Kinetics of Na+-dependent D-glucose transport

✍ Scribed by Hopfer, Ulrich

• Book ID: 102926499
• Publisher: Wiley (John Wiley & Sons)
• Year: 1977
• Tongue: English
• Weight: 704 KB
• Volume: 7
• Category: Article
• ISSN: 0091-7419
• DOI: 10.1002/jss.400070102

✦ Synopsis

The kinetic parameters of the Na+-dependent glucose transport system have been determined in isolated membrane vesicles for D-glucose, Na+, and phlorhizin. The D-glucose flux measurements were carried out by the equilibrium exchange procedure at constant external and internal Na+ concentrations and zero potential. Equations were developed to extract information about K, and Vmax from uptake measurements into a vesicle population that is heterogeneous with respect to size (surface to volume ratio). The K, for D-glucose was 14 mM and independent of the Na+concentration, while the V,,, was strongly Na+-dependent and increased I 5-fold between 1 and 100 mM Na+. The K, of Na+ for activation of the V,, was 18 mM. The calculated K1 values for phlorhizin were 2.7 and 1.9 pM when determined under active and equilibrating D-glucose flux conditions, respectively.