The mean conductance and open-time of the acetylcholine receptor channels can be independently modified by some anesthetic and convulsant ethers

The effects of two anesthetic ethers methoxyflurane and diethyl ether (ether), and one convulsant ether, fluothyl, were examined on miniature end-plate currents and on end-plate current fluctuations at the frog neuromuscular junction. Either methoxyflurane or fluothyl was found to reduce the amplitude and the half-decay time of the miniature end-plate currents. When the concentration of methoxyflurane was raised from 10^-4 to 5.10^-4 M its effect on the miniature end-plate current amplitude was increased but that on the half-decay time remained unaltered. The effect of ether on the miniature end-plate current was dose-dependent: at 10^-3 M it reduced the half-decay time without affecting the amplitude, whereas at 10^-2 M it increased the half-decay time and decreased the amplitude. Analysis of end-plate current fluctuations revealed that the effects of methoxyflurane (5.10^-4 M) and ether (10^-2 M) on the mean conductance and open-time of the acetylcholine receptor channels were comparable to their effects on the amplitude and the half-decay time of the miniature end-plate current. It is concluded that the effect of such structurally 'non-specific' drugs comprises a combination of discrete and distinguishable events which are specific and dose-dependent for each of the agents used.