Severe Problems of the Voltage‐Clamp Method in Concurrent Monitoring of Membrane Potentials

Abstract

In nerve cells, the concurrent monitoring of multipoint on the axon has been conducted based on the voltage‐clamp method using two long parallel electrodes inside and outside the axon. As the respective membrane potentials have been evaluated by considering the clamping potential, the local current, and the conductance, the membrane potentials were not actually evaluated. We directly measured the actual membrane potentials and local currents of the respective cells using a nerve‐model‐system comprising some liquid‐membrane cells. It is proved that the action potential propagation is artificially facilitated or prevented by both the external electric generator and two long electrodes.

Elucidation of Rapid Synchronization on Electric Discharge by Use of Model Cell Systems Mimicking Electric Organs of Electric Eel

“…4,12,15 In the present study, two types of electrochemical cells mimicking the functions of K + and Na + channels, respectively, were constructed by combination of a liquid-membrane (LM) and two aqueous phases (W1 and W2). [25][26][27] A porous polytetrafluoroethylene resin (PTFE) membrane filter T300A025A (diameter: 25 mm, pore size: 3.0 µm, thickness: 75 µm) was purchased from Toyo Roshi Kaisya, Ltd., and was used to stabilize the NB solution in the filter as the liquid membrane. Respective cells were named K h , K c , and Na cells.…”

“…Recently, a model system combining multiple liquid-membrane cells has been applied to examine the propagation mechanism of electrical signals within one cell or among multiple cells by the author's group. [18][19][20][21][22][23][24][25][26][27][28] It was proved that propagation of the membrane potential was caused by locally circulating currents in the model neuron composed of several liquid-membrane cells mimicking Na + and K + channels. [24][25][26] The author's group has pointed out that there are serious problems in conventional concepts of nerve conduction as follows.…”

“…[18][19][20][21][22][23][24][25][26][27][28] It was proved that propagation of the membrane potential was caused by locally circulating currents in the model neuron composed of several liquid-membrane cells mimicking Na + and K + channels. [24][25][26] The author's group has pointed out that there are serious problems in conventional concepts of nerve conduction as follows. First, it is not sufficient to consider the influence of neuronal firing at postsynaptic membrane on the propagation of action potential (directional propagation and potential profile along the axon).…”