Lack of cytochemically detectable cholesterol in rabbit vena cava endothelial plasma membrane

The response of rabbit vascular endothelial plasma membranes to the cholesterol-binding agents filipin and tomatin was investigated by freeze-fracture electron microscopy. In both single and double labelling experiments, the endothelial plasma membranes of the posterior vena cava were remarkably resistant to the agents compared with the endothelial plasma membranes of other vessels (aorta, pulmonary artery, and pulmonary and cardiac capillaries). This suggests that vena cava endothelium differs markedly from other endothelia, either by having exceptionally low cholesterol levels in its plasma membranes, or with respect to other membrane properties that influence the reaction to filipin and tomatin.