Measuring the Mitochondrial Ubiquinone (Q) Pool Redox State in Isolated Respiring Mitochondria

The ubiquinone (Q) pool represents a node in the mitochondrial electron transport chain (ETC) onto which the electrons of all respiratory dehydrogenases converge. The redox state of the Q pool correlates closely with the electron flux through the ETC and is thus a parameter of great metabolic value for both the mitochondrial and cellular metabolism. Here, we describe the simultaneous measurement of respiratory rates of isolated mouse heart mitochondria and the redox state of their Q pool using a custom-made combination of a Clark-type oxygen electrode and a Q electrode.