EFFECT OF NICOTINE ON LIPOPROTEIN METABOLISM IN RATS

Nicotine, a major component of cigarette smoke, plays an important rol e in the development of cardiovascular disease and lung cancer in smok ers. The effect of nicotine on lipoprotein metabolism was studied usin g rats as the experimental animal. There was a significant increase in the total cholesterol, phospholipids, and triglycerides as well as th e amount of lipids associated with very low density lipoprotein (VLDL) and low density lipoprotein (LDL) in sera of nicotine-treated rats, T he incorporation of H-3 labeled leucine into the apo B was found to be increased both in the medium and associated cells in the hepatocytes isolated from nicotine-treated rats indicating an increased synthesis and secretion of the apo B containing lipoproteins. This was further c onfirmed by the higher incorporation of C-14 acetate into total and in dividual lipids of LDL and VLDL secreted into the medium as well as th at associated with different lipids in the cell layer. The activity of lipoprotein lipase in extrahepatic tissues and plasma lecithin choles terol acyl transferase activity were significantly lower in nicotine-t reated rats. These results indicate that nicotine exerts hyperlipidemi c effects particularly by increasing the synthesis and secretion of tr iglyceride-rich lipoproteins. Since nicotine is one of the major hazar dous components present in cigarette smoke and tobacco, one can extrap olate that the deleterious effect exerted by nicotine on rats extends to cigarette smokers and those who use other forms of tobacco.