Lipid composition of fat particles from normal man and patients with idiopathic hypertriglyceridemia.

Lipemic plasma from normal and hyperlipemic patients has been fractionated on columns of 3% (w/v) aqueous polyvinylpyrrolidone (PVP) and the lipid composition of the separated fat particles (S(f) > 400) measured. Plasma from patients with carbohydrate-induced lipemia on fat-free diets contained particles with a greater percentage of cholesterol and phospholipid than either normal primary particles (which float to the top of 3% PVP columns) or secondary particles (which remain concentrated just above the plasma layer at the bottom of the 3% PVP column). These "hyperlipemia" particles remained in the lower half of 3% PVP columns, which allowed easy separation from primary (top) particles. In the same hypertriglyceridemic patients primary (top) particles with the usual lipid composition were isolated from plasma 8 hr after ingestion of 200 g of corn oil, but 24 hr after the meal, primary (top) particles isolated in the same way contained a higher percentage of cholesterol than normal primary particles. High-cholesterol primary (top) particles were isolated from the patients mentioned and also from patients with fat-induced lipemia after an overnight fast on a regular fat-containing diet. It is concluded that the lipid composition of primary particles is variable and reflects the length of time these particles have been in the general circulation.