Intracranial osmoreceptors control evaporation in the heat-stressed cat.

During heat stress, most mammals regulate body temperature by evaporating body water. Dehydrated mammals reduce their evaporative water losses and allow body temperature to rise. The physiological mechanism underlying this inhibition of evaporative cooling in dehydration have remained unclear. We now report that the rate of evaporation in dehydrated, heat-stressed cats is controlled by intracranial osmoreceptors and suggest that these receptors are part of a common central neural osmoreceptive mechanism regulating evaporative heat loss, renal water loss and thirst.