Stimulation of Insulin-dependent Glucose Transport and Lipogenesis in Isolated Rat Adipocytes by Trypsinized Soybean Glycinin Acidic Subunit A1a

1994 ◽  
Vol 58 (3) ◽  
pp. 590-591 ◽  
Author(s):  
Yuji Ishikawa ◽  
Chino Kumagai ◽  
Ryuichi Moriyama ◽  
Shio Makino
Keyword(s):  
Glucose Transport ◽  
Rat Adipocytes ◽  
Insulin Dependent ◽  
Isolated Rat ◽  
Stimulation Of ◽  
Acidic Subunit

scholarly journals Catecholamine-induced insulin resistance of glucose transport in isolated rat adipocytes

1983 ◽  
Vol 216 (3) ◽  
pp. 737-745 ◽  
Author(s):  
D M Kirsch ◽  
M Baumgarten ◽  
T Deufel ◽  
F Rinninger ◽  
W Kemmler ◽  
...  
Keyword(s):  
Glucose Transport ◽  
Insulin Binding ◽  
Affinity Binding ◽  
Insulin Stimulation ◽  
High Affinity Binding ◽  
Rat Adipocytes ◽  
High Affinity ◽  
Atp Levels ◽  
Isolated Rat ◽  
Stimulation Of

The effects of pre-incubation with isoprenaline and noradrenaline on insulin binding and insulin stimulation of D-glucose transport in isolated rat adipocytes are reported. (1) Pre-incubation of the cells with isoprenaline (0.1-10 microM) in Krebs-Ringer-Hepes [4-(2-hydroxyethyl)-1-piperazine-ethanesulphonic acid] buffer (30 min, 37 degrees C) at D-glucose concentrations of 16 mM, in which normal ATP levels were maintained, caused a rightward-shift in sensitivity of D-glucose transport to insulin stimulation by 50% and a decrease in maximal responsiveness by 30% (2) [A14-125I]insulin binding was reduced significantly by 35% at insulin concentrations less than 100 mu-units/ml and Scatchard analysis showed that this consisted mainly of a decrease in high-affinity binding. (3) Pre-incubation with catecholamines under the same conditions but at low glucose concentrations (0-5 mM) caused a fall in intracellular ATP levels of 65 and 45% respectively. (4) The fall in ATP additionally lowered insulin binding by 50% at all insulin concentrations and a parallel shift of the binding curves in the Scatchard plot showed that this was due to a decrease in the number of receptors. (5) At low and high ATP concentrations the insulin stimulation of D-glucose transport was inhibited to a similar extent. (6) Pre-incubation with catecholamines thus inhibited insulin stimulation of D-glucose transport in rat adipocytes mainly by a decrease in high-affinity binding of insulin, which was not mediated by low ATP levels. This mechanism may play a role in the pathogenesis of catecholamine-induced insulin resistance in vivo.

Immunoelectron microscopic evidence that GLUT4 translocation explains the stimulation of glucose transport in isolated rat white adipose cells

2000 ◽  
Vol 113 (23) ◽  
pp. 4203-4210 ◽  
Author(s):  
D. Malide ◽  
G. Ramm ◽  
S.W. Cushman ◽  
J.W. Slot
Keyword(s):  
Adipose Tissue ◽  
Glucose Transport ◽  
Morphological Evidence ◽  
Glut4 Translocation ◽  
Transport Activity ◽  
Brown Adipose ◽  
Quantitative Immunoelectron Microscopy ◽  
Adipose Cells ◽  
Isolated Rat ◽  
Stimulation Of

We used an improved cryosectioning technique in combination with quantitative immunoelectron microscopy to study GLUT4 compartments in isolated rat white adipose cells. We provide clear evidence that in unstimulated cells most of the GLUT4 localizes intracellularly to tubulovesicular structures clustered near small stacks of Golgi and endosomes, or scattered throughout the cytoplasm. This localization is entirely consistent with that originally described in brown adipose tissue, strongly suggesting that the GLUT4 compartments in white and brown adipose cells are morphologically similar. Furthermore, insulin induces parallel increases (with similar magnitudes) in glucose transport activity, approximately 16-fold, and cell-surface GLUT4, approximately 12-fold. Concomitantly, insulin decreases GLUT4 equally from all intracellular locations, in agreement with the concept that the entire cellular GLUT4 pool contributes to insulin-stimulated exocytosis. In the insulin-stimulated state, GLUT4 molecules are not randomly distributed on the plasma membrane, but neither are they enriched in caveolae. Importantly, the total number of GLUT4 C-terminal epitopes detected by the immuno-gold method is not significantly different between basal and insulin-stimulated cells, thus arguing directly against a reported insulin-induced unmasking effect. These results provide strong morphological evidence (1) that GLUT4 compartments are similar in all insulin-sensitive cells and (2) for the concept that GLUT4 translocation almost fully accounts for the increase in glucose transport in response to insulin.

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.

Insulin induces Ca2+ influx into isolated rat hepatocyte couplets

1997 ◽  
Vol 272 (6) ◽  
pp. G1425-G1432 ◽  
Author(s):  
K. Benzeroual ◽  
G. van de Werve ◽  
S. Meloche ◽  
L. Mathe ◽  
A. Romanelli ◽  
...  
Keyword(s):  
Peptide Hormone ◽  
Insulin Binding ◽  
Mitogen Activated Protein Kinase ◽  
Rat Hepatocyte ◽  
Mapk Activity ◽  
Mitogen Activated Protein ◽  
Insulin Dependent ◽  
Dose Dependent Increase ◽  
Isolated Rat ◽  
Stimulation Of

Isolated rat hepatocyte couplets were used to study the direct effect of insulin on intracellular Ca2+ homeostasis. Insulin induced a dose-dependent increase in hepatocellular Ca2+ that was gradual, generally monophasic, and reversible. Chelation of extracellular Ca2+ abolished the insulin-induced Ca2+ response, and this suppression was not related to an effect on insulin binding, as indicated by displacement studies. We thus tested the effect of several Ca2+ channel inhibitors on insulin-induced Ca2+ influx. Verapamil at 20 or 200 microM was without effect, whereas 500 microM nickel and 50 microM gadolinium strongly inhibited insulin-induced Ca2+ entry. Finally, we tested whether insulin-induced Ca2+ movements were implicated in the stimulation of mitogen-activated protein kinase (MAPK) activity, which we measured with the use of an immune-complex assay. Verapamil was without effect on the insulin-dependent stimulation of p44mapk activity, whereas addition of ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid, nickel, or gadolinium strongly inhibited the effect of the peptide hormone. Our results indicate that insulin triggers Ca2+ influx into hepatocytes, possibly through the opening of channels on the plasma membrane, and that this effect is important for insulin activation of MAPK.

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