Thermal sensitivity of oxidative phosphorylation in rat heart mitochondria: Does pyruvate dehydrogenase dictate the response to temperature?

To identify the most temperature-sensitive steps in the energy production pathways, we measured the thermal sensitivity of mitochondrial oxidative phosphorylation (OXPHOS), as well as that of the individual steps in this process in rat heart mitochondria. OXPHOS measured in the presence of pyruvate+malate as substrates have an unusually high thermal sensitivity between 5 and 15°C. Furthermore, the thermal sensitivity of OXPHOS correlates with the thermal sensitivity of pyruvate dehydrogenase between 5 and 35°C. Pyruvate dehydrogenase is a potential control point for pyruvate-supported mitochondrial respiration below physiological temperature in rat heart.