Effect of rate of change in skin temperature on local sweating rate.

To evaluate the relative contributions of positive and negative variations of mean skin temperature (+/- dTsk/dt) on thermoregulatory responses, male resting nude subjects were exposed to rapid or slow alterations in air and wall temperatures (28--45 degrees C; Pa = 20.0 mbar). Rates of heating-cooling cycles were equal to dTa/dt = +/- 3.40, 1.13, 0.57, 0.38, or 0.19 degrees C/min. Continuous measurements were made of rectal, oral, ear, and mean skin temperatures and of arm sweating (dew-point hygrometer method). During all exposures the local skin temperature was kept constant (Tsl = 39 degrees C). The results showed that peripheral inputs are a major factor in thermoregulatory processes. Cutaneous receptors produce a positive and a negative rate component within the central thermal integrator. A higher rate threshold was observed for the positive rate component than for the negative one.