Amino-acid Transport in Hamster Small Intestine: Site of Inhibition by D-Galactose

Abstract

TRANSPORT of sugars and amino-acids in the small intestine occurs by apparently similar Na⁺-activated mechanisms which are believed to involve reversible binding of substrate to specific membrane receptors or carriers (for review, see ref. 1). At some level of the transport process, interactions between sugars and amino-acids are known to occur as indicated by reciprocal inhibitory effects^2–10. Various hypotheses have been advanced to explain these findings, but the observations from several different laboratories—taken collectively—seem contradictory to the point of making each of these hypotheses untenable. The purpose of this communication is to re-examine the problem in the light of some new observations with hamster intestine and, using this information, to ascertain whether the lack of agreement between various laboratories may simply be a result of a failure to take into consideration the existence of significant differences between species.