title: Lack of functional influence by prenalterol through alpha 1-adrenoceptors in rat myocardium.
abstract: Some of the cardiac properties of the partial beta-agonist prenalterol may indicate a contribution from alpha 1-adrenergic stimulation. We therefore studied whether prenalterol interacted with alpha 1-adrenoceptors in rat myocardium. Combination with propranolol did not reveal an alpha 1-adrenergic inotropic effect of prenalterol in papillary muscles. Neither did prenalterol block the alpha 1-adrenergic response to phenylephrine. In myocardial cells, prenalterol inhibited 3H-prazosin binding to alpha 1-adrenoceptors only at very high concentrations. Prenalterol thus exhibited no functionally important interactions with alpha 1-adrenoceptors in myocardium, and its properties cannot be accounted for in terms of contribution from alpha 1-adrenergic effects.
mesh_terms: D000818:Animals; D002316:Cardiotonic Agents / Q000378:metabolism / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects*; D010210:Papillary Muscles / Q000502:physiology; D011217:Practolol / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D011224:Prazosin / Q000378:metabolism; D011294:Prenalterol; D051381:Rats; D011919:Rats, Inbred Strains; D011941:Receptors, Adrenergic / Q000187:drug effects*; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects* / Q000378:metabolism
chemical_list: D002316:Cardiotonic Agents; D011941:Receptors, Adrenergic; D011942:Receptors, Adrenergic, alpha; D011294:Prenalterol; D011217:Practolol; D011224:Prazosin