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Metabolism of chylomicrons by the isolated rat liver

1967; Elsevier BV; Volume: 8; Issue: 2 Linguagem: Inglês

10.1016/s0022-2275(20)38920-3

1539-7262

Joseph A. Ontko, D.B. Zilversmit,

Eicosanoids and Hypertension Pharmacology

Isolated livers perfused with washed corn oil chylomicrons labeled in vivo with palmitic acid-1 -14C removed a large proportion of the chylomicrons. Slices from these livers oxidized chylomicron fatty acid esters to both carbon dioxide and acetoacetate. The liver slices also generated free fatty acids from chylomicron lipids and converted chylomicron tri- glycerides to phospholipids. Similar activities were observed in rat liver slices prepared shortly after the intravenous adminis- tration of chylomicrons to intact rats. The observed chylomicron uptake and lipid conversions were similar in livers from both fed and fasted rats. Fasting in- creased the oxidation of chylomicron fatty acid esters by livers labeled in vivo and by perfusion. In livers removed from intact rats given labeled chylomi- crons, the triglyceride-'*C to pho~pholipid-~*C ratio was high, a finding unexpected if the liver had acquired this 14C by re- moval of circulating fatty acids formed by extrahepatic lipoly- sis. These results demonstrate the ability of the liver to remove and utilize chylomicrons directly and suggest that direct re- moval accounts for a significant portion of the chylomicron fatty acids utilized by the liver of intact rats.