[8] Calcium ion transport in mitochondria

This chapter discusses the calcium ion transport in mitochondria. Mitochondria are organelles capable of accumulating and releasing calcium ion (Ca2+) in the cell. Calcium channels and pumps in the plasma membrane determine the overall cellular Ca2+ content. Mammalian mitochondria accumulate Ca2+ mainly by an electrogenic mechanism that drives Ca2+ into the matrix at the expense of the membrane potential generated by the respiration or hydrolysis of Adenosine triphosphate (ATP) while efflux of Ca2+ occurs mainly by other electroneutral mechanisms. Under physiological conditions, the distribution of Ca2+ between cytosol and mitochondria is, thus, influenced by the kinetic properties of the influx and efflux mechanisms. Increase in permeability is correlated with the transition of an increasing proportion of the mitochondrial population from an aggregated to an orthodox configuration.