Covalent modification of hepatic microsomal lipids of rats by carbon tetrachloride
- Univ. of Texas Medical Branch, Galveston (USA)
The present study was undertaken to isolate and identify various lipids bound to 14C label during hepatic microsomal metabolism of 14CCl4 in vitro under anaerobic conditions and in vivo in rats. The two major radioactive fractions identified by thin-layer chromatography each for neutral lipids and phospholipids from in vitro and in vivo experiments corresponded to fatty acids and triglycerides and to phosphatidylcholine (PC) and phosphatidylethanolamine (PE), respectively. Approximately 89% of the radioactivity associated with phospholipids was found in PC and PE fractions. Hydrolysis of PC and PE with phospholipase A2 released about 50% of the total radioactivity as lipid moieties corresponding to fatty acids. The radioactive neutral lipids and the lipid moieties hydrolyzed from PC and PE were methylated with boron trifluoride in methanol. These methylated lipids were separated by reversed-phase high-performance liquid chromatography (HPLC), and the elution profiles of 14C label found for the lipids obtained from in vitro experiments were similar to those from in vivo. The major radioactive fractions eluted immediately after methyl oleate were identified as trichloromethyloctadecenoic and trichloromethyleicosatrienoic acid methyl esters by chemical ionization mass spectrometry. The mass spectral analysis of these fractions also indicated the formation of dichlorocarbene adduct of oleic acid. However, similar mass spectrometric detection of trichloromethylated lipids was not evident in neutral lipids and phospholipids isolated from in vivo studies. The 14C-labeled lipids eluted as a nonpolar fraction exhibited a high molecular weight containing more than three chlorines. Dimerization and cross-linking of trichloromethylated lipids based on HPLC and mass spectral analysis are also discussed in this paper.
- OSTI ID:
- 5978031
- Journal Information:
- Molecular Toxicology; (USA), Vol. 2:3; ISSN 0883-9492
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
CARBON TETRACHLORIDE
METABOLISM
LIPIDS
FRACTIONATION
CARBON 14 COMPOUNDS
COVALENCE
IN VITRO
IN VIVO
LIPASES
LIQUID COLUMN CHROMATOGRAPHY
LIVER CELLS
MASS SPECTRA
MICROSOMES
MOLECULAR WEIGHT
THIN-LAYER CHROMATOGRAPHY
TRACER TECHNIQUES
ANIMAL CELLS
CARBOXYLESTERASES
CELL CONSTITUENTS
CHLORINATED ALIPHATIC HYDROCARBONS
CHROMATOGRAPHY
ENZYMES
ESTERASES
HALOGENATED ALIPHATIC HYDROCARBONS
HYDROLASES
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
ORGANIC CHLORINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANOIDS
RIBOSOMES
SEPARATION PROCESSES
SOMATIC CELLS
SPECTRA
560300* - Chemicals Metabolism & Toxicology
550501 - Metabolism- Tracer Techniques