Magnesium transport by mitochondria

The pathways for the uptake and extrusion of Mg²⁺ by mitochondria are not well defined. the present evidence suggests that uptake occurs by nonspecific diffusive pathways in response to elevated membrane potential. There is disagreement as to some of the properties of Mg²⁺ efflux from mitochondria, but the reaction resembles K⁺ efflux in many ways and may occur in exchange for H⁺. Matrix free magnesium ion concentration, Mg²⁺], can be measured using fluorescent probes and is set very close to cytosol Mg²⁺] by a balance between influx and efflux and by the availability of ligands, such as P_i. There are indications that matrix Mg²⁺] may be under hormonal control and that it contributes to the regulation of mitochondrial metabolism and transport reactions.