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https://hdl.handle.net/2440/44421
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Type: | Journal article |
Title: | Changes in cardiac output during swimming and aquatic hypoxia in the air-breathing Pacific tarpon |
Author: | Clark, T. Seymour, R. Christian, K. Wells, R. Baldwin, J. Farrell, A. |
Citation: | Comparative Biochemistry and Physiology Part A: Molecular and Integrative Physiology, 2007; 148(3):562-571 |
Publisher: | Elsevier Science Inc |
Issue Date: | 2007 |
ISSN: | 1095-6433 1531-4332 |
Statement of Responsibility: | T.D. Clark, R.S. Seymour, K. Christian, R.M.G. Wells, J. Baldwin and A.P. Farrell |
Abstract: | Pacific tarpon (Megalops cyprinoides) use a modified gas bladder as an air-breathing organ (ABO). We examined changes in cardiac output (V(b)) associated with increases in air-breathing that accompany exercise and aquatic hypoxia. Juvenile (0.49 kg) and adult (1.21 kg) tarpon were allowed to recover in a swim flume at 27 degrees C after being instrumented with a Doppler flow probe around the ventral aorta to monitor V(b) and with a fibre-optic oxygen sensor in the ABO to monitor air-breathing frequency. Under normoxic conditions and in both juveniles and adults, routine air-breathing frequency was 0.03 breaths min(-1) and V(b) was about 15 mL min(-1) kg(-1). Normoxic exercise (swimming at about 1.1 body lengths s(-1)) increased air-breathing frequency by 8-fold in both groups (reaching 0.23 breaths min(-1)) and increased V(b) by 3-fold for juveniles and 2-fold for adults. Hypoxic exposure (2 kPa O2) at rest increased air-breathing frequency 19-fold (to around 0.53 breaths min(-1)) in both groups, and while V(b) again increased 3-fold in resting juvenile fish, V(b) was unchanged in resting adult fish. Exercise in hypoxia increased air-breathing frequency 35-fold (to 0.95 breaths min(-1)) in comparison with resting normoxic fish. While juvenile fish increased V(b) nearly 2-fold with exercise in hypoxia, adult fish maintained the same V(b) irrespective of exercise state and became agitated in comparison. These results imply that air-breathing during exercise and hypoxia can benefit oxygen delivery, but to differing degrees in juvenile and adult tarpon. We discuss this difference in the context of myocardial oxygen supply. |
Keywords: | Air Sacs Animals Fishes Oxygen Cardiac Output Stroke Volume Aging Heart Rate Respiratory Mechanics Swimming Time Factors Northern Territory Physical Exertion Hypoxia |
DOI: | 10.1016/j.cbpa.2007.07.007 |
Published version: | http://dx.doi.org/10.1016/j.cbpa.2007.07.007 |
Appears in Collections: | Aurora harvest Earth and Environmental Sciences publications |
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