title: Cardiac effects of beta-adrenergic receptor antagonists: beta-moderators versus beta-blockers.
abstract: Two adrenergic receptor antagonists, acebutolol and propranolol, were observed to depress rabbit heart contractile force and adrenaline-stimulated adenylate cyclase activity at 1 X 10-(5) to 1 X 10-(3) M and 1 X 10-(6) to 1 X 10-(3) M concentrations, respectively. Acebutolol depressed sarcoplasmic reticular and mitochondrial calcium uptake at 5 X 10-(3) to 10-(2) M concentrations. On the other hand, propranolol was found to decrease calcium uptake activities of sarcoplasmic reticular and mitochondrial fractions at 1 X 10-(4) to 1 X 10-(2) M and 1 X 10-(3) to 1 X 10-(2) M concentrations, respectively. On the basis of these results with calcium transport systems, it is proposed that beta-antagonists with a mild depressant effect, such as acebutolol, may be called beta-moderators, whereas those with a strong effect, such as propranolol, may be called beta-blockers.
mesh_terms: D000070:Acebutolol / Q000494:pharmacology; D000262:Adenylyl Cyclases / Q000032:analysis; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism; D004837:Epinephrine / Q000494:pharmacology; D006321:Heart / Q000187:drug effects*; D066298:In Vitro Techniques; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects; D011433:Propranolol / Q000494:pharmacology; D011817:Rabbits; D011943:Receptors, Adrenergic, beta / Q000187:drug effects
chemical_list: D000319:Adrenergic beta-Antagonists; D011943:Receptors, Adrenergic, beta; D000070:Acebutolol; D011433:Propranolol; D000262:Adenylyl Cyclases; D002118:Calcium; D004837:Epinephrine