[Concentration of p-aminohippuric acid in the serum and kidney tissue during stimulation of renal excretion of foreign materials].

The renal excretion of p-aminohippuric acid (PAH) can be stimulated in adult rats by repeated applications of probenecid, cyclopenthiazide, and phenobarbital. The present studies have shown that this pretreatment significantly shortens the half-life for PAH too. In pretreated animals the PAH concentration decreases in the renal tissue more rapidly than in the control animals. These results were obtained in adult animals only but not in 5-day-old rats, in which the pretreatment had no effect upon the rate of renal PAH excretion. The pretreatment did not change the renal weight of 5-and 55-day-old rats.