Pentobarbital potentiates natriuretic response to acute volume expansion in monkeys

We determined the influence of pentobarbital sodium on the renal responses of the monkey to acute intravascular volume expansion. Before volume expansion, the anesthetized animals had a significantly lower blood pressure and creatinine clearance and a significantly higher urine flow and sodium excretion than the conscious animals. After volume expansion with an isotonic, isoncotic, dextran solution, sodium excretion and urine flow increased significantly in both groups of animals. However, both responses were significantly greater in the anesthetized animals. The greater natriuresis in the anesthetized animals was associated with a greater fractional sodium excretion than in the conscious animals. The potentiated response of the anesthetized animal may be the result of a direct renal tubular effect of pentobarbital and/or the result of the anesthetic removing an inhibitory influence on sodium excretion.