Overexpression of Cardiomyocyte α1A-Adrenergic Receptors Attenuates Postinfarct Remodeling by Inducing Angiogenesis Through Heterocellular Signaling

Xin Zhao, Poornima Balaji, Ronald Pachon, Daniella M. Beniamen, Dorothy E. Vatner, Robert M. Graham, Stephen F. Vatner

Research output: Contribution to journalArticle

12 Scopus citations

Abstract

Objective-Stimulation of cardiac α1A-adrenergic receptors (α1A-AR) has been proposed for treatment of heart failure, since it increases myocardial contractility. We investigated a different mechanism, induction of angiogenesis. Approach and Results-Four to 6 weeks after permanent coronary artery occlusion, transgenic rats with cardiomyocyte-specific α1A-adrenergic receptor overexpression had less remodeling than their nontransgenic littermates, with less fibrosis, hypertrophy and lung weight, and preserved left ventricular ejection fraction and wall stress (all P<0.05). Coronary blood flow, measured with microspheres, increased in the infarct zone in transgenic rats compared with nontransgenic littermates (1.4±0.2 versus 0.5±0.08 mL min-1 g-1; P<0.05), which is consistent with angiogenesis, as reflected by a 20% increase in capillary density in the zone adjacent to the infarct. The question arose, how does transgenic overexpression of a gene in cardiomyocytes induce angiogenesis? We identified a paracrine mechanism, whereby vascular endothelial growth factor-A mRNA and protein were increased in isolated transgenic cardiomyocytes and also by nontransgenic littermate cardiomyocytes treated with an α1A-agonist, resulting in angiogenesis. Conditioned medium from cultured cardiomyocytes treated with an α1A agonist enhanced human umbilical vein endothelial cell tubule formation, which was blocked by an anti-vascular endothelial growth factor-A antibody. Moreover, improved cardiac function, blood flow, and increased capillary density after chronic coronary artery occlusion in transgenic rats were blocked by either a mitogen ERK kinase (MEK) or a vascular endothelial growth factor-A inhibitor. Conclusion-Cardiomyocyte-specific overexpression of the α1A-adrenergic receptors resulted in enhanced MEK-dependent cardiomyocyte vascular endothelial growth factor-A expression, which stimulates angiogenesis via a paracrine mechanism involving heterocellular cardiomyocyte/endothelial cell signaling, protecting against remodeling and heart failure after chronic coronary artery occlusion.

Original languageEnglish (US)
Pages (from-to)2451-2459
Number of pages9
JournalArteriosclerosis, Thrombosis, and Vascular Biology
Volume35
Issue number11
DOIs
StatePublished - Nov 1 2015

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All Science Journal Classification (ASJC) codes

  • Cardiology and Cardiovascular Medicine

Keywords

  • alpha adrenergic receptors
  • angiogenesis
  • cardiac
  • heart failure
  • myocardial infarction
  • myocytes
  • vascular endothelial growth factor

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