High temperature impairs mitochondrial function in rainbow trout cardiac mitochondria

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