Cerebral involvement in dehydration-induced natriuresis.

Water deprivation caused daily urinary Na output to more than double in normal sheep, but caused no increase in Na excretion in sheep (A3VL-sheep) in which the anterior third ventricle wall had been ablated. Dehydrated A3VL-sheep exhibited a much greater degree of hypernatremia than dehydrated normal sheep, although water losses were similar in both groups. We postulate that the natriuresis induced by dehydration is a cerebrally mediated homeostatic response.