Incorporation of stearic acid (18:0) and palmitic acid (16:0) in phospholipid molecular species studied in isolated rat liver cells.
The incorporation of [1-14C]16:0 and [1-14C]18:0 in the molecular species of PC and PE in isolated rat liver cells was studied. More [14C]18:0 than [14C]16:0 was esterified both in PC and PE. Also the chain elongated and desaturated products (16:1, 18:0 and 18:1) were incorporated. The main molecular phospholipid species formed from [14C]18:0 were 18:0-18:2, 18:0-20:4 and 18:0-22:6. 18:0-18:0 species was not detected, independent of the substrate concentration (0.1-0.9 mM). With [14C]16:0 at low substrate concentration (0.1 mM) the dominating species are 16:0-18:2, 16:0-20:4 and 16:0-22:6. These species were detected already after 10 min. The same main species are formed both in PC and PE, but the relative amounts differ. In PC the combination with 18:2 is most abundant for both saturated fatty acid substrates. In PE 18:0-20:4 dominates when 18:0 is the substrate, and 16:0-22:6 when 16:0 is. At higher substrate concentrations (0.4-0.9 mM) 16:0 is also esterified in 16:0-16:0. This molecular species is efficiently degraded in the cells within 2-3 h, in contrast to the other species formed. The results suggest that 16:0 and 18:0 are directly incorporated in the sn-1 position in physiologically important phospholipid molecular species. With an excess of 16:0, 16:0-16:0 is also formed in substantial amounts, but this uncommon species is thereafter removed.
Woldseth
B
B
Institute of Clinical Biochemistry, University of Oslo, Rikshospitalet, Norway.
Christensen
E
E
Christophersen
B O
BO
D000818:Animals; D002250:Carbon Radioisotopes; D002478:Cells, Cultured; D008099:Liver / Q000378:metabolism*; D008297:Male; D019308:Palmitic Acid; D010169:Palmitic Acids / Q000378:metabolism*; D010713:Phosphatidylcholines / Q000096:biosynthesis; D010714:Phosphatidylethanolamines / Q000096:biosynthesis; D010716:Phosphatidylinositols / Q000096:biosynthesis; D010718:Phosphatidylserines / Q000096:biosynthesis; D010743:Phospholipids / Q000096:biosynthesis* / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013229:Stearic Acids / Q000378:metabolism*
D002250:Carbon Radioisotopes; D010169:Palmitic Acids; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D010716:Phosphatidylinositols; D010718:Phosphatidylserines; D010743:Phospholipids; D013229:Stearic Acids; D019308:Palmitic Acid; C031183:stearic acid