Relationship between a Glycoprotein Acting as Lipoprotein Lipase Inhibitor and Arteriosclerosis

Abstract

A glycoprotein which had inhibitory action in vitro and in vivo on plasma and tissue lipoprotein lipase was extracted from human sera and partially purified by Hollett's procedure. Inhibitory action of the glycoprotein extracted from sera of aged persons as well as patients with arteriosclerosis showed to be stronger than that from sera of young adults. On the other hand, a crude glycoprotein extracted from various tissues of dog by method of Radhakrishnamurthy et al. was found to act as a potent inhibitor of dextran-sulfate induced human plasma lipoprotein lipase, Particularly the crude glycoprotein obtained from the liver showed the strongest inhibitory effect compared to the other tissues of the dog. The liver possessed the largest quantity of the glycoprotein per weight. Further purification of the crude glycoprotein extracted from human sera was made by isoelectric focusing. It was confirmed by electrophoretic and immuno-electrophoretic analyses that a certain alpha-2 acid glycoprotein had an inhibitory activity on lipoprotein lipase. To the male rats (S.D strain), 10mg. of the crude glycoprotein extracted from sera was administered daily for 10 weeks intramuscularly. Activity of lipoprotein lipase in the various tissues, especially in aorta, was found to be lower than that of control rats. Histological examination also showed deposition of characteristic lipid droplets in aorta and arteries near pancreas, and intimal thickening of small arteries of the heart and spleen.