Different patterns of chronic hypoxia lead to hierarchical adaptive mechanisms in goldfish metabolism.

Autor:	Thoral E; Univ. Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR 5023 LEHNA, Villeurbanne 69622, France., Farhat E; Biology Department, University of Ottawa, Ottawa, ON, Canada, K1N 6N5., Roussel D; Univ. Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR 5023 LEHNA, Villeurbanne 69622, France., Cheng H; Biology Department, University of Ottawa, Ottawa, ON, Canada, K1N 6N5., Guillard L; Univ. Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR 5023 LEHNA, Villeurbanne 69622, France., Pamenter ME; Biology Department, University of Ottawa, Ottawa, ON, Canada, K1N 6N5.; University of Ottawa Brain and Mind Research Institute, Ottawa, ON, Canada, K1N 6N5., Weber JM; Biology Department, University of Ottawa, Ottawa, ON, Canada, K1N 6N5., Teulier L; Univ. Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR 5023 LEHNA, Villeurbanne 69622, France.
Jazyk:	angličtina
Zdroj:	The Journal of experimental biology [J Exp Biol] 2022 Jan 01; Vol. 225 (1). Date of Electronic Publication: 2022 Jan 06.
DOI:	10.1242/jeb.243194
Abstrakt:	Some hypoxia-tolerant species, such as goldfish, experience intermittent and severe hypoxia in their natural habitat, causing them to develop multiple physiological adaptations. However, in fish, the metabolic impact of regular hypoxic exposure on swimming performance in normoxia is less well understood. Therefore, we experimentally tested whether chronic exposure to constant (30 days at 10% air saturation) or intermittent hypoxia (3 h in normoxia and 21 h in hypoxia, 5 days a week) would result in similar metabolic and swimming performance benefits after reoxygenation. Moreover, half of the normoxic and intermittent hypoxic fish were put on a 20-day normoxic training regime. After these treatments, metabolic rate (standard and maximum metabolic rates: SMR and MMR) and swimming performance [critical swimming speed (Ucrit) and cost of transport (COT)] were assessed. In addition, enzyme activities [citrate synthase (CS), cytochrome c oxidase (COX) and lactate dehydrogenase (LDH)] and mitochondrial respiration were examined in red muscle fibres. We found that acclimation to constant hypoxia resulted in (1) metabolic suppression (-45% SMR and -27% MMR), (2) increased anaerobic capacity (+117% LDH), (3) improved swimming performance (+80% Ucrit, -71% COT) and (4) no changes at the mitochondrial level. Conversely, the enhancement of swimming performance was reduced following acclimation to intermittent hypoxia (+45% Ucrit, -41% COT), with a 55% decrease in aerobic scope, despite a significant increase in oxidative metabolism (+201% COX, +49% CS). This study demonstrates that constant hypoxia leads to the greatest benefit in swimming performance and that mitochondrial metabolic adjustments only provide minor help in coping with hypoxia. Competing Interests: Competing interests The authors declare no competing or financial interests. (© 2022. Published by The Company of Biologists Ltd.)
Databáze:	MEDLINE
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