject (n=15) was instrumented with 7 skin temperature probes ( skin), an esophageal probe (Tcore), and a sweat rate capsule (dorsal forearm). A LSR was produced by 30 s of intradermal electrical stimulation (5 mA, 0.2 to 64 Hz) that resulted in release of ACh from the sudomotor nerve and produced a transient sweating response lasting 60 to 90 s. To modify local skin temperature the subjects sat in an environmental chamber for 60 min at three different ambient temperatures (Ta): 21, 27, and 34 °C, on the same day without moving the sweat capsule. Subjects acclimated to the chamber temperature for 45 min prior to producing the LSR. The LSR was quantified as the area-under the sweat rate-time curve (LSR AUC, normalized to peak LSR AUC at 21°C ) and curve fit using a four parameter logistic model. RESULTS: Local skin temperature averaged 29.3 ± 1.2, 31.3 ± 0.8, and 34.6 ± 0.8°C, baseline sweat rate (SR) averaged 0.127 ± 0.05, 0.142 ± 0.065, and 0.124 ± 0.083 mg • min-1 • cm-2 and Tcore averaged 37.1 ± 0.7, 36.8 ± 0.6, and 36.6 ± 0.5°C at 21, 27, and 34°C Ta, respectively. Comparison of the models indicated that the both the plateau LSR AUCX and the EC50 at 21, 27 and 34°C were not the same (p=0.0022). The onset of sweating occurred sooner at 34°C (4.6 ± 2 s) than at 21°C (7.3 ± 3.0 s) or 27°C (6.1 ± 2.0 s) and was linearly related to local skin temperature (p = 0.0002). Finally, the increase in sweating rate at 34°C (0.032 ± 0.027 ∆SR•s-1) was also faster than at 21 or 27°C (pCONCLUSION: The observed change in the stimulus-response characteristics of the LSR induced by intradermal electrical stimulation (decreased EC50 and increased plateau LSR AUC) supports the hypothesis that an increased local skin temperature improves the sweat gland responsiveness to ACh released by the sudomotor nerve during intradermal electrical stimulation.



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