The effect of saline-induced extracellular volume expansion on the kidney function

Indomethacin and diclofenac sodium increase sodium and water excretion after extracellular volume expansion in the rabbit

The renal effects of an acute extracellular fluid volume expansion (50 ml Ringer/kg body weight/60 min) were studied in aldosterone-treated (100 microgram/kg), anesthetized rabbits with and without pretreatment with either indomethacin (3.0 mg/kg) or diclofenac sodium (3.0 mg/kg), two different inhibitors of renal prostaglandin (PG) biosynthesis. In controls (n = 7), the volume expansion increased urine flow from 1.5 +/- 0.24 to 6.1 +/- 0.5 (S.E.) ml/min/100 g kidney weight and sodium excretion from 0.15 +/- 0.03 to 0.99 +/- 0.10 mmol/min/100 g. PAH and inulin clearance increased by 42 and 58%, respectively, while plasma renin activity and urinary excretion of PGF2 alpha-like immunoreactivity were reduced (P less than 0.05). In animals pretreated with indomethacin (n = 6) or diclofenac sodium (n = 6), the diuresis and the natriuresis following volume expansion were significantly increased about two-fold over controls, whereas PAH and inulin clearance, plasma renin activity and hematocrit did not differ from controls. Both drugs were found to reduce urinary excretion of PGF2 alpha-like immunoreactivity by 75--95% througout the experiment. The results indicate that diclofenac sodium, indomethacin and extracellular volume expansion enhance sodium and water excretion partly by suppression of a PG sensitive reabsorption process in the kidney.

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.