Beta-adrenergic receptors in guinea-pig myocardial tissue.
Stereospecific binding sites for (-) [3H]-alprenolol, a beta-adrenergic antagonist, have been identified in guinea-pig myocardial broken cell preparations. The concentration of the sites was 0.3 pmoles per mg of protein and the dissociation constant (at 37 degrees C) 10(-8) M. A close correlation between the ability of various beta-adrenergic antagonists to compete with tracer alprenolol binding and to block the response of isoprenaline-stimulated myocardial adenylate cyclase has been found. Low affinity sites for the labelled beta-adrenergic antagonist in contrast to stereospecific sites are heat stable and do not discriminate between the (-) and the (+) forms of the beta-adrenergic antagonists. Adenylate cyclase in guinea-pig myocardial tissue is poorly stimulated by isoprenaline or 5'-guanylylimidodiphosphate. This is attributed to a high basal activity which could be lowered by a preincubation at 37 degrees C.
D000262:Adenylyl Cyclases / Q000378:metabolism; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000319:Adrenergic beta-Antagonists / Q000378:metabolism / Q000494:pharmacology; D000526:Alprenolol / Q000378:metabolism; D000818:Animals; D001667:Binding, Competitive; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D009206:Myocardium / Q000032:analysis* / Q000201:enzymology; D011941:Receptors, Adrenergic / Q000032:analysis*; D011943:Receptors, Adrenergic, beta / Q000032:analysis* / Q000378:metabolism; D013237:Stereoisomerism
D000318:Adrenergic beta-Agonists; D000319:Adrenergic beta-Antagonists; D011941:Receptors, Adrenergic; D011943:Receptors, Adrenergic, beta; D000526:Alprenolol; D000262:Adenylyl Cyclases