title: Beta1-adrenoceptor antibodies induce apoptosis in adult isolated cardiomyocytes.
abstract: beta(1)-Adrenoceptor autoantibodies are present in about 30% of patients suffering from dilated cardiomyopathy. The apoptotic effects mediated by beta(1)-adrenoceptor antibodies remain to be studied. Monoclonal antibodies were raised against a synthetic peptide corresponding to the second extracellular loop of the human beta(1)-adrenoceptor in balb/C mouse, and were characterized by enzyme immunoassay. Purified immunoglobulin G from nonimmunized animals (controls) did not influence the rate of apoptosis. beta(1)-Adrenoceptor antibodies caused a dose-related increase in apoptotic cells: annexin test (dilution 1:2: 21+/-1.1% apoptotic cells vs. 4+/-0.4% apoptotic cells in controls; p<0.01); TdT-mediated dUTP nick end labeling (TUNEL) test (dilution 1:2: 26+/-2% apoptotic cells vs. 10+/-2% apoptotic cells in controls; p<0.01). The effect of the beta(1)-adrenoceptor antibodies was blocked by the antigenic peptide and by the antagonist metoprolol (10 micromol/l). The apoptotic effect induced by isoproterenol was attenuated by the beta(1)-adrenoceptor antibody. After pre-incubation of cardiomyocytes with the protein kinase A inhibitor Rp-Adenosine-3',5'-cyclic monophosphothioate triethylamine (RpcAMPS), beta(1)-adrenoceptor antibody was not capable of inducing an increase of the rate of apoptosis. beta(1)-Adrenoceptor antibodies induced apoptosis in adult rat cardiomyocytes via the protein kinase A cascade.
authors.affiliation: Klinik für Innere Medizin B, Medizinische Fakultät, Ernst-Moritz-Arndt-Universität, Fr.-Loefflerstr. 23a, D-17487, Greifswald, Germany. staudt@uni-greifwald.de
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Staudt
authors.forename: Reza
authors.initials: R
authors.lastname: Mobini
authors.forename: Michael
authors.initials: M
authors.lastname: Fu
authors.forename: Stephan B
authors.initials: SB
authors.lastname: Felix
authors.forename: Jens Peter
authors.initials: JP
authors.lastname: Kühn
authors.forename: Alexander
authors.initials: A
authors.lastname: Staudt
mesh_terms: D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000494:pharmacology*; D017209:Apoptosis; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D020287:In Situ Nick-End Labeling; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D008790:Metoprolol / Q000494:pharmacology; D051379:Mice; D032383:Myocytes, Cardiac / Q000166:cytology / Q000187:drug effects*; D010446:Peptide Fragments / Q000276:immunology; D051381:Rats; D018342:Receptors, Adrenergic, beta-1 / Q000276:immunology*
chemical_list: D000318:Adrenergic beta-Agonists; D000319:Adrenergic beta-Antagonists; D000911:Antibodies, Monoclonal; D010446:Peptide Fragments; D018342:Receptors, Adrenergic, beta-1; D017868:Cyclic AMP-Dependent Protein Kinases; D008790:Metoprolol; D007545:Isoproterenol