The influence of dietary fatty acid composition on the respiratory and cardiovascular physiology of Adriatic sturgeon (Acipenser naccarii): a review

Summary This paper reviews evidence that the fatty acid composition of dietary lipids influences the respiratory and cardiovascular physiology of Adriatic sturgeon (Acipenser naccarii) and, thereby, their tolerance of the stress of hypoxia. Sturgeon fed a commercial diet enriched in fish oil (menhaden oil as 15% of dry feed weight), with an elevated content of highly unsaturated fatty acids of the ω3 series (ω3 HUFA), had a significantly lower standard metabolic rate (SMR) and routine oxygen consumption (Mo2) than those fed a diet enriched with the same quantity of hydrogenated coconut oil, with an elevated content of saturated fatty acids (SFA). Both groups grew equally well. As a result of this difference in aerobic metabolism, sturgeon fed the ω3 HUFA and SFA responded differently when exposed to hypoxic challenges, those fed ω3 HUFA appearing more hypoxia-tolerant. Sturgeon fed ω3 HUFA exhibited no significant reflex hyperventilation when exposed to mild, moderate or deep hypoxia (30 min at water O2 partial pressures of 10.8, 6.6 and 4.6 kPa, respectively), no hypoxic depression of spontaneous activity during 3h in mild hypoxia, and no depression of Mo2 during 3h in moderate hypoxia, unlike sturgeon fed SFA. The diets also influenced the performance of isolated hearts in vitro. Hearts from fish fed ω3 HUFA maintained maximum in vitro cardiac power output unchanged when oxygen supply was reduced (O2 content from 2.3 to 0.7 vol.%), unlike hearts from sturgeon fed SFA. Overall, the results indicate that dietary fatty acid composition can influence tolerance of hypoxia in sturgeon, through effects on SMR. When compared to sturgeon fed SFA, those fed ω3 HUFA had lower SMR and were more tolerant of hypoxia, with effects both on the whole animal and on the isolated heart.