Beta-adrenergic receptors are not responsible for exercise stimulation of glucose transport

1989 ◽  
Vol 66 (5) ◽  
pp. 2419-2422 ◽  
Author(s):  
E. Sternlicht ◽  
R. J. Barnard ◽  
G. K. Grimditch
Keyword(s):  
Glucose Transport ◽  
Binding Sites ◽  
Adrenergic Receptor ◽  
Acute Exercise ◽  
Exercise Bout ◽  
Exercise Session ◽  
Beta Adrenergic Receptor ◽  
Beta Adrenergic ◽  
Number Of Binding Sites ◽  
Dissociation Constant Kd

This study was designed to examine whether the increased glucose transport after acute exercise in rat skeletal muscle is mediated via beta-adrenergic receptor stimulation. Sarcolemmal (SL) membranes were isolated from three groups: control (C), acute exercise (E), and exercise + propranolol (E+P). The acute exercise bout was performed on a treadmill and consisted of a 45-min run until near exhaustion. E+P received an intravenous propranolol injection (0.8 mg/kg) 10 min before the exercise session. Michaelis-Menten kinetics at 1.5 s indicated that the Vmax for glucose transport was increased after each perturbation compared with C but were not different from each other (E, 4,334 +/- 377; E+P, 4,824 +/- 357; and C, 1,366 +/- 124 pmol.mg protein-1.s-1). The apparent Km's were similar in all groups. Scatchard plots for the D-glucose inhibitable class of cytochalasin B binding sites indicated no differences in either the total number of binding sites in the SL vesicles (C, 5.5 +/- 0.3; E, 5.1 +/- 0.2, and E+P, 5.1 +/- 0.3 pmol/mg protein) or in their dissociation constant (Kd) (C, 46 +/- 3; E, 48 +/- 3; and E+P, 49 +/- 2 nM). The increase in Vmax for transport was similar between E and E+P, indicating that exercise does not stimulate glucose transport via the beta-adrenergic receptor.

Effect of training on beta-adrenergic receptor number in rat heart

1982 ◽  
Vol 52 (5) ◽  
pp. 1133-1137 ◽  
Author(s):  
R. L. Moore ◽  
M. Riedy ◽  
P. D. Gollnick
Keyword(s):  
Endurance Training ◽  
Binding Sites ◽  
Adrenergic Receptor ◽  
Sprague Dawley ◽  
Beta Adrenergic Receptor ◽  
Beta Adrenergic ◽  
Binding Characteristics ◽  
Crude Homogenate ◽  
Plot Analysis ◽  
Receptor Number

Female Sprague-Dawley rats were subjected to endurance-training programs, and the effect of training on myocardial beta-adrenergic receptor number, receptor-binding characteristics, and adenylate cyclase (AC) activities associated with the receptor were examined. Training produced a 45% (P less than 0.01) increase in the succinate dehydrogenase activity of the plantaris muscle. Specific (-)-[3H]dihydroalprenolol (DHA)-binding data were subjected to Scatchard plot analysis to quantify beta-adrenergic receptor number and DHA-binding characteristics of myocardial membranes. The DHA concentrations at which 50% of the total binding sites were occupied were similar for membranes from sedentary (1.95 +/- 0.51) and trained (1.59 +/- 0.34 nM) groups. Total DHA-binding sites of membranes from control (91.6 +/- 13.3) and trained (83.1 +/- 7.6 fmol/mg) groups were also similar. Basal and maximally stimulated AC activities were also unchanged by endurance training. Fluoride-stimulated AC activities of crude homogenate and 10,000 g fractions decreased 47 and 49%, respectively, with training. No differences were observed in a 40,000 g fraction. The specific activities of a ouabain-sensitive Na+-K+-ATPase (a sarcolemmal membrane marker) of crude homogenate, 10,000 g, and 40,000 g membrane fractions were similar. These data indicate that training produces no detectable difference in the potential for adrenergic responses at the receptor level.

scholarly journals .BETA.-Adrenergic receptor adaptation after an acute exercise in rat myocardium.

