Mechanism of Na+ ions contribution to the generation and maintenance of a high inner membrane potential in mitochondria

Abstract

A recent revision of the chemiosmotic theory was reported by Hernansanz-Agustín and coauthors as a discovery that a Na⁺ gradient across the mitochondrial inner membrane equates with the H⁺ gradient and contributes up to half of the inner membrane potential, without an explanation of the possible underlying mechanism. Based on the experimental data of these and other authors, and performed biophysical estimations, I propose a mechanism by which both the reported fast-acting Na⁺/H⁺ exchanger, associated with the complex I of the respiratory chain, and Na⁺ electrodiffusion in the intracristae space and the matrix allow maintenance of a high membrane potential.