The effect of indomethacin on kidney function: indomethacin and furosemide antagonism

The effect of furosemide and indomethacin on renal function was investigated in anesthetized dogs. 1. On infusing 0.05 mg/kg/min furosemide directly into the left renal artery, about 18% of the filtered water and 19% of the filtered sodium was excreted in both non-hydrated and hydrated dogs. 2. Under the effect of 0.1 mg/kg/min indomethacin administered intravenously renal blood flow decreased markedly, glomerular filtration rate remained unchanged, the filtration fraction increased. 3. Indomethacin induced a decrease in water and sodium rejection and water and sodium excretion in both the hydrated and non-hydrated animals. 4. Indomethacin inhibited the diuretic effect of furosemide in the non-hydrated animals. This effect was much weaker in the hydrated group. These data suggest that in the anesthetized dog, endogenous prostaglandins may serve to maintain renal blood flow but not glomerular filtration rate. It is concluded that the indomethacin-induced inhibition of the furosemide effect is the consequence of hemodynamic changes occurring in the kidney. The data do not support the direct physiological role of prostaglandins in regulating tubular function.