[29] Mitochondrial membrane potential monitored by JC-1 dye

This chapter focuses on the mitochondrial membrane potential monitored by JC-1 dye. It uses JC-1 to investigate the remaining questions about mitochondrial membrane potential in living cells, including the component of the electrochemical gradient that is responsible for the formation of J-aggregates, the study of all mitochondria in the same cell does have a similar membrane potential, and the study of the variation of membrane potential within a given mitochondrion. The chapter discusses the JC-1 uptake by isolated mitochondria. In these studies using isolated cardiac mitochondria, JC-1 monomers were taken up into the mitochondrial matrix as a result of changes in the membrane potential of energized and coupled mitochondria. JC-1 uptake by mitochondria in living cells is presented. For the majority of cell types and cell lines examined, it is possible that all mitochondria in the same cell do not maintain the same membrane potential.