Effect of acetylsalicylic acid and of indomethacin on diuresis in man: the role of cyclo-oxygenase inhibition.

The effect of acetylsalicylic acid (ASA, 3 g/day for 3 days) and of indomethacin (IND, 150 mg/day for 3 days) on diuresis and on the excretion of prostaglandin E2 (PGE2) was studied in six healthy, male volunteers. After overnight deprivation the subjects received an oral water load (20 ml/kg) and hourly urine volumes were replaced by an equivalent volume of water by mouth for 4 h. Pretreatment with both ASA and IND induced a comparable suppression (P less than 0.05 to less than 0.001) in the excretion of PGE2, but only IND also reduced (P less than 0.05) diuresis, free water clearance and the excretion of sodium. The excretion of creatinine was uninfluenced by both ASA and IND. These data indicate that a mechanism other than cyclo-oxygenase inhibition is involved in the effect of IND and ASA on diuresis in man.