Antioxidants (Apr 2022)

An ACE2-Alamandine Axis Modulates the Cardiac Performance of the Goldfish <i>Carassius auratus</i> via the NOS/NO System

  • Mariacristina Filice,
  • Rosa Mazza,
  • Sandra Imbrogno,
  • Olga Mileti,
  • Noemi Baldino,
  • Amilcare Barca,
  • Gianmarco Del Vecchio,
  • Tiziano Verri,
  • Alfonsina Gattuso,
  • Maria Carmela Cerra

DOI
https://doi.org/10.3390/antiox11040764
Journal volume & issue
Vol. 11, no. 4
p. 764

Abstract

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Alamandine is a peptide of the Renin Angiotensin System (RAS), either generated from Angiotensin A via the Angiotensin Converting Enzyme 2 (ACE2), or directly from Ang-(1–7). In mammals, it elicits cardioprotection via Mas-related G-protein-coupled receptor D (MrgD), and the NOS/NO system. In teleost fish, RAS is known to modulate heart performance. However, no information is available on the presence of a cardioactive ACE2/Alamandine axis. To fill this gap, we used the cyprinid teleost Carassius auratus (goldfish) for in silico and in vitro analyses. Via the NCBI Blast P suite we found that in cyprinids ace2 is phylogenetically detectable in a subcluster of proteins including ace2-like isoforms, and is correlated with a hypoxia-dependent pathway. By real-time PCR, Western Blotting, and HPLC, ACE2 and Alamandine were identified in goldfish heart and plasma, respectively. Both increased after chronic exposure to low O2 (2.6 mg O2 L−1). By using an ex-vivo working goldfish-heart preparation, we observed that in vitro administration of exogenous Alamandine dose-dependently stimulates myocardial contractility starting from 10−11 M. The effect that involved Mas-related receptors and PKA occurred via the NOS/NO system. This was shown by exposing the perfused heart to the NOS inhibitor L-NMMA (10−5 M) that abolished the cardiac effect of Alamandine and was supported by the increased expression of the phosphorylated NOS enzyme in the extract from goldfish heart exposed to 10−10 M Alamandine. Our data are the first to show that an ACE2/Alamandine axis is present in the goldfish C. auratus and, to elicit cardiac modulation, requires the obligatory involvement of the NOS/NO system.

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