Microelectrode Studies on the Membrane Properties of Isolated Mitochondria

The membrane potentials and resistances of isolated Drosophila mitochondria were measured after impalement with piezoelectric-driven microelectrodes. The potential is approximately +10 mv (positive inside), and the membrane resistance is approximately 2Omega.cm(2) under state 4 conditions. Experiments involving changes in external osmolality at constant ionic strength have suggested that the measured potential is across the mitochondrial semipermeable membrane. The mitochondria generally collapse seconds after impalement. In cases of successive impalements, potential and resistance values show slight decreases from the initial impalements.