Inhibition of [3H]-dihydroalprenolol binding to rat cardiac membranes of various beta-blocking agents.
Binding of [3-H]-dihydroalprenolol ([3-H]-DHA) to rat cardiac membranes was rapid and reversible (k1 = 0.633-0.701 x 10(6) M(-1) S(-1) And k(-1) = 0.0017-0.0043 s(-1). 2 [3-H]-DHA bound to a single class of binding sites with an equilibrium dissociation constant (Kd25degreesc) of 5.7+/-1.1 x 10(-9) M. 3 This binding was specific and the order of potency of adrenoceptor agonists in competing for the binding sites was (-)-isoproterenol greater than (+/-)-isoproternol greater than (+)-isoproterenol greater than (-)-adrenaline greater than (-)-noradrenaline. This was in agreement with the beta1 nature of the cardiac beta-receptors. 4 Cardioselective beta-blockers (i.e. metoprolol, acebutolol and practolol) were shown to have lower binding site affinities, when compared to other blockers. This may be related to steric hindrance by the side-chain at the aromatic end of these molecules.
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000526:Alprenolol / Q000031:analogs & derivatives* / Q000378:metabolism; D000818:Animals; D004353:Drug Evaluation, Preclinical / Q000379:methods; D006321:Heart / Q000187:drug effects*; D066298:In Vitro Techniques; D008297:Male; D011485:Protein Binding / Q000187:drug effects; D011869:Radioligand Assay; D051381:Rats; D011941:Receptors, Adrenergic / Q000302:isolation & purification
D000319:Adrenergic beta-Antagonists; D011941:Receptors, Adrenergic; D000526:Alprenolol