Accumulation of Lipids in the Leukocytes of Rats Fed Atherogenic Diets.

Wistar rats were fed various atherogenic diets containing 5% cholesterol, 0.3y0 thiouracil, 2y0 bile salt, and 40% fat (butter, corn oil, peanut oil, or medium-chain triglycerides (MCT)). Blood specimens were obtained weekly for counting lipid-laden leukocytes (lipophages) and serum cholesterol levels were determined. The lipophages in circulating blood were defined as leukocytes, usually monocytes and lymphocytes, containing more than one vacuole stainable with oil red 0 in the cytoplasm. Rats fed the butter diet showed significantly higher numbers of lipophages and higher levels of serum total cholesterol than any other group, and grossly recognizable atherosclerosis of the thoracic and abdominal aorta was present only in these rats. The number of lipophages in circulating blood did not necessarily correspond to levels of blood cholesterol ; the group of rats fed MCT had a relatively high level of blood cholesterol and low count in lipophages. Lipidosis on the aortic valve of the heart was noted on rats of all groups after two months on the diet. Postprandial hyperlipemia did not affect the frequency of circulating lipophages in these hypercholesterolemic rats compared with the rats fasted for 16 hr in the same group.