Regulation of glucose transport in isolated adipocytes by levamisole

1992 ◽  
Vol 70 (8) ◽  
pp. 1190-1194 ◽  
Author(s):  
Nirmal S. Basi ◽  
K. G. Thomaskutty ◽  
Richard H. Pointer
Keyword(s):  
Glucose Transport ◽  
Glucose Oxidation ◽  
Glucose Utilization ◽  
Rat Adipocytes ◽  
Phosphofructokinase Activity ◽  
Isolated Adipocytes ◽  
Isolated Rat

When isolated rat adipocytes were incubated with increasing concentrations of levamisole (0.5–5 mM), basal glucose oxidation decreased by almost 50% and insulin-stimulated glucose oxidation decreased by 90%. The decrease in glucose oxidation correlated with an inhibition of glucose transport, since levamisole at 5.0 mM decreased basal 3-O-methylglucose transport by 60% and insulin-stimulated transport by 80%. Diamide-stimulated glucose transport was also inhibited approximately 80% by 5.0 mM levamisole. Levamisole at concentrations up to 5.0 mM had no effect on phosphofructokinase activity. The present results suggest that levamisole inhibits glucose utilization by inhibiting glucose transport in a concentration-dependent manner.Key words: insulin, levamisole, glucose transport, adipocytes.

scholarly journals Insulin-like effects of dithiothreitol on isolated rat adipocytes

1981 ◽  
Vol 200 (2) ◽  
pp. 425-428 ◽  
Author(s):  
H Goko ◽  
S Takashima ◽  
A Kawamuro ◽  
A Matsuoka
Keyword(s):  
Glucose Oxidation ◽  
Insulin Receptors ◽  
Insulin Binding ◽  
Dibutyryl Cyclic Amp ◽  
Rat Adipocytes ◽  
Adrenergic Antagonist ◽  
Isolated Adipocytes ◽  
Dose Dependent ◽  
Isolated Rat ◽  
Stimulation Of

The effects of dithiothreitol on basal glucose oxidation, hormone-induced lipolysis and insulin receptors in isolated rat adipocytes were studied. Dithiothreitol produced a dose-dependent stimulation of basal glucose oxidation and inhibition of adrenaline-induced lipolysis. Dithiothreitol also inhibited corticotropin-induced lipolysis, but failed to inhibit dibutyryl cyclic AMP-induced lipolysis. Dithiothreitol did not inhibit the binding of the beta-adrenergic antagonist [3H]dihydroalprenolol to adipocytes. Neither catalase (100 micrograms/ml) nor EDTA (2 mM) abolished the antilipolytic effect of dithiothreitol. Treatment of isolated adipocytes with 1 mM-dithiothreitol for 20 min at 37 degrees C also caused stimulation of basal glucose oxidation and inhibition of adrenaline-induced lipolysis. A Scatchard plot of insulin binding to control adipocytes was curvilinear. However, treatment of cells with 1 mM-dithiothreitol decreased the curvilinearity of the plot, indicating that only a low-affinity state of the insulin receptors exists in the dithiothreitol-treated adipocytes. These findings suggest that the insulin-like activities of dithiothreitol are mediated through the interaction of dithiothreitol with insulin receptors.

Effect of purified phospholipases on glucose transport, insulin binding, and insulin action in isolated rat adipocytes

1982 ◽  
Vol 4 (4) ◽  
pp. 261-271 ◽  
Author(s):  
Tj. Wieringa ◽  
G. Bruin ◽  
W. P. M. Meerwijk ◽  
H. M. J. Krans
Keyword(s):  
Glucose Transport ◽  
Insulin Action ◽  
Insulin Binding ◽  
Rat Adipocytes ◽  
Isolated Rat

Glucose transport in isolated rat adipocytes with measurements of L-arabinose uptake.

