EFFECTS OF CALCIUM ON BRAZILIN-INDUCED GLUCOSE-TRANSPORT IN ISOLATED RAT EPIDIDYMAL ADIPOCYTES

Brazilin increased [H-3]2-deoxyslucose uptake in isolated rat epididym al adipocytes. The fact that calcium may be required for the stimulato ry effects of insulin on glucose transport suggests that brazilin migh t also require calcium for its glucose transport-stimulating action. C hanges in the concentration of extracellular calcium had no significan t effect on brazilin-induced glucose transport. Nifedipine and verapam il decreased brazilin-induced glucose transport, and quin2-AM abolishe d the effect of brazilin on glucose transport. A23187, however, showed no effect on brazilin action. Ca-45(2+) uptake into adipocytes was no t influenced by brazilin treatment, and trifluoperazine significantly inhibited the effect of brazilin an glucose transport. These data sugg est that calmodulin and the maintenance of the intracellular calcium c oncentration, rather than an increase in it, may be essential for the stimulatory action of brazilin on glucose transport. (C) 1997 Elsevier Science Inc.