Angiotensin-(1-7) binds to specific receptors on cardiac fibroblasts to initiate antifibrotic and antitrophic effects

Michikado Iwata, Randy T. Cowling, Devorah Gurantz, Cristina Moore, Shen Zhang, Jason X.J. Yuan, Barry H. Greenberg

Research output: Contribution to journalArticle

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Abstract

ANG-(1-7) improves the function of the remodeling heart. Although this peptide is generated directly within the myocardium, the effects of ANG-(1-7) on cardiac fibroblasts that play a critical role in cardiac remodeling are largely unknown. We tested the hypothesis that specific binding of ANG-(1-7) to cardiac fibroblasts regulates cellular functions that are involved in cardiac remodeling. 125I-labeled ANG-(1-7) binding assays identified specific binding sites of ANG-(1-7) on adult rat cardiac fibroblasts (ARCFs) with an affinity of 11.3 nM and a density of 131 fmol/mg protein. At nanomolar concentrations, ANG-(1-7) interacted with specific sites that were distinct from ANG II type 1 and type 2 receptors without increasing cytosolic Ca2+ concentration. At these concentrations, ANG-(1-7) had inhibitory effects on collagen synthesis as assessed by [3H]proline incorporation and decreased mRNA expression of growth factors in ARCFs. These effects of ANG-(1-7) contrasted with effects of ANG II. Pretreatment of ARCFs with ANG-(1-7) inhibited ANG II-induced increases in collagen synthesis and in mRNA expression of growth factors, including endothelin-1 and leukemia inhibitory factor. ANG-(1-7) pretreatment also inhibited the stimulatory effects of conditioned medium from ANG II-treated ARCFs on [3H]leucine incorporation and atrial natriuretic factor mRNA expression, markers of hypertrophy, in cardiomyocytes. Thus ANG-(1-7) interacted with specific receptors on ARCFs to exert potential antifibrotic and antitrophic effects that could reverse ANG II effects. These results suggest that ANG-(1-7) may play an important role in the heart in regulating cardiac remodeling.

Original languageEnglish (US)
Pages (from-to)H2356-H2363
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume289
Issue number6 58-6
DOIs
StatePublished - Dec 1 2005

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Keywords

  • Angiotensin receptors
  • Cardiac remodeling
  • Renin-angiotensin system

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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