The effect of triiodothyronine on insulin binding and action in rat adipocytes.
The effects of a short term (2 hour) incubation of 5 microM triiodothyronine (T3) on 125I-insulin binding and insulin stimulated (14C)-2-deoxy-D-glucose uptake in rat adipocytes was investigated. In the presence of 5 microM T3, (14C)-2-deoxy-D-glucose uptake was significantly decreased by 11 to 24% at insulin concentrations of 5 to 1000 microU/ml. The concentration of insulin eliciting a half maximal response for insulin stimulated (14C)-2-deoxy-D-glucose uptake was 11.5 microU/ml in the control, and 14.3 microU/ml in the T3 treated cells (p less than 0.01). T3 treated adipocytes bound 9 to 22% less 125I-labeled insulin yet the concentration of native insulin necessary to displace 50% of the bound 125I-labeled insulin was the same in the control and T3 treated cells (75 and 70 ng/ml, respectively). These studies indicate that the decreased sensitivity of T3 treated cells to insulin is in accordance with a decreased number of receptors with the same binding characteristics as those of the control cells. The decreased maximal uptake of (14C)-2-deoxy-D-glucose at saturating insulin levels is likely to be independent of receptor number and result from a second, undetermined alteration in the hexose transport system of adipocytes treated with T3.
D000273:Adipose Tissue / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D003837:Deoxy Sugars / Q000378:metabolism*; D003847:Deoxyglucose / Q000378:metabolism*; D007328:Insulin / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology*; D007700:Kinetics; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011972:Receptor, Insulin / Q000187:drug effects / Q000378:metabolism*; D014284:Triiodothyronine / Q000494:pharmacology*
D003837:Deoxy Sugars; D007328:Insulin; C008147:insulin, iodo-; D014284:Triiodothyronine; D003847:Deoxyglucose; D011972:Receptor, Insulin