KINETICS OF THE CO-TRANSPORT OF PHENYLALANINE AND SODIUM IONS IN THE GUINEA-PIG SMALL-INTESTINE .1. PHENYLALANINE FLUXES

  • 1 January 1978
    • journal article
    • research article
    • Vol. 74  (6) , 569-574
Abstract
The kinetics of phenylalanine influx into guinea-pig small intestinal rings at different external Na concentrations were examined. A change in the Na concentration alters the value of Kt [transport constant] for phenylalanine influx without affecting the Vmax for the process. By studying the relationship between the value of Kt and the Na concentration, the applicability of various models to the overall process of Na-coupled phenylalanine influx has been considered. A ternary complex may form between carrier, phenylalanine molecule and a Na ion, which can be formed from either binary complex, i.e., either species can combine 1st to the carrier. The consistency of this model was tested by determining phenylalanine influx as a function of the Na concentration at different amino acid concentrations, and a good fit was obtained with the predictions of this model.