Blood changes in water deprived rats.

To study the variations of blood constituents during water deprivation, rats were deprived of water from six to twelve days. Control and rehydrated animals were also included in the study. A significant increase was observed in sodium, chloride and hematocrit throughout the experiment. Calcium, bicarbonate and PCO2 increased at 10-11 days of treatment. Potassium, inorganic phosphorus, pH, base excess and blood buffer capacity did not change in the course of the experiment. Rehydrated animals recovered to control levels in all the studied components, except for pH and base excess, which increased somewhat. Plasma volume changes could explain only partially electrolyte variation. The "dehydration reaction" is considered to be the main mechanism responsible for these changes. Unchanged hematocrit levels in water deprived animals suggest that after 6 days of water deprivation there is no further loss of plasma water. Bicarbonate and PCO2 changes showed a good relationship and may account for unchanged pH and base excess values.