EFFECT OF INCREASED UPTAKE OF PLASMA FATTY-ACIDS BY THE LIVER ON LIPID-METABOLISM IN THE HEPATOCELLULAR NUCLEI

The nucleus contains different lipids. The aim of the present study wa s to examine whether increased uptake of free fatty acids by the liver affects lipid metabolism in the hepatocellular nuclei, The experiment s were carried out on three groups of Wistar rats: I - male, control; II - male, heparin-treated, and III - female, [C-14]-palmitic acid sus pended in rat donor serum was administered intravenously 5 and 30 min before tissue samples were taken. Lipids were extracted from isolated liver nuclei and separated into different fractions (phospholipids - P H, monoacylglycerols - MG, diacylglycerols - DG, cholesterol - CH, fre e fatty acids - FFA, triacylglycerols - TG and cholesterol esters - CH E). It was found that 5 min after administration of the label all isol ated nuclear lipid fractions were radioactive. Most of the radioactivi ty was located in the fraction of PH, TG and FFA. Elevation in the pla sma FFA concentration (heparin-treated group) resulted in increased in corporation of [C-14]-palmitic acid into the nuclear lipids and change s in its distribution. In the female rats the radioactivity of nuclear lipids was higher than in the male-controls. There were also differen ces in the percentage distribution of the radioactivity in different l ipid fractions between the two groups. The concentration of PH and TG in the nuclei increased only in the heparin-treated but not in the fem ale rats. However, specific activity of the nuclear PH and TG increase d in with both groups compared to the male-control group. It is conclu ded that (a) the blood-borne FFA rapidly enter the nuclear lipid pool and (b) increased uptake of the plasma-borne FFA by the liver affects the nuclear lipid metabolism.