Anesthetics produce differential actions on the discharge activity of a single neuron

The effects of 26 anesthetic agents were studied on the rhythmical discharge activity of a single isolated neuron (crayfish stretch receptor). Many of these agents produced concentration-dependent biphasic responses (excitation and depression), and some also induced altered discharge patterns (burst activity). The dominant effect of a few of the anesthetics was excitation (e.g. alphaxolone); depression (e.g. decanol); or burst activity (e.g. benzocaine). A correlation was found to exist between equieffective concentrations in the perfusate and membrane/buffer partition coefficients; however, this general phenomenon does not provide an explanation for the biphasic or differential responses. These results demonstrate that selective interactions occur at the level of the single neuron, and suggest the existence of recognition sites in neuronal membranes which can discriminate structural differences of anesthetics.