Translocation of glucose transporters in response to anoxia in heart.

We tested whether translocation of glucose transporters between subcellular membrane fractions is involved in the stimulation of glucose transport by anoxia by perfusing rat hearts in the presence or absence of oxygen. The hearts were then fractionated by a modification of the procedures of Watanabe, et al. (Watanabe, T., Smith, M. M., Robinson, F. W., and Kono, T. (1984) J. Biol. Chem. 259, 13117-13122), who previously demonstrated translocation in response to insulin in heart, to give plasma membrane and high-speed pellet fractions. The contents of glucose transporters in the two fractions were determined by reconstitution of transport activity, D-glucose-reversible binding of cytochalasin B, and labeling with antibodies against the erythrocyte transporter. The heart transporter was also recognized by antibodies against the COOH-terminal peptide of the glucose transporter. All three types of assays revealed a decrease (20-30%) in the high-speed pellet fraction and an increase (20-70%) in the plasma membranes in response to anoxia. Treatment of hearts with insulin produced a similar extent of translocation and a similar stimulation (about 2-fold) of glucose uptake, indicating that translocation plays a role of similar importance in the stimulation of transport by both of these effectors.