期刊
JOURNAL OF EXPERIMENTAL BIOLOGY
卷 222, 期 14, 页码 -出版社
COMPANY BIOLOGISTS LTD
DOI: 10.1242/jeb.206045
关键词
Intermittent hypoxia; HSP70; Anabolism; Preconditioning; AMP-activated protein
类别
资金
- Natural Sciences and Engineering Research Council of Canada (NSERC)
- NSERC
Many fish naturally encounter a daily cycle of hypoxia, but it is unclear whether this exposure hardens hypoxia-intolerant fish to future hypoxia or leads to accumulated stress and death. The rainbow trout (Oncorhynchus mykiss) is a putatively hypoxia-sensitive species found in rivers and estuaries that may routinely experience hypoxic events. Trout were exposed to one of four 135 h treatments in a swim-tunnel respirometer: (1) air-saturated control (20.7 kPa P-O2); (2) diel cycling O-2 (20.7-4.2 kPa P-O2 over 24 h); (3) acute hypoxia (130 h at 20.7 kPa P-O2 followed by 5 h at 4.2 kPa P-O2); and (4) the mean oxygen tension (12.4 kPa P-O2) experienced by the diel cycled fish. Some responses were similar in diel O-2 cycled and mean P(O2 )treated fish, but overall, exposure to ecologically representative diel hypoxia cycles improved hypoxia tolerance. Diel hypoxia-induced protective responses included increased inducible HSP70 concentration and mean corpuscular hemoglobin concentration, as well as reduced plasma cortisol. Acclimation to diel hypoxia allowed metabolic rates to decline during hypoxia, reduced oxygen debt following subsequent exposures, and allowed fish to return to an anabolic phenotype. The data demonstrate that acute diel cycling hypoxia improves hypoxia tolerance in previously intolerant fish through the activation of cellular protective mechanisms and a reduction in metabolic O-2 requirements.
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