Nucleoside transport in human erythrocytes. A simple carrier with directional symmetry in fresh cells, but with directional asymmetry in cells from outdated blood

Abstract

Kinetic characteristics of the transport of uridine, a nonmetabolized permeant in human erythrocytes, were compared in erythrocytes from fresh and outdated stored blood. Uridine transport kinetics in fresh cells conformed to the predictions of a simple carrier model operating with directional symmetry, but in erythrocytes from outdated blood the kinetic characteristics of uridine transport were those of an asymmetric system. The latter result agrees with earlier reports by others. The mobility of the loaded and empty carriers differed by about 6- and 12-fold in fresh and outdated blood, respectively.