Effects of 4-pentenoic acid and furosemide on renal functions and renal uptake of individual free fatty acids.

1. Effects of 4-pentenoic acid (4-PA), an inhibitor of fatty acid oxidation, on renal fatty acids (FFA) were investigated using mongrel dogs, and the results compared with findings in the case of furosemide. 2. Continuous infusion of 4-PA at a rate of 0.66 mumoles/kg.min into the renal artery resulted in a marked reduction of glomerular filtration rate after 45 min. Sodium reabsorption rate tended to decrease at 30 min and a significant decrease was seen after 45 min. With decrease in the renal sodium reabsorption rate, the urine flow increased about 3 times, and there was a marked natriuresis. 3. Concentrations of individual FFA in the arterial and renal venous plasma were determined by gas-liquid chromatographic analysis. In the control period, data from 25 dogs showed renal uptake of palmitic, stearic, oleic, and linoleic acids to be approximately 40, 15, 25, and 10 nmoles/g.min, respectively, and the uptake of palmitic and oleic acids was depressed during the natriuresis following administration of 4-PA and furosemide. 4. These results suggest that fatty acids play an important role in the energy supply in renal tubular sodium transport.