The role of the plasma membrane in fatty acid uptake by rat liver parenchymal cells.
1. Suspensions of isolated rat liver parenchymal cells incorporate [(14)C]palmitic acid into glycerides at about 40% of the rate obtained with liver slices. 2. At short time-intervals most of the incorporation is into phosphatidylcholine and this is recovered mainly in the plasma-membrane fraction. 3. At later times (5min to 2h) the [(14)C]palmitic acid is mainly found in triglyceride, but this is not recovered in the plasma-membrane fraction. 4. Addition of lysophosphatidylcholine increases incorporation of palmitic acid into both phosphatidylcholine and triglyceride, with maximum effect at about 0.1mm. 5. In vivo, 1min after injection of [(14)C]palmitic acid, radioactive phosphatidylcholine is concentrated in the plasma-membrane fraction, but the proportion present in this fraction declines rapidly. 6. The phosphatidylcholine of the plasma-membrane fraction has, at 1min after injection, a specific radioactivity 30-fold greater than that of the whole tissue. 7. This phosphatidylcholine reaches its maximum specific radioactivity before the tissue phosphatidic acid or diglyceride. 8. The phosphatidylcholine of the plasma-membrane fraction has a very rapid turnover. 9. It is proposed that the rapid formation of phospholipids in the plasma membrane is by acylation of their lyso-derivatives and the role of this process in fatty acid uptake is discussed.
D000215:Acylation; D000818:Animals; D002247:Carbon Isotopes; D002458:Cell Fractionation; D002462:Cell Membrane / Q000378:metabolism*; D002855:Chromatography, Thin Layer; D005989:Glycerides / Q000096:biosynthesis; D066298:In Vitro Techniques; D007700:Kinetics; D008099:Liver / Q000378:metabolism*; D008244:Lysophosphatidylcholines / Q000494:pharmacology; D010169:Palmitic Acids / Q000378:metabolism*; D010713:Phosphatidylcholines / Q000096:biosynthesis; D010743:Phospholipids / Q000096:biosynthesis; D051381:Rats; D014280:Triglycerides / Q000096:biosynthesis
D002247:Carbon Isotopes; D005989:Glycerides; D008244:Lysophosphatidylcholines; D010169:Palmitic Acids; D010713:Phosphatidylcholines; D010743:Phospholipids; D014280:Triglycerides