Renal function in conscious rats after indomethacin. Evidence for a tubular action of endogenous prostaglandins.

Abstract

Conscious rats, with implanted carotid arterial cannulae, received a saline infusion (5.8 ml/h) via a tail vein for a 6 h period. The urinary excretion of water, Na, K, urea and the osmolal output were monitored, together with the systemic blood pressure. Glomerular filtration rate (inulin clearance) and effective renal plasma flow (p-aminohippurate clearance) were also measured. Four hours after the start of the infusion, indomethacin (10 mg/kg body weight) in buffered saline, or buffered saline alone, was administered via the tail vein. Following indomethacin administration, urine flow, Na output and osmolal output were markedly reduced (P < 0.01). There were no measurable changes in the systemic blood pressure, glomerular filtration rate, or effective renal plasma flow. The changes in urinary excretion observed after indomethacin are not dependent on changes in effective renal plasma flow or glomerular filtration; indomethacin apparently inhibits the synthesis of endogenous prostaglandins which directely influence renal tubular function.