Hexose transport stimulation and membrane redistribution of glucose transporter isoforms in response to cholera toxin, dibutyryl cyclic AMP, and insulin in 3T3-L1 adipocytes.

摘要: Exposure of 3T3-L1 adipocytes to 100 ng/ml cholera toxin or 1 mM dibutyryl cyclic AMP caused a marked stimulation deoxyglucose transport. A maximal increase 10- 15-fold was observed after 12-24 h exposure, while nM insulin elicited an similar magnitude within 30 min. short term exposure (4 h) cells resulted in 3- 4-fold transport which associated with significant redistribution both the HepG2/erythrocyte (GLUT1) and muscle/adipocyte (GLUT4) glucose transporters from low density microsomes plasma membrane fraction. Total cellular amounts transporter proteins remained constant. In contrast, exposed for 12 exhibited elevations total contents GLUT1 (but not GLUT4) protein about 1.5- 2.5-fold above controls, respectively. Although such treatments (12 versus (30 min) 10-fold enhancements transport, striking discrepancy respect content While 2.6-fold levels GLUT4 fraction, increased amount this by only 30%. Insulin fraction equally (1.6-fold). Thus, greater number is compared toxin. We conclude that: 1) at early times addition adipocytes, appears contribute elevated uptake rates, 2) hexose prolonged treatment (12-18 may involve additional intrinsic activity one isoforms.