THE EFFECT OF MECLOFENAMATE ON RENAL BLOOD-FLOW IN THE UNANESTHETIZED DOG - RELATION TO RENAL PROSTAGLANDINS AND SODIUM-BALANCE

Abstract

The effects of sodium meclofenamate (5 mg/kg i.v.), an inhibitor of prostaglandin [PG] synthesis on renal function were compared in 6 unanesthetized dogs maintained for 5-7 days before the experiment on 100 meq/day of NaCl and after Na-depletion by furosemide administration and salt deprivation. Plasma renin activity (PRA) during Na-depletion (12.35 .+-. 3.93 ng/ml per h) was higher than during Na-repletion (1.46 .+-. 0.47 ng/ml per h; P < 0.05). The administration of meclofenamate did not alter mean arterial pressure, renal blood flow, urine volume, excretion of Na and K or PRA in the Na-replete dog. During Na-depletion, meclofenamate reduced renal blood flow from 168 .+-. 35 to 105 .+-. 23 ml/min (P < 0.01) and urine flow from 0.32 .+-. 0.09 to 0.16 .+-. 0.05 ml/min (P < 0.05), but did not affect mean arterial pressure, electrolyte excretion or PRA. The meclofenamate-induced reduction in renal blood flow during Na-depletion was correlated with control PRA. After administration of meclofenamate, the urinary excretion of immunoreactive PGE2 fell by 66% (P < 0.05) in the Na-replete dog and by 72% (P < 0.05) in the Na-depleted dog. The effects of meclofenamate on renal hemodynamics vary with the state of Na balance and in relation to PRA.