Prostaglandin synthesis and renal function in man.

1. Experiments were performed to determine the changes in renal function which occur following prostaglandin synthetase inhibition in healthy conscious humans. It was hoped that such experiments could provide information on the mechanism by which renal prostaglandin synthesis influences urinary excretion. 2. In water-diuretic male subjects (receiving a slow saline infusion) the renal excretion of sodium and water was reduced following I.V. acetylsalicylic acid (1 g) administration, while the effective renal plasma flow (p-aminohippurate clearance), and glomerular filtration rate (inulin clearance) remained unaltered. 3. In normally hydrated female subjects on an unrestricted diet, the mean urinary prostaglandin E output was 8.5 ng/hr. The renal excretion of sodium, water and urinary prostaglandin E were significantly reduced (P less than 0.05) following oral acetylsalicylic acid (1.2 g) administration. 4. In normally hydrated female subjects on an unrestricted diet the renal excretion of sodium and water was reduced following oral paracetamol (1.5 g) administration. 5. It is concluded that following renal prostaglandin synthetase inhibition in conscious humans, the excretion of sodium and water can be reduced without measurable changes in the glomerular filtration rate or effective renal plasma flow. It is suggested that in conscious healthy humans, the kidney may continually synthesize prostaglandin which might help to maintain sodium and water excretion by a direct action on the renal tubule without influencing renal blood flow. The relevance of this hypothesis to the intrarenal location of prostaglandin synthetase is discussed.