The uptake of lipids by rat liver cells.

1. Unesterified cholesterol, cholesterol esters and triglycerides of chylomicrons were taken up at the same rate by isolated hepatic parenchymal cells. 2. On incubation of hepatic cells, isolated 2min. after the injection of chylomicrons in vivo, the chylomicron triglyceride associated with the cells underwent hydrolysis. 3. In cells isolated 5min. after the injection of chylomicrons, the chylomicron triglyceride bound to the hepatic cells was accessible to added clearing factor lipase. 4. ;Ghost' hepatic cells had the same binding capacity and lipolytic activity per cell as intact cells. 5. Of all subcellular fractions studied, the ;plasma membrane' fraction showed the greatest capacity per unit weight for non-esterified fatty acid and chylomicron triglyceride binding and for triglyceride hydrolysis. 6. Once non-esterified fatty acids entered the hepatic cell, they were apparently metabolized in the same manner, whether taken up from the circulation as such or derived from chylomicron triglyceride.