抄録
Vanadate is known to have various insulin-like actions including activation of D-glucose uptake into the skeletal muscle and adipose tissue. In this study, we examined the effect of orthovanadate on D-glucose uptake into sarcolemmal vesicles prepared from rat hind limb skeletal muscles. In the presence of 10mM vanadate, the initial rate of D-glucose uptake into sarcolemmal vesicles was enhanced 4-5 times above the basal value. Half-maximal concentration for this effect of vanadate was 3mM. The n-glucose uptake was also stimulated by metavanadate, but not by selenite, selenate, or molybdate. When vanadate was removed from the vesicles by dilution and centrifugation, n-glucose uptake into the vesicles returned to the basal level, indicating that the effect of vanadate was reversible. Saturation curves showed that the Vmax value for the n-glucose uptake was enhanced more than 4-fold by 10mM vanadate. Therefore, the activation of D-glucose uptake was due, at least in part, to a large increase in the Vmax value. These results suggest that vanadate increases the intrinsic activity (turnover number) of skeletal muscle glucose transporters in a reversible manner.
