Preparation of glial plasma membrane from a cell fraction enriched in astrocytes

A technique for obtaining glial plasma membrane has been developed, starting with a bulk-prepared glial cell-enriched fraction from rabbit cerebral cortex. The astrocytic-enriched fraction was hand-homogenized in isotonic sucrose media, and the crude membrane fraction sedimented at 3,000g. The isolation of a membrane-enriched fraction was accomplished with sucrose density gradient centrifugation. The plasma membrane fraction was collected at the interphase between 31.5% and 25.5% sucrose. Enzymatic and electron-microscopical analyses indicated a 4-7-fold enrichment in plasma membrane, and a 15-20% contamination with microsomal and mitochondrial material. Some multilaminar membrane structures were also seen in the fraction.