Metabolic studies on renal transport of p-aminohippurate in vitro

Abstract

1. 1. Slices of rabbit-kidney cortex were incubated in an oxygenated electrolyte medium, and their accumulation of p-aminohippurate, O 2 consumption ( Q O 2 ) and production of 14CO 2 from d-[6- 14C]glucose or [ I- 14C]palmitate were measured in the presence and absence of various metabolic inhibitors. 2. 2. A pronounced inhibition of accumulation of p-aminohippurate, relative to that of Q O 2 and liberation of 14CO 2 from the labelled coumpounds, was observed in the case of fluoroacetate and malonate. 3. 3. F − caused a marked reduction of accumulation of p-aminohippurate, and the results suggest that the accompanying decrease of Q O 2 was due to an inhibitiion of d-glucose oxidation exclusively. Accumulation of p-aminohippurate was inhibited by 2-deoxy- d-glucose although no effect on glycolysis and on oxidative processes could be detected. 4. 4. Pyruvate efficiently counteracted the inhibitory effect of the above-mentioned metabolic inhibitors on accumulation of p-aminohippurate, whereas l-lactate and acetate reversed accumulation of p-aminohippurate to a variable extent. d-Glucose only stimulated accumulation of p-aminohippurate in the presence of 2-deoxy- d-glucose. 5. 5. The results indicate that the active transport of p-aminohippurate is very sensitive to a decrease of oxidative energy metabolism. The experiments suggest that at low concentrations the metabolic inhibitors do not interact directly with the transport system. It is concluded that metabolism of substances connected with carbohydrate metabolism, probably pyruvate and l-lactate, is necessary for active transport of p-aminohippurate to occur.