Elucidation of Rapid Synchronization on Electric Discharge by Use of Model Cell Systems Mimicking Electric Organs of Electric Eel (Supporting Information)

The electric organ of a typical electric fish was artificially constructed by use of a model-cell system combining liquid-membrane cells mimicking the function of K+ and voltage-gated Na+ channels. The relation between the power generation of the electric organ and the rapid synchronization was investigated using the external electric stimulus. As for a model electrocyte, only a K+-channel-mimicking cell was set on the head side and both K+-channel and voltage-gated Na+-channel mimicking cells were placed on the caudal side. The potential difference between one and another side through the electrocyte changed from 0 V to about 0.15 V after the external electric stimulus was applied. In the firing state, the electric current due to the transfer of K+ and Na+ flowed through the model electrocyte. When multiple model electrocytes were in series, the simultaneous ignitions by opening of voltage-gated Na+ channels generate a large voltage through the electrocyte aggregates. In this case, the total voltage was the sum of the potential differences of the respective electrocytes. When several model electrocytes were in parallel, the total current was the sum of the currents of all electrocytes. The rapid synchronization of the electric organ of the electric eel (0.5 ms level) seems to be caused by circulating leak currents among neighboring cells through neural and vascular networks.