membrane potential measurement method All living cells maintain a resting membrane potential, which is the difference in voltage between the interior and exterior of the cell. Electrically active cells, such as neurons, muscle and endocrine cells undergo changes in membrane potential due to depolarization and hyperpolarization as a result of opening and closing of ion channels. Action potentials are large and rapid changes in membrane potential which are generated as a result of a large depolarization event. In neurons, action potentials are used to transmit signals across neurons, while in muscle and endocrine cells, they lead to intracellular events, such as muscle contraction and hormone release, respectively. In addition, mitochondria possess a trans-membrane potential as a result of their respiratory function. Membrane potential can be measured either by using electrophysiological techniques or by staining with dyes whose binding is dependent on the membrane potential. assay design method