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 kidney of the immature rat was evaluated in vivo. After 3 days of penicillin administration, the renal clearances of inulin (CIN), PAH(CPAH), and N-methylnicotinamide (CNMN) and the rental tubular transport maximum (Tm) for PAH were measured in rats as young as 17 days of age. The CPAH by 19- to 21-day old rats pretreated with procaine penicillin was 46% greater than that of there litter-mate controls. Similarly, CPAH of rats that received sodium penicillin was 27% greater than control. CIN was not increased after penicillin pretreatment. Pretreatment with penicillin of rats older than 24 days of age 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. Sodium penicillin-pretreated rats had a lower CNMN that did control rats. These results are in contrast with the normal pattern of renal maturation in which CIN, CPAH, and PAH Tm all increase with age. It was concluded that pretreatment with penicillin stimulates the renal secretion of organic anions by the immature rat.