We investigated the effects of a diet enriched in omega-3 (ω3) polyunsaturated fatty acids (PUFA) and vitamin E on responses of sturgeon (Acipenser naccarii) to hypoxia. After 3 months of feeding, there were significant increases in ω3 PUFA in liver and muscle, and of vitamin E in muscle, of fish fed the enriched diet (ED) compared with fish on a standard diet (SD), indicating that tissue composition is influenced by diet. Acute exposure to hypoxia (10 min at 10.8 kPa water O2 tension, PwO2 had no effect on oxygen consumption (VO2, increased gill ventilation frequency (fG) and reduced arterial blood O2 content (CaO2 in both dietary groups, but ED sturgeon exhibited a significantly smaller decrease in CaO2 than did SD animals. Progressive hypoxic exposure (PwO2 decreasing gradually from 20.5 to 3.6 kPa within 45–60 min) led to a significant increase in VO2 at intermediate levels of PwO2 in SD sturgeon that was not seen in ED animals. Furthermore, ED sturgeon showed no significant reduction in arterial plasma pH (pHa) and CaO2 at PwO2 levels that caused significant reductions in these variables in SD sturgeon. ED sturgeon exhibited a smaller increase in plasma lactate level than did SD fish. We suggest that PUFA and/or vitamin E contribute significantly to regulation of metabolism in hypoxia.

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