Effects of penicillin pretreatment on renal tubular para-aminohippurate transport in the immature rat.

The effect of pretreatment with penicillin on para-aminohippurate (PAH) transport by the kidney of the immature rat was evaluated in vivo. After 3 days of penicillin administration, renal clearances of inulin (CIN), PAH (CPAH), and the renal tubular transport maximum (Tm) for PAH were measured in rats as young as 17 days of age. The CPAH in 19- to 21-day-old rats pretreated with procaine penicillin was 54% greater than that of their littermate controls. Similarly, CPAH of rats that received sodium penicillin was 31% greater than control. CIN was not increased after penicillin pretreatment. Pretreatment of rats older than 24 days did not change CIN or CPAH. The Tm for PAH of 17-day-old rats pretreated with sodium penicillin was 51% greater than that of control rats. It was concluded that pretreatment with penicillin enhances the renal secretion of organic anions by the immature rat.