Carrier-mediated transport of cephalexin via the dipeptide transport system in rat renal brush-border membrane vesicles.

Carrier-mediated transport of aminocephalosporin antibiotics by renal brush-border membrane vesicles has been studied in relation to the transport systems for dipeptides and amino acids. Dipeptides such as L-carnosine (beta-alanyl-L-histidine) and L-phenylalanylglycine competitively inhibited the uptake of cephalexin, but amino acids did not. Cephalexin uptake was stimulated by the countertransport effect of L-carnosine in the normal and papain-treated vesicles, and by the effect of L-phenylalanylglycine only in the papain-treated vesicles. In the papain-treated vesicles, the hydrolysis of dipeptides was markedly decreased, and the specific activity for cephalexin transport was increased approx. 2-fold because of the partial removal of membrane proteins. These results suggest that carrier-mediated transport of cephalexin can be transported by the system for dipeptides in renal brush-border membranes.