Energy turnover in the normoxic and anoxic turtle heart.
We examined the possibility that the heart of the tuttle 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 degrees C we find that turtle hearts perfused with anoxic saline do not show a particularly outstanding ability to produce ATP anaerobically. Furthermore, at 15 degrees C anoxia reduced the ATP turnover rate to 50% of the normoxic rate. At 5 degrees 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 degrees C reduced the basal metabolic rate of the tuttle 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.
Arthur
P G
PG
Department of Zoology, University of British Columbia, Vancouver, Canada. parthur@cyllene.uva.edu.ad
Franklin
C E
CE
Cousins
K L
KL
Thorarensen
H
H
Hochachka
P W
PW
Farrell
A P
AP
D000255:Adenosine Triphosphate / Q000378:metabolism; D015308:Anaerobic Threshold / Q000502:physiology; D000818:Animals; D004734:Energy Metabolism; D006019:Glycolysis / Q000502:physiology; D000860:Hypoxia / Q000378:metabolism*; D019344:Lactic Acid / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism*; D010101:Oxygen Consumption; D005082:Physical Exertion / Q000502:physiology; D013696:Temperature; D014426:Turtles
D019344:Lactic Acid; D000255:Adenosine Triphosphate