Alterations in gangliosides of rat liver cells in hyperlipidemic state

The possibility that liver cell membrane is modified in hyperlipidemic state was studied using nephrotic hyperlipidemic rats. Liver cells of normal and nephrotic rats were isolated and subjected to labeling of cell surface components using lacto-peroxidase catalyzed radioiodination. The labeling of total surface lipids of hepatocytes of nephrotic rats was about five times higher than that of normal ones and was particularly higher in glycosphingolipids. Cultivation of the isolated hepatocytes as primary cultures reduced drastically labeling of surface lipids in liver cells of both nephrotic and normal rats and abolished the differences observed in liver cells of the two types. Determination of cell associated gangliosides, showed that the level in nephrotic rat hepatocytes was only 35% higher than that of normal rats. Yet, in both types of liver cells 24 h cultivation decreased markedly the ganglioside content. However, similar to the effect observed in hyperlipidemic rats, supplementing the culture medium with very low density lipoproteins (VLDL) increased considerably the ganglioside level of cultured hepatocytes. These treatments did not affect the activity of enzymes involved in the synthesis of gangliosides. It is suggested that ganglioside content in liver cell membrane is modulated in the hyper-lipidemic state.