  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.
