The Hot Mitochondrion Paradox: Reconciling Theory and Experiment

TL;DR

This paper proposes a dynamic model where transient, ultrashort temperature spikes caused by proton translocation events explain the observed high mitochondrial temperatures, reconciling experimental and theoretical estimates.

Contribution

It introduces a novel explanation involving transient temperature spikes and superposition effects to resolve the hot mitochondrion paradox.

Findings

Transient temperature spikes occur with each proton translocation.

Superposition of fluorescence signals creates the appearance of steady high temperature.

The inner mitochondrial membrane has fluctuating hot and cold spots.

Abstract

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.