[Interaction of insulin and its receptors in the muscles: specific I125 binding with plasma membranes of the skeletal muscle of rat]

Abstract

A preparation of plasmatic membranes of the rat skeletal muscle was obtained which was used to characterize the interaction of insulin with its receptors in the myocyte. It was shown that insulin-125I binding by the membranes depended on the incubation time and temperature; the maximum binding occurred at 4 degrees, although the binding rate was low at this temperature. The degrading of labeled insulin at 4 degrees C did not exceed 1% in the course of 24 hours of incubation with the membranes. Crude pig insulin inhibited the binding by 50% in a dose of 2.7 nMol; fish insulin (biologically less active) in a dose which was 25 times greater, the other hormones studied were completely ineffective in this respect. A curve with a bend obtained by the treatment of these data after Sketchard indicated the heterogeneity of the receptors under study or their interaction of the "negative cooperation" type. A conclusion was drawn on the absence of any significant differences between the insulin receptors in the muscles in comparison with its receptors in other target cells.