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High temperature impairs mitochondrial function in rainbow trout cardiac mitochondria

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DOI

Mitochondria provide cellular energy through oxidative phosphorylation, and thus temperature-induced constraints on mitochondrial function may be crucial to animal aerobic scope and thermal tolerance. Here, we report the effect of temperature in the range 5-30 degrees C on respiration rates of isolated cardiac mitochondria from rainbow trout (Oncorhynchus mykiss) studied by high-resolution respirometry and spectrophotometric enzyme activity assays. Arrhenius breakpoint temperature analysis indicated that mitochondrial respiration rates under phosphorylating and fully uncoupled conditions increased exponentially up to 20 degrees C, but stopped increasing at higher temperatures. In contrast, respiration rates measured under non-phosphorylating leak conditions continued to increase up to 30 degrees C. The decrease in the ratio between phosphorylating and uncoupled respiration at high temperature indicated that phosphorylation was gradually impaired with increasing temperature, possibly because of the steadily increasing proton leak across the membrane. In addition, we found that complex I (NADH dehydrogenase) activity decreased above 20 degrees C, similarly to mitochondrial respiration, and that complex I was unstable in the presence of detergents, suggesting that it may be particularly sensitive to changes in its interaction with membrane phospholipids. In contrast, complex II (succinate dehydrogenase) maintained activity at temperatures above 20 degrees C, although succinate oxidation was insufficient to compensate for the loss of complex I activity in intact mitochondria. Together, these results indicate that the temperature-induced decrease in cardiac mitochondrial function coincides with the temperature at which trout aerobic scope peaks, and is largely due to impaired phosphorylation and complex I activity.

Original languageEnglish
Article numberjeb242382
JournalJournal of Experimental Biology
Volume224
Issue9
Number of pages7
ISSN0022-0949
DOIs
Publication statusPublished - May 2021

Bibliographical note

Publisher Copyright:
© 2021. Published by The Company of Biologists Ltd.

    Research areas

  • Complex I, Fish, Heart, Mitochondria, Respiration, Temperature, THERMAL TOLERANCE, OXIDATIVE CAPACITIES, ONCORHYNCHUS-MYKISS, HEART-MITOCHONDRIA, SENSITIVITY, PHOSPHOLIPIDS, ACCLIMATION, RESPIRATION, MECHANISM, EVOLUTION

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