Preparative resolution and identification of synaptic components of rat neocortex

Abstract

Abstract A varity of density gradient centrifugation techniques have been used with varying degrees of success, for the preparative resolution of pinched off nerve endings, i.e. “synaptosomes,” and synaptic components from brain homogenates. The physics of such gradients was critically considered from the standpoint of improving the degree of resolution of particulate classes and preserving morphological integrity. A procedure, using continuous linear Ficoll gradients, is presented which yields improved particulate resolution with good preservation of ultrastructural morphology. Further purification of the membraneous fraction yielded relatively high purity preparations of PSM particulates. The PSM particulates were identified as dissociated postsynaptic membranes by three kinds of electron microscope studies. Broad field electron micrographs, which permit assessment of fraction homogeneity, are presented for all fractions.