[Incorporation and release of cholesterol from plasma membranes of hepatocytes and Zajdela hepatoma cells].

Molar ratio of cholesterol/phospholipids was decreased in Zajdela hepatoma cell membranes as compared with rat normal hepatocytes. Microviscosity of lipid bilayer was increased in membranes of normal and malignant cells, while the activity of Na+, K+-ATPase and 5'-nucleotidase was decreased during introduction of cholesterol into the cell membranes. As compared with control groups the duration of life was increased in the group of animals implanted with Zajdela hepatoma cells modified by cholesterol. The data obtained suggest that an increase in microviscosity of membranes in tumoral cells, enriched with cholesterol, might inhibit their mitotic divisions.