Cytoplasmic Ca2+ inhibits the glucose transporter of human erythrocytes.

The effect of Ca2+ on the glucose transporter of human erythrocytes was investigated. The results showed that extracellular Ca2+ had no effect. But, the glucose transport of erythrocytes was markedly inhibited due to the increase in cytoplasmic Ca2+ concentration by addition of ionophore A23187. The Ca2+ inhibition exhibited a dose-dependent manner with an apparent half maximal concentration of 250 microM and could not be recovered by 10 mM EGTA. Unlike Ca2+, Mg2+ did not affect the glucose transporter.