Dibasic aminod acid transport in rat-kidney cortex slices

Abstract

The effect of anaerobiosis, Na + deprivation and pH alteration on the accumulation of l-lysine, l-arginine, l-diaminobutyric acid and l-cystine was studied at physiological levels of substrate in rat-kidney cortex slices. Lysine, arginine and diaminobutyric acid were capable of being actively transported despite oxygen and Na + lack in the incubation medium. Initial rates of accumulation of lysine and diaminobutyric acid appeared to be normal under the latter conditions although the steady-state concentration gradients were reduced. Cystine and arginine transport was inhibited initially and there was impairment of the ability to form a concentration gradient, most marked for cystine in Na +-free medium. The variation of accumulation with pH differed for each of the amino acids, the curve of cystine being more like that of glycine, than the dibasic amino acids. The results lend further support to the concept that cystine transport in kidney slices occurs by a system separate from that of dibasic amino acids and indicate that for the other dibasic amino acids, variation of intra-group transport characteristics is present.