Energy Turnover in the Normoxic and Anoxic Turtle Heart

• Published in: Comparative biochemistry and physiology. A, Comparative physiology Comparative physiology, 1997-05, Vol.117 (1), p.121-126
• Main Authors: Arthur, Peter G, Franklin, Craig E, Cousins, K.L, Thorarensen, H, Hochachka, P.W, Farrell, A.P
• Format: Article
• Language: English
• Subjects: Adenosine Triphosphate - metabolism; Anaerobic Threshold - physiology; Animals; anoxia; ATP; cardiac; cardiac output; Chrysemys scripta; Energy Metabolism; Freshwater; glycolysis; Glycolysis - physiology; heart rate; Hypoxia; Hypoxia - metabolism; lactate; Lactic Acid - metabolism; metabolic rate; Myocardium - metabolism; Oxygen Consumption; Physical Exertion - physiology; Space life sciences; Temperature; Turtles
• ISSN: 0300-9629; 1096-4940
• DOI: 10.1016/S0300-9629(96)00283-6

We examined the possibility that the heart of the turtle Chrysemys scripta is an exceptional anaerobic performer, by measuring myocardial power output, lactate output, and estimated ATP turnover in perfused heart preparations. Over a range of myocardial power outputs at 5 and 15°C we find that turtle hearts perfused with anoxic saline do not show a particularly outstanding ability to produce ATP anaerobically. Furthermore, at 15°C anoxia reduced the ATP turnover rate to 50% of the normoxic rate. At 5°C the anoxia-induced depression of ATP turnover was even more pronounced, being 4-fold lower than the normoxic rate. In addition, anoxia at 5°C reduced the basal metabolic rate of the turtle heart. We conclude that long-term cardiac tolerance of hypoxia in this species is more likely related to metabolic depression rather than to an exceptional anaerobic performance.