[Determination of electrical characteristics of synaptosomal membranes of the brain]

A correct method for evaluating the potential differences across plasma membranes of synaptosomes from the brain is presented. It takes into consideration the multicompartment synaptosome organization and is based on the accumulation of the radioactive permeant cation [3H]tetraphenylphosphonium. It is shown that upon potassium depolarization of the synaptosomes to about -5 mv there is a sharp decrease in the ion selectivity of the synaptic membranes.