[Molecular aspects of bioelectrogenesis]

Abstract

The action potential is a dissipative process producing entropy and using free energy. This is well demonstrated by: 1) the evolution of the Na conductance under voltage clamping conditions, 2) the microcalorimetric measurements, 3) the analysis of heat evolution during the conductance changes. The most appropriate explanation must involve an exogenous energy source since the energy dissipated by the ionic flows or even the applied stimulus depolarization are far too small to account for the overall energy balance. Thiamine triphosphate is a likely candidate as specific operating substance. The more so, since it is specifically hydrolyzed by a triphosphatase the activity of which is modulated by various anions. It is therefore suggested that the control of the Cl-permeability, a process requiring the hydrolysis of thiamine triphosphate, is the key to our understanding of the energetics of the action potential.