title: Isoproterenol-induced desensitization to the positive inotropic effect of isoproterenol in ventricular strips isolated from carp heart (Cyprinus carpio).
abstract: Whether the positive inotropic effect of isoproterenol in ventricular strips of carp heart is altered by previous exposure to the agonist was studied. Isoproterenol produced a concentration-dependent positive inotropic effect in these preparations which was competitively antagonized by propranolol. Isoproterenol dose-response curves were shifted significantly downward and to the right after previous treatment with and removal of isoproterenol. The desensitization could be demonstrated after 5 min incubation and near maximal desensitization was observed after 30 min exposure to 1000 nM isoproterenol. The responsiveness was only partially recovered after 180 min incubation in drug-free medium. Isoproterenol produces a rapidly developing desensitization to inotropic effects of the beta-adrenergic agonist. This phenomenon may be mediated by alterations in beta-adrenergic receptors, adenylate cyclase and/or the beta receptor-adenylate cyclase coupling mechanism.
authors.forename: K
authors.initials: K
authors.lastname: Temma
authors.forename: T
authors.initials: T
authors.lastname: Hirata
authors.forename: T
authors.initials: T
authors.lastname: Kitazawa
authors.forename: H
authors.initials: H
authors.lastname: Kondo
mesh_terms: D000818:Animals; D002122:Calcium Chloride / Q000494:pharmacology; D002347:Carps; D004305:Dose-Response Relationship, Drug; D006352:Heart Ventricles / Q000187:drug effects; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology*; D009200:Myocardial Contraction / Q000187:drug effects*; D011433:Propranolol / Q000494:pharmacology; D016276:Ventricular Function
chemical_list: D011433:Propranolol; D007545:Isoproterenol; D002122:Calcium Chloride