1989 ◽  
Vol 39 (3) ◽  
pp. 447-454 ◽  
Author(s):  
Tetsuya IZAWA ◽  
Takao KOMABAYASHI ◽  
Kazuhiro SUDA ◽  
Shouhachiro SHINODA ◽  
Minoru TSUBOI
Keyword(s):  
Adrenergic Receptor ◽  
Acute Exercise ◽  
Rat Myocardium ◽  
Beta Adrenergic Receptor ◽  
Beta Adrenergic ◽  
Receptor Adaptation

Liver beta-adrenergic receptors, G proteins, and adenylyl cyclase activity in obesity-diabetes syndromes

1994 ◽  
Vol 266 (6) ◽  
pp. C1664-C1672 ◽  
Author(s):  
N. Begin-Heick
Keyword(s):  
Adenylyl Cyclase ◽  
G Proteins ◽  
Binding Sites ◽  
Adrenergic Receptor ◽  
Cyclase Activity ◽  
Adenylyl Cyclase Activity ◽  
Beta Adrenergic Receptor ◽  
Beta Adrenergic ◽  
Obesity And Diabetes ◽  
Liver Membranes

The ob and db genes produce similar hormonal anomalies in mice. Although the expression of the syndromes diverges with age, at 8-12 wk both ob/ob and db/db mice are hyperglycemic and hyperinsulinemic and show evidence of hypercorticoidism. Nevertheless, membranes isolated from livers of ob/ob and db/db mice behave differently in terms of adenylyl cyclase activity and beta-adrenergic receptor function. There are three times as many beta 2-adrenergic receptor binding sites and a threefold increase in the response to catecholamines in ob/ob mouse liver membranes than in comparable preparations from normal controls or db/db mice. By contrast, the two main G proteins of liver membranes (Gs alpha and Gi alpha 2) are less abundant in the mutants, ob/ob and db/db, than in their respective lean controls. Adrenalectomy normalizes the exaggerated response to beta-adrenergic agonists and the number of beta-adrenergic binding sites in the ob/ob mouse. This shows that the enhanced beta-adrenergic receptor response is linked to hypercorticoidism. Cellular maturation and differentiation (D. C. Watkins, J. K. Northrup, and C. C. Malbon, J. Biol. Chem. 262: 10651-10657, 1987) and diseases such as obesity and diabetes (cf. N. McFarlane-Anderson, J. Bailly, and N. Begin-Heick, Biochem. J. 282: 15-23, 1992) have been associated with modifications in the complement of G proteins detected in cells. However, the relationship among levels, types, and intracellular localization of G proteins in tissues and their influence on the transduction of the message to an effector system, such as adenylyl cyclase, are not yet well understood.

Exercise and insulin stimulate skeletal muscle glucose transport through different mechanisms

1989 ◽  
Vol 256 (2) ◽  
pp. E227-E230 ◽  
Author(s):  
E. Sternlicht ◽  
R. J. Barnard ◽  
G. K. Grimditch
Keyword(s):  
Skeletal Muscle ◽  
Glucose Transport ◽  
Binding Sites ◽  
Turnover Rate ◽  
Acute Exercise ◽  
Cytochalasin B ◽  
Number Of Binding Sites ◽  
Muscle Glucose Transport ◽  
Kinetics Of ◽  
Transport Molecules

This study was designed to examine the effects of acute exercise, insulin stimulation, and their combination on the kinetics of glucose transport in rat skeletal muscle. Sarcolemmal (SL) membranes were isolated from control (C), acute exercise (E), insulin-stimulated (I), and combined (E + I) rats. Michaelis-Menten kinetics indicated that the Vmax for glucose transport was increased after each perturbation compared with C but were not different from each other (E, 4,334 +/- 377; I, 4,424 +/- 668; E + I, 4,338 +/- 602; and C, 1,366 +/- 124 pmol.mg protein-1.s-1). The apparent Km was unchanged. Scatchard plots of cytochalasin B binding sites indicated that both I and E + I increased the number of binding sites compared both E and C (9.4 +/- 0.5 and 7.8 +/- 0.5 vs. 5.1 +/- 0.2 and 5.5 +/- 0.3 pmol/mg protein) without altering the dissociation constant. The increase in Vmax was greater than the increase in cytochalasin B binding sites indicating that both I and E + I caused an increase in the turnover rate of transport molecules as well as an increase in the total number of transport molecules. Because there was no change in the Km for glucose transport and no increase in cytochalasin B binding sites after exercise, the increase in Vmax was due solely to an increased turnover rate of existing transport molecules.

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