An assay for beta-adrenergic receptors in isolated human fat cells.
The beta-adrenergic receptors have been characterized in isolated human adipocytes using a potent beta-adrenergic antagonist (-)-[3H]dihydroalprenolol. Binding of (-)-[3H]dihydroalprenolol to isolated fat cells was stereospecific and saturable, the maximum number of binding sites calculated being 7.8 +/- 2.2 pmol of bound ligand/10(7) cells, corresponding to 450,000 binding sites/cell. The dissociation constant was estimated to be 2.7 +/- 1.1 nM. The results with competition-inhibition experiments using beta-adrenergic agonists and antagonists indicated that the binding sites in isolated adipocytes were predominantly of the beta1-subtype; about 80% of the receptors were of this type. With the present method, specific beta-adrenergic receptor number and affinity in isolated human adipocytes could be determined in about 1 g of human adipose tissue.
D000273:Adipose Tissue / Q000032:analysis*; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D001667:Binding, Competitive; D004082:Dihydroalprenolol / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D011433:Propranolol / Q000378:metabolism; D011941:Receptors, Adrenergic / Q000032:analysis*; D011943:Receptors, Adrenergic, beta / Q000032:analysis*; D013997:Time Factors
D000318:Adrenergic beta-Agonists; D011941:Receptors, Adrenergic; D011943:Receptors, Adrenergic, beta; D004082:Dihydroalprenolol; D011433:Propranolol