A SIMPLE METHOD FOR RECORDING SINGLE-CHANNEL ACTIVITY FROM SYNAPTIC PLASMA-MEMBRANES

Due to the small size of most nerve terminals, the ion channels which underlie presynaptic currents are usually inaccessible to investigatio n by conventional electrophysiological techniques. Here we describe a simple method for obtaining single-channel recordings from synaptic pl asma membranes that does not require exposure of the native membranes to exogenous lipids or fusogens. To illustrate the method, we have rec orded single-channel activity from rat cerebrocortical synaptosomal me mbranes. Under conditions designed to isolate calcium-independent curr ents, we describe three channel types that are most commonly observed.