Insulin-like action of catecholamines and Ca2+ to stimulate glucose transport and GLUT4 translocation in perfused rat heart.
The uptake of 2-deoxyglucose by perfused rat hearts was compared to the distribution of the insulin-regulatable glucose transporter (GLUT4) in membrane preparations from the same hearts. The hearts were treated with the alpha-adrenergic combination of epinephrine + propranolol, the beta-adrenergic agonist isoproterenol, high (8 mM) Ca2+ concentrations, insulin and the alpha adrenergic combination or insulin alone. Epinephrine (1 microM) + propranolol (10 microM), isoproterenol (10 microM), high Ca2+, insulin (1 microM) + epinephrine (1 microM) + propranolol (10 microM) and insulin (1 microM) each led to an increase in 2-deoxyglucose uptake and a shift in the recovery of the GLUT4 from a high-speed pellet membrane fraction (putatively intracellular) to a low-speed pellet membrane fraction (putatively sarcolemmal). There were significant correlations (r = -0.673, P less than 0.001) between the stimulation of 2-deoxyglucose uptake and the loss of GLUT4 from the intracellular membrane fraction, or the increase in the sarcolemmal fraction. The data provide evidence that the GLUT4 is translocated by agents that stimulate glucose transport in heart, and therefore this mechanism is not restricted to insulin.
PubMed Abstracts
PubMed Abstracts