Catecholamine-induced insulin resistance of glucose transport in isolated rat adipocytes.
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.
D000255:Adenosine Triphosphate / Q000378:metabolism; D000273:Adipose Tissue / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D005947:Glucose / Q000378:metabolism*; D066298:In Vitro Techniques; D007333:Insulin Resistance; D007545:Isoproterenol / Q000494:pharmacology*; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors
D000255:Adenosine Triphosphate; D005947:Glucose; D007545:Isoproterenol; D009638:Norepinephrine