title: Cardiac contractility in Antarctic teleost is modulated by nitrite through xanthine oxidase and cytochrome p-450 nitrite reductase.
abstract: In mammalian and non-mammalian vertebrates, nitrite anion, the largest pool of intravascular and tissue nitric oxide storage, represents a key player of many biological processes, including cardiac modulation. As shown by our studies on Antarctic teleosts, nitrite-dependent cardiac regulation is of great relevance also in cold-blooded vertebrates. This study analysed the influence elicited by nitrite on the performance of the perfused beating heart of two Antarctic stenotherm teleosts, the haemoglobinless Chionodraco hamatus (icefish) and the red-blooded Trematomus bernacchii. Since haemoglobin is crucial in nitric oxide homeostasis, the icefish, a naturally occurring genetic knockout for this protein, provides exclusive opportunities to investigate nitric oxide/nitrite signaling. In vivo, nitrite conversion to nitric oxide requires the nitrite reductase activity of xanthine oxidase and cytochrome P-450, thus the involvement of these enzymes was also evaluated. We showed that, in C. hamatus and T. bernacchii, nitrite influenced cardiac performance by inducing a concentration-dependent positive inotropic effect which was unaffected by nitric oxide scavenging by PTIO in C. hamatus, while it was abolished in T. bernacchii. Specific inhibition of xanthine oxidase and cytochrome P-450 revealed, in the two teleosts, that the nitrite-dependent inotropism required the nitrite reductase activity of both enzymes. We also found that xanthine oxidase is more expressed in C. hamatus than in T. bernacchii, while the opposite was observed concerning cytochrome P-450. Results suggested that in the heart of C. hamatus and T. bernacchii, nitrite is an integral physiological source of nitric oxide with important signaling properties, which require the nitrite reductase activity of xanthine oxidase and cytochrome P-450.
authors.affiliation: Department of Biology, Ecology and Earth Science, University of Calabria, 87030 Arcavacata di Rende, CS, Italy.
authors.forename: Filippo
authors.initials: F
authors.lastname: Garofalo
authors.affiliation: Department of Biology, Ecology and Earth Science, University of Calabria, 87030 Arcavacata di Rende, CS, Italy.
authors.forename: Daniela
authors.initials: D
authors.lastname: Amelio
authors.affiliation: Department of Biology, Ecology and Earth Science, University of Calabria, 87030 Arcavacata di Rende, CS, Italy.
authors.forename: Alfonsina
authors.initials: A
authors.lastname: Gattuso
authors.affiliation: Department of Biology, Ecology and Earth Science, University of Calabria, 87030 Arcavacata di Rende, CS, Italy.
authors.forename: Maria Carmela
authors.initials: MC
authors.lastname: Cerra
authors.affiliation: Department of Biology, Ecology and Earth Science, University of Calabria, 87030 Arcavacata di Rende, CS, Italy. Electronic address: danielapellegrino@unical.it.
authors.forename: Daniela
authors.initials: D
authors.lastname: Pellegrino
mesh_terms: D000818:Animals; D000864:Antarctic Regions; D005260:Female; D008297:Male; D009200:Myocardial Contraction / Q000502:physiology*; D009251:NADPH-Ferrihemoprotein Reductase / Q000378:metabolism*; D009573:Nitrites / Q000378:metabolism*; D010473:Perciformes / Q000378:metabolism* / Q000502:physiology*; D013318:Stroke Volume / Q000502:physiology; D014969:Xanthine Oxidase / Q000378:metabolism*
chemical_list: D009573:Nitrites; D014969:Xanthine Oxidase; D009251:NADPH-Ferrihemoprotein Reductase
keywords: Antarctic teleosts; Cytochrome P-450; Icefish; Nitric oxide; Nitrite; Xanthine oxidase