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First published online January 12, 2004
Journal of Experimental Biology 207, 655-665 (2004)
Published by The Company of Biologists 2004
doi: 10.1242/jeb.00791

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Effects of temperature and anoxia upon the performance of in situ perfused trout hearts

Johannes Overgaard^1,2,*, Jonathan A. W. Stecyk², Hans Gesser¹, Tobias Wang¹ and Anthony P. Farrell²

¹ Department of Zoophysiology, Institute of Biological Sciences, University of Aarhus, Denmark
² Department of Biological Sciences, Simon Fraser University, British Columbia, Canada

View larger version (13K): [in a new window]   Fig. 1. Graphical presentation of the experimental protocols used to examine cardiac performance in oxygenated and anoxic in situ perfused trout hearts. Output pressure (Pout) is represented by the solid line, and the two maximal performance tests are shown as the progressive increases in Pout. The anoxic exposure is shown with grey bars. During both routine oxygenated and anoxic conditions, Pin was adjusted to as much as 0.25 kPa to maintain cardiac flow rate () at 12, 16, 20 or 24 ml min-1 kg-1 at 5, 10, 15 and 18°C, respectively. Arrows indicate samples for lactate measurements of the perfusate.

View larger version (22K): [in a new window]   Fig. 2. Routine cardiac performance before, during and after the anoxic period as a function of time. Representative measurements were taken; (1) before maxtest1; (2) 0, 5, 10, 15 and 20 min into the anoxic test; and 3) before maxtest2. (A) Input pressure was adjusted in an attempt to maintain flow at 12, 16, 20 or 24 ml min-1 kg-1 for 5, 10, 15 and 18°C hearts (see text for further explanation). (B) Power output. (C) Heart rate. (D) Stroke volume. (E) Cardiac output. Letters indicate significant changes within each group during anoxia relative to values at the onset of anoxia: bdifferences for hypoxic hearts at 5°C, chypoxic hearts at 10°C, dhypoxic hearts at 15°C and ehypoxic hearts at 18°C.

View larger version (26K): [in a new window]   Fig. 3. Maximal performance of in situ trout hearts measured before and after recovery from 20 min of anoxia. (A-D) Line plots of cardiovascular variables before (filled symbols) and after (open symbols) recovery from 20 min anoxia. (A) Cardiac output, (B) power output, (C) stroke volume, (D) heart rate. (E-H) Recovery of cardiac output, power output, stroke volume and heart rate after anoxia, expressed as the second maxtest relative to the first maxtest. Significant differences (P<0.05) between the initial and second maxtest are indicated with an asterisk, while dissimilar letters indicate significant differences between the relative recovery of cardiac performance. Control 10°C (1) and (2) indicate measurements taken at the onset and conclusion of the experiment, respectively.

View larger version (17K): [in a new window]   Fig. 4. Activity of the glycolytic enzymes pyruvate kinase (A) and lactate dehydrogenase (B) from rainbow trout measured at 5, 10, 15 and 20°C.

View larger version (20K): [in a new window]   Fig. 5. Lactate efflux from in situ trout hearts during oxygenated control (10°C) and at 5, 10 or 15°C during 20 min of anoxia. Measurements were only included if cardiac output was stable.