Effects of extrinsic electric current on the cyprinid fish EIRG (S-potential).

1) For the purpose of clarifying the nature of the so-called cone action potential (S-potential), some electric properties of the membrane, from inside which this action potential was recorded, was investigated by means of doublebarrelled microelectrode technique.2) Neither depolarizing nor hyperpolarizing current passage gave influence to the original response in its amplitude and configuration. In other words, S-potential did not have an equilibrium potential.3) While the values of effective resistance were widely distributed in a range from below 200 KΩ to over 3 MΩ, there appeared to be some difference in their distribution between L-and RG-elements. The effective resistance was not changed during activity and was independent of the change in amplitude of the response produced by the change in the intensity of illumination.4) Based on the above results, it was fully discussed whether the nature of S-potential is of intra-or extracellular.