the most important factor determining threshold electrotonus is membrane potential, so threshold electrotonus can also be used as an index of membrane potential. furthermore, it can be used to identify characteristics of significant medical conditions through comparing the effects of those conditions on threshold potential with the effects viewed experimentally. for example, ischemia and depolarization cause the same "fanning in" effect of the electrotonus waveforms. this observation leads to the conclusion that ischemia may result from over-activation of potassium channels.