Effects of changing hypothalamic temperature on eccrine sweating in the patas monkey.

Two male (10-13 kg) patas monkeys (Erythrocebus patas) were implanted with bilateral thermodes to control hypothalamic temperature. Animals were restrained in primate chairs and instrumented to yield hypothalamic (THYPO), colonic (Tc), and mean skin (Tsk) temperatures, chest sweat rate (mSW), and heart rate (HR). THYPO was monitored using a thermocouple inserted to the tip of a non-perfused thermode; mSW was measured using resistance hygrometry. After the monkey equilibrated to a selected ambient temperature, four thermodes were perfused with water from a temperature-controlled bath. Increasing THYPO from 37 to 41 degrees C increased mSW from 0.05 to 0.30 mg.cm-2.min-1. Reducing Tsk shifted the THYPO:mSW relationship to the right (p less than 0.05) without significantly altering its slope. Activity-induced changes in HR, when THYPO was constant, caused fluctuations in ongoing sweating that closely tracked HR. We conclude that mSW in the patas monkey is controlled by both peripheral and central thermal inputs and nonthermal factors.