Preparation of brush border membrane vesicles from bovine choroid plexus.

The purpose of this study was to establish a method for preparing brush border membrane vesicles (BBMV) from bovine choroid plexus epithelium. Using the technique of divalent cation precipitation and differential centrifugation, we established and validated a procedure. The specific activity of Na+/K+ ATPase, a specific marker for choroid plexus brush border membranes, was enhanced greater than 14-fold in the final membrane preparation in comparison to its specific activity in the homogenate. The specific activities of marker enzymes for basolateral membranes, lysosomal membranes, and endoplasmic reticulum were enhanced less than fourfold in the final preparation. The presence of intact vesicles was ascertained by electron micrography and studies of osmotic sensitivity using isotopic uptake methods. Sodium-driven proline uptake was demonstrated confirming the presence of functional tightly sealed choroid plexus BBMV.