Cholesterol ester turnover in isolated liver cells. Effects of cholesterol feeding.
Isolated hepatocytes from rats that had been kept in a steady state of [3H]cholesterol were incubated in a salt medium with or without serum. The cells released esterified cholesterol into the incubation medium as lipoproteins. This secretion, 18.1 +/- 0.5 nmol/h per g of cells, was increased when the cells were incubated in a medium containing serum (46.3 +/- 4.9 nmol/h per g of cells). This secretion was strikingly enhanced by cholesterol feeding (1% in the diet, 30 days) to 323-620 nmol/h per g of cells, and inhibited by cycloheximide, colchicine or EDTA. After removal of EDTA and addition of calcium, the cholesterol ester secretion was restored. Free cholesterol of previously labelled high-density lipoproteins (HDL) was exchanged (t1/2 = 30 min) with that of liver cells and esterified. The esterification rate (25.8 +/- 2.5 nmol/h per g of cells) was increased by cholesterol feeding (1% in the diet, 8 days) to 63.2 +/- 2.8 nmol/h per g of cells. No cholesteryl ester hydrolysis was detected with the isolated liver cells. Consequently, it is suggested that the turnover of hepatic cholesteryl ester was caused mainly by secretion in lipoproteins.
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002478:Cells, Cultured; D002784:Cholesterol / Q000378:metabolism*; D002788:Cholesterol Esters / Q000378:metabolism*; D004492:Edetic Acid / Q000494:pharmacology; D006868:Hydrolysis; D008075:Lipoproteins, HDL / Q000378:metabolism; D008099:Liver / Q000378:metabolism*; D008297:Male; D051381:Rats
D002788:Cholesterol Esters; D008075:Lipoproteins, HDL; D002784:Cholesterol; D004492:Edetic Acid; D002118:Calcium