Abstract

To examine cardiorespiratory plasticity, cardiovascular function, oxygen consumption, oxygen delivery and osmotic balance were measured at velocities up to critical swimming speed (U-crit) in seawater-adapted chinook salmon. We used two groups of fish. The control group had swum continuously for 4 months at a low intensity (0.5BLs(-1)) and the other was given a high-intensity training regimen (a U-crit swim test on alternate days) over the same period of time. Compared with available data for other salmonid species, the control group had a higher maximum oxygen consumption (over dot(O2max); 244 mu mol O(2)min(-1)kg(-1)), cardiac output (over dot(max); 65 ml min(-1) kg(-1)) and blood oxygen content (Ca-O2; 15mlO(2)dl(-1)). Exercise training caused a 50% increase in over dot(O2max) without changing either U-crit or Ca-O2, even though there were small but significant increases in hematocrit, hemoglobin concentration and relative ventricular mass. During swimming, however, exercise-trained fish experienced a smaller decrease in body mass and muscle moisture, a smaller increase in plasma osmolality, and reduced venous oxygen stores compared with control fish. Consequently, exercise training apparently diminished the osmo-respiratory compromise, but improved oxygen extraction at the tissues. We conclude that the training-induced increase in over dot(O2max) provided benefits to systems other than the locomotory system, such as osmoregulation, enabling trained fish to better multitask physiological functions while swimming. Furthermore, because a good interspecific correlation exists between over dot(O2max) and arterial oxygen supply (over dot(O2max); r(2)=0.99) among temperate fish species, it is likely that Cao(2) and over dot(max) are principal loci for cardiorespiratory evolutionary adaptation but not for intraspecific cardiorepiratory plasticity as revealed by high intensity exercise training.

Keywords

salmon; cardiac output; heart rate; oxygen consumption; plasma osmolality; oxygen transport; swimming; exercise training; osmo-respiratory compromise; Oncorhynchus tshawytscha

Published in

Journal of Experimental Biology
2001, Volume: 204, number: 16, pages: 2861-2872
Publisher: COMPANY OF BIOLOGISTS LTD

UKÄ Subject classification

Fish and Aquacultural Science
Zoology


Permanent link to this page (URI)

https://res.slu.se/id/publ/80482