ARE FISH PRIMARILY STROKE VOLUME-MODULATORS? NOT ACCORDING TO CENTRARCHIDS
In most animals, physical or chemical stressors usually elicit an increase in metabolic rate and consequently an increase in cardiac output and one or both of its components, heart rate and stroke volume. While mammals and birds primarily increase cardiac output through the elevation of heart rate (...
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| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.611.504 http://www-heb.pac.dfo-mpo.gc.ca/congress/2002/Cardiovasc/Schreer.pdf |
| Summary: | In most animals, physical or chemical stressors usually elicit an increase in metabolic rate and consequently an increase in cardiac output and one or both of its components, heart rate and stroke volume. While mammals and birds primarily increase cardiac output through the elevation of heart rate (frequency modulation), fish are generally thought to increase cardiac output principally through changes in stroke volume (volume modulation). It has even been suggested that among vertebrates there is an evolutionary trend from volume-modulated to frequency-modulated cardiac output. Within fish, only a few species have been regarded as frequency-modulators including the highly active tuna and the Antarctic nototheniids. In an effort to expand our comprehension of cardiac function in fish, we collected data on several species from two common families, Salmonidae and Centrarchidae, under various conditions. Our preliminary findings indicate that frequency modulation is more prevalent than previously thought especially among centrarchids. 80 |
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