Plasma membrane coating with cationic silica particles and osmotic shock alters the morphology of bovine aortic endothelial cells

We have used a published method of membrane preparation based on the precoa ting of the apical membrane of aortic endothelial cells with cationic silic a microbeads (with or without polyacrylic acid) in combination with an osmo tic shock and mechanical shearing to isolate the apical from the basal plas ma membranes of these cells, in vitro. After labeling of the plasma membran e of adherent endothelial cells with a fluorescent derivative of phosphatid ylcholine and by using laser confocal fluorescence scanning microscopy, we found that this method of membrane isolation rapidly induced invaginations of the basal plasma membrane ro an extent which makes this method unsuitabl e for further membrane lipid analysis. Morphological analysis of the cells and fluorescence recovery after photobleaching experiments on the plasma me mbranes were performed at each step of the purification procedure and showe d that only hypotonic shock and mechanical shearing of the cells enabled th e basal plasma membranes to be purified without significant morphological c hanges. (C) 2000 Elsevier Science B.V. All rights reserved.