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Lipid takes a stand against alcohol.

Lipid takes a stand against alcohol

Chronic alcohol consumption does unpleasantthings to the body. But there is an interesting twist to the story of alcohol's effects: Scientists have known for several years that frequent ingestion of ethanol also alters cells in an apparently positive way. Normally, when cell membranes come into contact with ethanol, their lipid molecules begin moving more freely, a change that may affect normal enzyme function. Chronic consumption of ethanol, however, results in some celular membranes that are unaffected by ethanol.

This resistance has been cited as a possiblemechanism of tolerance in alcoholics. But exactly why it occurs has remained a mystery. Now, a study from Philadelphia's Thomas Jefferson university School of Medicine offers the 2.5 percent solution.

Researchers isolated different phospholipids,a major kind of membrane lipid, from cell structures in the livers of rats fed ethanol for 35 days (ethanol accounted for 36 percent of total calories), and from rats fed an ethanol-free diet. By suspending varying mixtures of those phospholipids in saline solution, the researchers made liposomes -- spherical compartments surrounded by a lipid bilayer -- and later used them to assess membrane damage.

They found not only that phospholipidsfrom the ethanol-fed rats protected the liposomes from ethanol, but also that only 30 to 40 percent of the phospholipids in the membrane needed to be from those rats. After further refining the system, the researchers concluded that a single phospholipid is responsible: phosphatidylinositol (PtdIns), which in purified form can protect in concentrations as low as 2.5 percent of the total phospholipid content of membranes.

The ethanol tolerance can develop inmembranes from other organs as well, according to a report in the December PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES (Vol. 83, No. 24). Theodore F. Tarasachi, a member of the research team, told SCIENCE NEWS that they currently are studying the structure of PtdIns to explain its protective role, and that similar experiments using human blood are under way. He says unpublished work by the Philadelphia group also suggests that a different phospholipid from another celular structure works in the same way. Studying ethanol's effects at the membrane level should increase the understanding of alcoholism in general, as well as suggest new approaches to treatment. Last month, a report from the National Institute of Mental Health described a new drug that may prove useful in stopping the intoxicating effects of alcohol by affecting the movement of chloride
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Title Annotation:effect of alcohol on cell membranes
Author:Edwards, Diane D.
Publication:Science News
Date:Jan 17, 1987
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