1978 ◽  
Vol 234 (2) ◽  
pp. E112 ◽  
Author(s):  
J E Foley ◽  
S W Cushman ◽  
L B Salans
Keyword(s):  
Glucose Transport ◽  
Transport System ◽  
Cytochalasin B ◽  
Competitive Inhibition ◽  
Facilitated Transport ◽  
Time Dependent ◽  
Rat Adipocytes ◽  
A Value ◽  
System Data ◽  
Isolated Rat

Data is presented suggesting that rates of L-arabinose transport, calculated from L-[1-14C]arabinose uptake measurements, can be used as indicators of changes in the rates of glucose transport in isolated rat adipocytes. L-[1-14C]arabinose, at 37 degrees C, was found to be nonmetabolizable and taken up by adipocytes exponentially with time reaching 95% of equilibrium in 30 min. When L-arabinose is corrected for background, the corrected uptake values conform to the time-dependent monoexponential uptake relationshiop predicted for a facilitated transport system and are not significantly different from 0 in the presence of 70 micron cytochalasin B. Transport rates were calculated from corrected uptake values near the half-maximal uptake of L-arabinose and from a value of the total amount of L-arabinose in the cell at equilibrium. Competitive inhibition of L-arabinose transport by glucose and countertransport of L-arabinose in the presence of glucose suggest that L-arabinose and glucose share the same transport system. Data is presented demonstrating the effect of insulin and dexamethasone on the transport system that confirms the conclusions obtained by other investigators using other methods.

scholarly journals Proteolytic cleavage of cellubrevin and vesicle-associated membrane protein (VAMP) by tetanus toxin does not impair insulin-stimulated glucose transport or GLUT4 translocation in rat adipocytes

1997 ◽  
Vol 321 (1) ◽  
pp. 233-238 ◽  
Author(s):  
Eric HAJDUCH ◽  
J. Carlos ALEDO ◽  
Colin WATTS ◽  
Harinder S. HUNDAL
Keyword(s):  
Plasma Membrane ◽  
Membrane Protein ◽  
Glucose Uptake ◽  
Glucose Transport ◽  
Tetanus Toxin ◽  
Glucose Transporter ◽  
Detectable Effect ◽  
Glut4 Translocation ◽  
Rat Adipocytes ◽  
Isolated Rat

Acute insulin stimulation of glucose transport in fat and skeletal muscle occurs principally as a result of the hormonal induced translocation of the GLUT4 glucose transporter from intracellular vesicular stores to the plasma membrane. The precise mechanisms governing the fusion of GLUT4 vesicles with the plasma membrane are very poorly understood at present but may share some similarities with synaptic vesicle fusion, as vesicle-associated membrane protein (VAMP) and cellubrevin, two proteins implicated in the process of membrane fusion, are resident in GLUT4-containing vesicles isolated from rat and murine 3T3-L1 adipocytes respectively. In this study we show that proteolysis of both cellubrevin and VAMP, induced by electroporation of isolated rat adipocytes with tetanus toxin, does not impair insulin-stimulated glucose transport or GLUT4 translocation. The hormone was found to stimulate glucose uptake by approx. 16-fold in freshly isolated rat adipocytes. After a single electroporating pulse, the ability of insulin to activate glucose uptake was lowered, but the observed stimulation was nevertheless nearly 5-fold higher than the basal rate of glucose uptake. Electroporation of adipocytes with 600 nM tetanus toxin resulted in a complete loss of both cellubrevin and VAMP expression within 60 min. However, toxin-mediated proteolysis of both these proteins had no effect on the ability of insulin to stimulate glucose transport which was elevated approx. 5-fold, an activation of comparable magnitude to that observed in cells electroporated without tetanus toxin. The lack of any significant change in insulin-stimulated glucose transport was consistent with the finding that toxin-mediated proteolysis of both cellubrevin and VAMP had no detectable effect on insulin-induced translocation of GLUT4 in adipocytes. Our findings indicate that, although cellubrevin and VAMP are resident proteins in adipocyte GLUT4-containing vesicles, they are not required for the acute insulin-induced delivery of GLUT4 to the plasma membrane.

Sign in / Sign up

Export Citation Format

Share Document