Galli 2012 J Therm Biol
|Galli GL, Richards JG (2012) The effect of temperature on mitochondrial respiration in permeabilized cardiac fibers from the freshwater turtle, Trachemys scripta. J Ther Bio 37:195–200.|
Abstract: Ectothermic animals regularly experience fluctuations in body temperature, which have profound effects on biochemical and metabolic processes. To cope with cold environments, the freshwater turtle, Trachemys scripta, exhibits inverse thermal compensation, where physiological processes exhibit exaggerated Q10 effects and are actively downregulated to limit energy requirements. The present study aimed to identify potential sites of temperature sensitivity in mitochondria from the turtle heart. The effect of acute temperature change on ADP sensitivity and respiratory flux through different components of the electron transport chain (Complexes I, II and IV) was analysed in permeabilized cardiac fibers from the turtle ventricle. An acute decrease in temperature significantly reduced the acceptor control ratio and maximum respiration rate through all complexes of the electron transport chain. Calculated Q10 values for across the three experimental temperatures tested (5, 13 and 21 °C) were in the range of 1.19–3.65, and although there was a tendency for exaggerated Q10 values in the lower temperature range (5–13 °C), there were no significant differences in Q10 between any temperatures or complexes examined. These results suggest the large-scale reductions in turtle cardiac function and high Q10 values at acutely low temperatures are likely due to a reduction in energy demand (contractile function), rather than supply (mitochondrial respiration).
• Keywords: Red eared slider (Trachemys scripta) turtles, Acceptor control ratio, Maximum respiration rate, Electron transport chain, Q10
Labels: MiParea: Respiration, Comparative MiP;environmental MiP
Organism: Reptiles Tissue;cell: Heart Preparation: Permeabilized tissue Enzyme: Complex I, Complex II;succinate dehydrogenase, Complex IV;cytochrome c oxidase Regulation: ADP, Temperature Coupling state: OXPHOS