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.

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

scholarly journals Modification of the 85-kilodalton subunit of phosphatidylinositol-3 kinase in platelet-derived growth factor-stimulated cells.

1992 ◽  
Vol 12 (8) ◽  
pp. 3415-3424 ◽  
Author(s):  
W M Kavanaugh ◽  
A Klippel ◽  
J A Escobedo ◽  
L T Williams
Keyword(s):  
Tyrosine Phosphorylation ◽  
Platelet Derived Growth Factor ◽  
Affinity Binding ◽  
Pdgf Receptor ◽  
Phosphatidylinositol 3 Kinase ◽  
High Affinity Binding ◽  
High Affinity ◽  
Pdgf Stimulation ◽  
Stimulation Of

The activated platelet-derived growth factor (PDGF) receptor physically associates with p85, a subunit of phosphatidylinositol-3 kinase. Although this interaction may activate phosphatidylinositol-kinase and is crucial for PDGF-induced mitogenesis, it has not been shown whether p85 is modified in the process. p85 contains two SH2 (Src homology) domains, designated SH2-N and SH2-C. Recent experiments have shown that the SH2-C domain alone determines high-affinity binding of p85 to the PDGF receptor. The function of SH2-N, which binds receptors with lower affinity, is unknown. In this study, using a receptor-blotting technique, we find that p85 is modified by PDGF stimulation of intact cells. This modification involves inhibition of binding of the SH2-N region of p85 to the PDGF receptor. Studies with vanadate suggest that tyrosine phosphorylation of p85 is responsible for the modification of p85 detected by receptor blotting. Furthermore, recombinant p85 is modified in a similar manner when it is tyrosine phosphorylated in vitro by PDGF receptors. Tyrosine phosphorylation of p85 does not block binding of the SH2-C domain and therefore does not release p85 from high-affinity binding sites on the receptor in vitro. Instead, phosphorylation may regulate the ability of the SH2-N of p85 to bind to a different portion of the PDGF receptor or to another molecule in the signaling complex. This study provides the first evidence that p85 is tyrosine phosphorylated upon PDGF stimulation of cells and suggests that tyrosine phosphorylation of p85 regulates its activity or its interaction with other proteins.

Regulatory effect of cholecystokinin on subsequent insulin binding to pancreatic acini

1990 ◽  
Vol 258 (4) ◽  
pp. E562-E568
Author(s):  
Y. Okabayashi ◽  
M. Otsuki ◽  
T. Nakamura ◽  
M. Koide ◽  
H. Hasegawa ◽  
...  
Keyword(s):  
Binding Site ◽  
Insulin Binding ◽  
Pancreatic Acinar Cells ◽  
Affinity Binding ◽  
Regulatory Effect ◽  
Pancreatic Acini ◽  
High Affinity Binding ◽  
Receptor Affinity ◽  
High Affinity ◽  
High Affinity Binding Site

We investigated the regulatory effect of cholecystokinin (CCK) on subsequent insulin binding to pancreatic acinar cells. Rat isolated acini were preincubated with various concentrations of CCK octapeptide (CCK-8) at 37 degrees C. Acini were then washed, resuspended in the binding buffer, and incubated with 8.3 pM 125I-labeled insulin for 60 min at 37 degrees C. Pretreatment with CCK-8 caused inhibition of subsequent 125I-insulin binding that was time and concentration dependent. Significant inhibition was observed with 3 pM CCK-8. Computer analysis of the competition-inhibition study with a nonlinear least-squares curve-fitting program revealed that CCK-8 pretreatment of acini reduced the receptor affinity of the high-affinity binding site. This inhibitory action of CCK-8 was not due to the alteration in degradation or internalization of the tracer. When acini were pretreated with 100 pM CCK-8 for 120 min at 4 degrees C, a reduction in the receptor affinity of the high-affinity binding site was also observed. In pancreatic membrane prepared from acini preincubated with 100 pM CCK-8 for 120 min at 37 degrees C, displacement of 125I-insulin (83 pM) by unlabeled insulin (24 degrees C, 1 h) revealed that CCK-8 inhibited 125I-insulin binding by altering the receptor affinity of the high-affinity binding site. In acinar preparations the inhibitory effect of CCK-8 on 125I-insulin binding was abolished when acini were preincubated with CCK-8 and CCK receptor antagonist L 374718 at 37 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)

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