Metabolism of acrylonitrile to 2-cyanoethylene oxide in F-344 rat liver microsomes, lung microsomes, and lung cells.

The metabolism of acrylonitrile to the epoxide, 2-cyanoethylene oxide (ANO) was examined in rat liver microsomes, lung microsomes, and isolated enriched lung cell preparations. GC/high resolution MS was used to quantitate ANO in microsomal and cellular extracts by monitoring the fragment ion C2H3N (m/z 41.0265). The limit of detection was 0.05 pmol of ANO/0.5 microliter of standard solution, microsomal extract, or cellular extract injected onto the column, and the linear range of analysis was 0.05 to 12.5 pmol of ANO. Kinetic parameters of Vmax, V/K, and Km were calculated for microsomal ANO formation. Liver microsomes were quantitatively more active than lung microsomes on a mg of protein basis. The Vmax (pmol of ANO formed/min/mg of protein) was 666.61 for liver and 45.07 for lung microsomes. The V/K (pmol of ANO/min/mg of protein/microM) was 12.83 for liver and 0.02 for lung microsomes. The apparent Km was 51.93 microM and 1853.83 microM for liver and lung microsomes, respectively. When calculated as nmol of ANO formed/min/nmol of microsomal P-450, the Vmax for lung was equivalent to the Vmax for liver. ANO formation in the rat lung was cell specific. The rates of metabolism in the Clara cell-enriched fraction, the alveolar type II cell-enriched fraction, and the cell suspension were 2.55, 0.38, and 0.67 pmol of ANO formed/min/mg of protein, respectively. No metabolism was observed in the endothelial (small) cell-enriched fraction or in the alveolar macrophages. The results suggest that the lung contributes to the metabolism and disposition of inhaled acrylonitrile.

[1]  A. E. Roberts,et al.  Effect of glutathione depletion on the irreversible association of acrylonitrile with tissue macromolecules after oral administration to rats. , 1988, Toxicology and applied pharmacology.

[2]  S. Belinsky,et al.  Factors regulating activation and DNA alkylation by 4-(N-methyl-N-nitrosamino)-1-(3-pyridyl)-1-butanone and nitrosodimethylamine in rat lung and isolated lung cells, and the relationship to carcinogenicity. , 1988, Cancer research.

[3]  C. Plopper,et al.  The distribution of cytochrome P-450 monooxygenase in cells of the rabbit lung: an ultrastructural immunocytochemical characterization. , 1988, Molecular pharmacology.

[4]  J. Ward,et al.  Immunohistochemical determination of inducibility phenotype with a monoclonal antibody to a methylcholanthrene-inducible isozyme of cytochrome P-450. , 1987, Cancer research.

[5]  S. Belinsky,et al.  Cell selective alkylation of DNA in rat lung following low dose exposure to the tobacco specific carcinogen 4-(N-methyl-N-nitrosamino)-1-(3-pyridyl)-1-butanone. , 1987, Cancer research.

[6]  M. O'berg,et al.  Cancer incidence and mortality among workers exposed to acrylonitrile. , 1987, American journal of industrial medicine.

[7]  M. O'berg,et al.  Epidemiologic study of workers exposed to acrylonitrile: an update. , 1985, Journal of occupational medicine. : official publication of the Industrial Medical Association.

[8]  D. Northrop.  Fitting enzyme-kinetic data to V/K. , 1983, Analytical biochemistry.

[9]  F. Guengerich,et al.  Metabolism of acrylonitrile by isolated rat hepatocytes. , 1983, Cancer research.

[10]  K. Pyykkö.  Time-course of effects of toluene on microsomal enzymes in rat liver, kidney and lung during and after inhalation exposure. , 1983, Chemico-biological interactions.

[11]  K. G. Jones,et al.  Benzo(a)pyrene hydroxylase activity in enriched populations of Clara cells and alveolar type II cells from control and beta-naphthoflavone-pretreated rats. , 1982, Cancer research.

[12]  R. Monson,et al.  Mortality among rubber workers: VI. Men with potential exposure to acrylonitrile. , 1982, Journal of occupational medicine. : official publication of the Industrial Medical Association.

[13]  M. Boyd,et al.  In vitro metabolic activation of the pulmonary toxin, 4-ipomeanol, in nonciliated bronchiolar epithelial (Clara) and alveolar type II cells isolated from rabbit lung. , 1982, The Journal of pharmacology and experimental therapeutics.

[14]  J. B. Werner,et al.  Mortality of United Kingdom acrylonitrile polymerisation workers. , 1981, British journal of industrial medicine.

[15]  T. Devereux,et al.  Xenobiotic metabolism by alveolar type II cells isolated from rabbit lung. , 1981, Biochemical pharmacology.

[16]  T. Devereux,et al.  Isolation of pulmonary cells and use in studies of xenobiotic metabolism. , 1981, Methods in enzymology.

[17]  F. Guengerich,et al.  In vitro metabolism of acrylonitrile to 2-cyanoethylene oxide, reaction with glutathione, and irreversible binding to proteins and nucleic acids. , 1981, Cancer research.

[18]  C. Wolf,et al.  Cytochrome p-450: localization in rabbit lung. , 1980, Science.

[19]  M. Boyd,et al.  The pulmonary clara cell as a target for toxic chemicals requiring metabolic activation; studies with carbon tetrachloride. , 1980, The Journal of pharmacology and experimental therapeutics.

[20]  M. Boyd,et al.  In vitro studies on the metabolic activation of the pulmonary toxin, 4-ipomeanol, by rat lung and liver microsomes. , 1978, The Journal of pharmacology and experimental therapeutics.

[21]  C. Maltoni,et al.  Carcinogenicity bioassays on rats of acrylonitrile administered by inhalation and by ingestion. , 1977, La Medicina del lavoro.

[22]  M. Boyd.  Evidence for the Clara cell as a site of cytochrome P450-dependent mixed-function oxidase activity in lung , 1977, Nature.

[23]  A. Boobis,et al.  Effect of washing the hepatic microsomal fraction in sucrose solutions and in sucrose solution containing EDTA upon the metabolism of foreign compounds. , 1975, Biochemical pharmacology.

[24]  R. Estabrook,et al.  The Spectrophotometric Measurement of Turbid Suspensions of Cytochromes Associated with Drug Metabolism , 1972 .