Identification of tissue insulin receptors: use of a unique in vivo radioreceptor assay
Whitcomb, D.C.; O'Dorisio, T.M.; Cataland, S.; Shetzline, M.A.; Nishikawara, M.T.
American Journal of Physiology 249(6 Pt 1): E561-E567
1985
ISSN/ISBN: 0002-9513 PMID: 3909827 Document Number: 246237
An in vivo radioreceptor assay for polypeptide hormones has been developed and applied to the identification of tissue insulin receptors. The theoretical basis for this assay is presented elsewhere. 125I-insulin and 131I-albumin were infused into male rats with increasing amounts of unlabeled insulin. Plasma samples were taken at 1-min intervals until the animals were killed at 5 min. Tissue samples were excised and weighed and the activity due to each isotope counted. By comparing the differential distribution of the labeled tracers and applying the results to a compartment model, the specific, displaceable binding of insulin to tissue receptors could be demonstrated. Binding was detected in the liver, muscle, fat, adrenal glands, pancreas, small intestines, and spleen.