Anesthetics produce differential actions on membrane responses of the crayfish stretch receptor neuron

The actions of ethanol, halothane and pentobarbital on the membrane electrical properties and synaptic transmission of isolated crayfish stretch receptor neurons were studied to determine possible sites of action contributing to differential effects previously described on physiological discharge activity. The three agents depressed GABA-mediated transmission and altered postsynaptic membrane electrical properties. Both pre- and postsynaptic sites of action appeared to contribute to the anesthetic-induced alteration of neuronal function. The agents studied produced different, concentration-dependent, membrane effects which included biphasic actions on membrane resistance and spike threshold. The results suggest that multiple-sites of action are involved and different anesthetics may not act via the same mechanism(s) at these sites.