The Hot Mitochondrion Paradox: Reconciling Theory and Experiment

Experiments by Chretien and co-workers suggest that mitochondria are 10oC hotter than their surroundings. Steady-state theoretical estimates place this difference at a maximum of 10^-5 oC. This million-fold disagreement may be called the hot mitochondrion paradox. It is suggested that every proton translocated via ATP synthase sparks a picosecond temperature-difference spike of the order of magnitude measured by Chretien et al. Time-averaging of these spikes recovers the theoretical value. Further, a temporal and spatial superposition of the fluorescence intensity of a very large number of molecular thermometer molecules in the sample can give the appearance of a steady signal. The inner mitochondrial membrane appears to be flanked by temperature differences fluctuating in time and along the membrane s surface, with hot and cold spots as ultrashort temperature spikes.