beta-Adrenergic receptors in rat brain.
125I-Iodohydroxybenzylpindolol ([125I] IHYP), a potent beta-adrenergic receptor antagonist, has been used to study beta-adrenergic receptors in rat brain. Binding of [125I] IHYP (30 pM) to a membrane fraction min and dissociation took place with a half time of about 16 min. Phentolamine (10(-4) M) decreased non-receptor binding but it had no effect on the binding of [125I] IHYP to beta-adrenergic receptors in cortex, cerebellum or caudate. In the presence of phentolamine specific binding (defined as binding which was blocked by 0.3 muM dl-propranolol) represented 70-85% of total binding. The binding of [125I] IHYP was inhibited by beta-adrenergic agonists and antagonists. d-Stereoisomers were 2-3 orders of magnitude less potent than the corresponding 1-isomers. The denstiy of [125I] IHYP binding sites was studied in membrane fractions from cerebral cortex, cerebellum, and caudate nucleus by means of Scatchard analysis. The K(D) of [125I] IHYP was similar in the three regions studied, and the density of [125I] IHYP binding sites was approximately 50% greater in the cortex and caudate than in the cerebellum. The Hill coefficient for the binding of [125I] IHYP to membranes from cerebral cortex was 1.02. The properties of the binding of [125I] IHYP are similar to those which would be expected of binding to beta-adrenergic receptors in vitro.
D000318:Adrenergic beta-Agonists / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D001933:Brain Stem / Q000378:metabolism; D002421:Caudate Nucleus / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002531:Cerebellum / Q000378:metabolism; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism; D007031:Hypothalamus / Q000378:metabolism; D007545:Isoproterenol / Q000494:pharmacology; D007700:Kinetics; D008297:Male; D009419:Nerve Tissue Proteins / Q000378:metabolism; D010646:Phentolamine / Q000494:pharmacology; D010869:Pindolol / Q000031:analogs & derivatives* / Q000378:metabolism; D011433:Propranolol / Q000494:pharmacology; D011485:Protein Binding; D051381:Rats; D011941:Receptors, Adrenergic / Q000187:drug effects; D013237:Stereoisomerism
D000318:Adrenergic beta-Agonists; D009419:Nerve Tissue Proteins; D011941:Receptors, Adrenergic; C011878:iodohydroxybenzylpindolol; D011433:Propranolol; D010869:Pindolol; D007545:Isoproterenol; D010646:Phentolamine