Transport of amino acids in ehrlich ascites cells: Competitive stimulation

Abstract

1. 1. The term `competitive stimulation' refers to an experimental finding in which the uptake of one amino acid is increased in the presence of another amino acid when both are initially present extracellularly. The uptake of both amino acids of such pairs was investigated with use of double-label techniques.2. 2. For all amino acid pairs examined which showed competitive stimulation, the uptake of one amino acid was increased whereas that of the other was decreased. Furthermore, the decrease in uptake of the latter was considerably greater than the increase in uptake of the former.3. 3. In time studies it was found that the distribution ratio of the amino acid whose uptake was stimulated was increased at all incubation times up to 30 min. The amino acid whose uptake was inhibited showed not only a markedly decreased uptake but also a significantly altered curve of time dependent of uptake.