Effects of aspirin on renal sodium excretion, blood pressure, and plasma and extracellular fluid volume in salt-loaded rats.

The effect of aspirin administration and presumed blockade of prostaglandin synthesis on renal sodium excretion, plasma and extracellular fluid volumes, and blood pressure were examined in rats on a high sodium intake. After acute salt loading aspirin treated rats showed an impaired sodium excretion, while no changes in glomerular filtration rate were observed. In chronically loaded rats (7 weeks) administration of aspirin induced significant increases in both plasma and extracellular fluid volume, but no significant changes in blood pressures were found. The results are consistent with the hypothesis that prostaglandins mediate renal sodium excretion and therefore participate in extracellular fluid volume regulation.