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  • 1
    Electronic Resource
    Electronic Resource
    Effects of exercise-training on cardiac performance and muscle enzymes in rainbow trout,Oncorhynchus mykiss (1991)
    Springer
    Fish physiology and biochemistry 9 (1991), S. 303-312 
    Details
    ISSN: 1573-5168
    Keywords: exercise-training ; heart ; adrenaline ; stroke volume ; energy metabolism ; flux capacity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Rainbow trout,Oncorhynchus mykiss, were exercise-trained for 18 hours per day over 28 days at water velocities up to 60% of their measured Ucrit. Anin situ perfused heart preparation was used to compare maximum cardiac performance between control and trained fish. Trained fish had a larger stroke volume at a given filling pressure, as well as an 18% higher cardiac output and a 25% greater maximum power output. These observations indicate that exercise training in rainbow trout improved maximum cardiac performance. Adrenaline produced positive inotropic and chronotropic effects on the perfused heart, but exercise training did not alter these stimulatory effects. Maximal activities of citrate synthase (CS), B-hydroxyacyl CoA dehydrogenase (HOAD), glutamate dehydrogenase (GDH) and carnitine palmitoyl transferase (CPT) were measured in cardiac and skeletal muscles. CS, HOAD and GDH increased in red and white skeletal muscle as a result of training. Training also increased GDH activity in the endocardium and epicardium, and increased HOAD in the epicardium. While the training regime did not result in a statistically significant increase in Ucrit and produced a decrease in the condition factor of the fish, other training effects were clearly evident. Furthermore, significant correlations were observed between Ucrit and the maximal activities of GDH and HOAD.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02265151
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of temperature and temperature acclimation on the ryanodine sensitivity of the trout myocardium (1994)
    Springer
    Journal of comparative physiology 164 (1994), S. 438-443 
    Details
    ISSN: 1432-136X
    Keywords: Ryanodine ; Sarcoplasmic reticulum ; Temperature ; Acclimation ; Trout,Oncorhynchus mykiss
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The influence of acute temperature change and temperature acclimation on the sensitivity of contracture development to ryanodine were examined in the rainbow trout myocardium using two preparations: in vitro isolated ventricular strips and in situ working perfused hearts. Ryanodine effects in vitro were dependent on test temperature (8 and 18 °C), pacing frequency (0.2–1.5 Hz) and acclimation temperature (8 and 18 °C). At a pacing frequency of 0.2 Hz and a test temperature of 18 °C, ryanodine depressed isometric tension development in ventricular strips both from trout acclimated to 8 and 18 °C but the decrease was significantly greater in strips from 8 °C-acclimated trout. No ryanodine effect was observed in either acclimation group at a test temperature of 8°C. The effect of ryanodine in vitro was reduced or lost at pacing frequencies greater than 0.2 Hz and at 0.6 Hz ryanodine depressed tension development at 18 °C only in strips from 8 °C-acclimated trout. Ryanodine did not affect tension development at stimulation rates above 0.6 Hz in any test group. Likewise, ryanodine did not significantly impair cardiac performance of in situ working perfused heart preparations which operated at intrinsic beat frequencies in excess of 0.6 Hz. These results suggest that the sarcoplamic reticulum calcium release channel of the trout myocardium is expressed but is not functionally involved in beat-to-beat regulation of contractility at either (1) low temperature (8 °C), or (2) at routine physiological heart rate (〉0.6 Hz). However, under conditions in which involvement of the sarcoplasmic reticulum is observed (18 °C and a heart rate 〈 0.6 Hz), prior acclimation to low temperature results in either a greater capacity of the sarcoplasmic reticulum to store releasable calcium or an increase in the amount of calcium that is in releasable form.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00714580
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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