Time course of blood changes during acute water deprivation in rats

Abstract

Two experiments described the onset of hyperosmolality and hypovolemia which occur during the first 24 hr of water deprivation and during periods of extended deprivation up to 72 hr. The first measurable increase in plasma osmolality and decrease in volume were coincident and occurred between 4–8 hr of deprivation, which corresponds to data concerning drinking behavior collected under similar conditions. The first reliable body weight loss occurred between 8 and 24 hr deprivation. Reliable body weight losses, but no further significant blood changes occurred between 48–72 hr water deprivation. A third experiment found increases in plasma osmolality to occur as rats aged from 85 to 100 days, and corroborated earlier findings of plasma volume decreases at that age period.