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Sökning: onr:"swepub:oai:gup.ub.gu.se/121473" > Autoimmunity in idi...

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FältnamnIndikatorerMetadata
00005123naa a2200589 4500
001oai:gup.ub.gu.se/121473
003SwePub
008240528s1994 | |||||||||||000 ||eng|
024a https://gup.ub.gu.se/publication/1214732 URI
040 a (SwePub)gu
041 a eng
042 9 SwePub
072 7a ref2 swepub-contenttype
072 7a art2 swepub-publicationtype
100a Magnusson, Yvonne,d 1957u Gothenburg University,Göteborgs universitet,Wallenberglaboratoriet,Wallenberg Laboratory4 aut0 (Swepub:gu)xmagyv
2451 0a Autoimmunity in idiopathic dilated cardiomyopathy. Characterization of antibodies against the beta 1-adrenoceptor with positive chronotropic effect.
264 1c 1994
520 a BACKGROUND: Autoantibodies against the beta 1-adrenoceptor have been detected in the sera of patients with idiopathic dilated cardiomyopathy (DCM). The mechanisms by which these autoantibodies can alter normal receptor function are investigated, and the results are interpreted in the light of the beneficial effects of beta 1-blockade in some of these patients. METHODS AND RESULTS: Autoantibodies against the beta 1-adrenoceptor, affinity purified from sera of patients with idiopathic DCM, were analyzed in a functional test system of spontaneously beating neonatal rat heart myocytes. Antibodies from rabbits immunized with peptides derived from the amino acid sequence of this receptor were also analyzed. Autoantibodies, against the second extracellular loop increased the beating frequency of isolated myocytes in a concentration-dependent manner, to approximately 80% of maximal isoproterenol stimulation. Rabbit anti-peptide antibodies against the second extracellular loop increased the beating frequency correspondingly. Autoantibodies and rabbit anti-peptide antibodies against the second extracellular loop were able to immunoprecipitate the unliganded receptor but not the antagonist-occupied receptor. In contrast, rabbit antibodies against the extracellular N-terminal sequence 34-57 of the beta 1-adrenoceptor were able to immunoprecipitate both the unliganded and the antagonist-occupied receptor although with no effect on the beating frequency of myocytes. The positive chronotropic effect of the antibodies was completely neutralized both by the addition of increasing concentrations of the beta 1-selective antagonist bisoprolol and by preincubation with the peptide corresponding to the second extracellular loop. The antibody-induced increase in beating frequency remained unchanged for more than 6 hours. This should be compared with the isoproterenol-stimulated beating frequency, which undergoes desensitization within 60 minutes. Addition of isoproterenol to autoantibody-stimulated myocytes resulted in only a small increase in beating frequency and did not cause desensitization. Antibodies had only a marginal effect on cyclic AMP production of stimulated cardiomyocytes compared with the 10-fold increase obtained after stimulation with isoproterenol. CONCLUSIONS: The second extracellular loop of the beta 1-adrenoceptor is a specific target for antibodies with stimulatory activity detected in patients with idiopathic DCM. The antibodies have a positive chronotropic effect on isolated rat heart myocytes. Autoantibody stimulation does not cause the normal agonist-induced desensitization phenomena of the effector system. These findings could contribute to our understanding of the pathophysiological mechanisms of the autoantibodies and of the beneficial effect of beta 1-blocking agents in the treatment of patients with idiopathic DCM.
650 7a MEDICIN OCH HÄLSOVETENSKAPx Medicinska och farmaceutiska grundvetenskaperx Mikrobiologi inom det medicinska området0 (SwePub)301092 hsv//swe
650 7a MEDICAL AND HEALTH SCIENCESx Basic Medicinex Microbiology in the medical area0 (SwePub)301092 hsv//eng
653 a Aged
653 a Amino Acid Sequence
653 a Animals
653 a Autoantibodies
653 a immunology
653 a physiology
653 a Autoimmunity
653 a Cardiomyopathy
653 a Dilated
653 a immunology
653 a Dose-Response Relationship
653 a Immunologic
653 a Female
653 a Heart Rate
653 a Humans
653 a Male
653 a Middle Aged
653 a Molecular Sequence Data
653 a Rats
653 a Rats
653 a Wistar
653 a Receptors
653 a Adrenergic
653 a beta-1
653 a immunology
700a Wallukat, G4 aut
700a Waagstein, Finn,d 1938u Gothenburg University,Göteborgs universitet,Hjärt-kärlinstitutionen,Cardiovascular Institute4 aut0 (Swepub:gu)xwaafi
700a Hjalmarson, Agneta,d 1943u Gothenburg University,Göteborgs universitet,Hjärt-kärlinstitutionen,Cardiovascular Institute4 aut0 (Swepub:gu)xhjaag
700a Hoebeke, Johan4 aut
710a Göteborgs universitetb Wallenberglaboratoriet4 org
773t Circulationg 89:6, s. 2760-7q 89:6<2760-7x 0009-7322
8564 8u https://gup.ub.gu.se/publication/121473

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