title: [Mechanism of the slow inotropic response of the mouse atrium mediated by the beta2-adrenoreceptor].
abstract: The abundant beta2-adrenoceptors (AR) expression was revealed in the mouse atrial cardiomyocytes, albeit its function is poorly understood. Recently we revealed the slow developing (for 20-40 min) positive inotropic effect in the mouse atrium which was induced by the specific agonist of the beta2-adrenoceptors (5 mkM fenoterol) and the task of this study involved investigation of the found effect. It was shown that stimulation of beta2-AR is enough for rapid triggering of up-regulation of two signalling pathways that have the opposite influence on the contraction force. On one hand, activation of the adenylate cyclase--protein kinase A cascade occurs leading to increasing of intracellular Ca2+ concentration and amplitude of contraction; on the other hand, activation of the NO-synthase and enhance of NO production occurs which prevents the potentiating of the contraction force. During the first 15-20 minutes, superposition of these activation effects was revealed, which prevented the contraction strength increasing. Then the positive inotropic effects occurred due to the decreasing of NO production. It was shown that L-type Ca-channels and ryanodine receptors were the key targets incorporated in the beta2 adrenoreceptors signalling puzzle.
authors.forename: Iu G
authors.initials: IuG
authors.lastname: Odnoshivkina
authors.forename: A M
authors.initials: AM
authors.lastname: Petrov
authors.forename: A L
authors.initials: AL
authors.lastname: Zefirov
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism; D058666:Adrenergic beta-2 Receptor Agonists / Q000494:pharmacology; D000818:Animals; D016275:Atrial Function; D002118:Calcium / Q000032:analysis* / Q000378:metabolism; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000494:pharmacology / Q000502:physiology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D005280:Fenoterol / Q000494:pharmacology; D006801:Humans; D007097:Imines / Q000494:pharmacology; D051379:Mice; D009200:Myocardial Contraction; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000502:physiology*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009543:Nifedipine / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000378:metabolism; D018343:Receptors, Adrenergic, beta-2 / Q000502:physiology*; D015398:Signal Transduction; D013873:Thionucleotides / Q000494:pharmacology
chemical_list: D058666:Adrenergic beta-2 Receptor Agonists; D007097:Imines; D018343:Receptors, Adrenergic, beta-2; D013873:Thionucleotides; D005280:Fenoterol; C016957:adenosine-3',5'-cyclic phosphorothioate; D009569:Nitric Oxide; C014925:RMI 12330A; D000242:Cyclic AMP; D019001:Nitric Oxide Synthase; D017868:Cyclic AMP-Dependent Protein Kinases; D000262:Adenylyl Cyclases; D009543:Nifedipine; D002118:Calcium; D019331:NG-Nitroarginine Methyl Ester