[Catabolism of lipoprotein-X (Lp-X) induced by infusion of 10% intralipid].

In order to clarify the metabolism of Lipoprotein X (Lp-X) induced by intravenous Intralipid 10%, in vitro experiments using purified Lp-X from the sera of the patients receiving Intralipid 10% were carried out. 1) Lp-X or high density lipoprotein (HDL) was incubated with J-774 macrophages laden with [3H] cholesterol. Marked extraction of cholesterol from macrophages by Lp-X as well as HDL was observed. 2) [3H] cholesterol labelled Lp-X or oxidized LDL (o-LDL) was incubated with J-774 macrophages. Incorporation of Lp-X into macrophages was negligible comparing to o-LDL. 3) [3H] cholesterol labelled Lp-X, low density lipoprotein (LDL), or HDL was incubated with Hep G2 cells was less than LDL, but similar to that of HDL. These results indicated that Lp-X extracted cholesterol from peripheral tissues during its formation, and it was not catabolized by the scavenger pathway, but catabolized by the LDL pathway of hepatocytes.