Seasonal cycles of mitochondrial ADP sensitivity and oxidative capacities in trout oxidative muscle |
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Authors: | H Guderley J St Pierre |
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Institution: | (1) Département de biologie, Université Laval, Québec, PQ G1K 7P4, Canada e-mail: helga.guderley@bio.ulaval.ca, CA |
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Abstract: | Mitochondria from red myotomal muscle of rainbow trout, Oncorhynchus mykiss, showed seasonal cycles of their maximal rates of substrate oxidation (nmol · min−1 mg−1 mitochondrial protein) and their apparent ADP affinity (Kmapp), as well as in the thermal sensitivity of these properties. Increases in the maximal capacity of pyruvate oxidation were
sufficient to compensate for seasonal changes in temperature, except during the winter months when rates at habitat temperature
were depressed relative to other periods. The ADP affinity of isolated mitochondria was highest during cold months. Thus,
the Kmapp for ADP at habitat temperature showed less seasonal variation than the ADP Kmapp at a given temperature. A loss in ADP affinity with decreasing temperature occurred through much of the year, and only was
definitively suppressed in December and July. Both the ADP affinity and the maximal oxidative capacities of muscle mitochondria
seem to be regulated parameters.
Accepted: 10 June 1999 |
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Keywords: | Mitochondria Temperature Muscle Seasonal acclimatisation Trout |
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