Changes in the mitochondrial surface potential during cuprizone-induced formation of megamitochondria.

The formation of megamitochondria upon treatment of mice with cuprizone was studied in relation to the surface potential of mitochondria. The latter was monitored by binding of 8-anilino-1-naphthalene sulphonate to membranes, by kinetics of monoamine oxidase and by free-flow electrophoresis of the particles. It was found that the surface potential of megamitochondria was by about 20 mV less negative than that of normal mitochondria whereas no change of the surface potential upon cuprizone treatment was observed in microsomes. It is suggested that a partial neutralization of the negative surface charge of mitochondrial membranes may promote fusion or inhibit division of mitochondria, thus resulting in formation of giant structures.