The Fatty Acids of Total Lipids and Cholesterol Esters from Normal Plasma and Atheromatous Plaques1

In order to elucidate the mechanism of atheroma formation in arteriosclerosis, the lipid fractions of plasma and atheromatous plaques have been ex- tensively studied in the past 45 years. It was first noted that there is a high content of cholesterol, phospholipid and total extractable lipids in ather- omatous aortas (1-4). Then came a period when studies dealt primarily with the changing ratios between total, free and esterified cholesterol and phospholipids in normal plasma and atheromatous plaques (5-8). Considerable work has been done in the past decade to correlate the changes in blood cholesterol, phospholipids and lipoproteins with the incidence of arteriosclerosis (9-15). Com- paratively little work has been done, however, on the isolation and identification of fatty acids associated with different lipid fractions of plasma and atheromatous plaques, the lack of adequate meth- ods for fatty acid analysis being the most likely explanation. Schoenheimer (3) isolated the cho- lesterol esters of stearic, oleic and palmitic acids from the adventitia-free atheromatous aorta. In addition to these acids, McArthur (16) isolated linoleic and arachidonic acids from aortic plaques. As far as the fatty acids of the blood are con- cerned, the main sources of information are alkali isomerization studies (17-19) and studies done on the blood of large mammals (20). Recently, more information based on paper (21), column (22) and gas-liquid (23) chromatographic analy- sis of fatty acids of human blood has been reported. However, no comparative studies are available on material from human beings, using the same analytical methods to determine the fatty acids in blood and atheromatous plaques. There have been isolated reports suggesting that the blood of popu-