Lipid composition and erucic acid in rat liver cells in culture.

Abstract

AbstractErucic acid (Δ13‐docosenoic acid) was added to fetal calf serum, then fed to rat liver epithelial cells in culture, and uptake measured at intervals over 24 hr. During the first 6 hr. of incubation, uptake of the docosenoic acid was 21 nmoles/hr/mg protein in 7‐day cells, and 15 mmoles/hr/mg protein in 14‐day cells. Of14C‐labeled erucic acid taken up by the cells in 24 hr, radioactivity measurements showed 60% of the total lipid14C activity derived from [1‐14C] 22∶1 in neutral lipid (NL) and 40% in phospholipid (PL); whereas 55% of lipid14C activity was in NL and 45% in PL when the substrate was [14‐14C] 22∶1. Within the NL fraction, 75% of14C activity derived from [1‐14C] 22∶1 was in triglyceride (TG) and 11% in cholesterol (CHL), while 79% was in TG and 6.5% in CHL when the substrate was [14‐14C] 22∶1. Triglycerides and cholesteryl esters accumulated in the cells during incubation with erucic acid. Among phospholipids separated by thin layer chromatography, 75% of14C activity was in lecithin (PC), 10% in phosphatidylethanolamine (PE), 5% in sphingomyelin (SPH), and 1% or less in cardiolipin (DPG). The highest specific activity (SA) was in PC, followed by SPH and PE. Incubation with erucic acid altered fatty acid composition of PC, PE, and SPH, although amounts of phospholipids were unaffected. Gas liquid chromatography analyses detected 18% erucic acid in PC, 2% in PE, and 4–5% in SPH.