The rabbit pulmonary cytochrome P450 arachidonic acid metabolic pathway: Characterization and significance

D. C. Zeldin, J. D. Plitman, J. Kobayashi, R. F. Miller, J. R. Snapper, J R Falck, J. L. Szarek, R. M. Philpot, J. H. Capdevila

Research output: Contribution to journalArticle

104 Scopus citations

Abstract

Cytochrome P450 metabolizes arachidonic acid to several unique and biologically active compounds in rabbit liver and kidney. Microsomal fractions prepared from rabbit lung homogenates metabolized arachidonic acid through cytochrome P450 pathways, yielding cis-epoxyeicosatrienoic acids (EETs) and their hydration products, vic-dihydroxyeicosatrienoic acids, mid- chain cis-trans conjugated dienols, and 19- and 20-hydroxyeicosatetraenoic acids. Inhibition studies using polyclonal antibodies prepared against purified CYP2B4 demonstrated 100% inhibition of arachidonic acid epoxide formation. Purified CYP2B4, reconstituted in the presence of NADPH-cytochrome P450 reductase and cytochrome b5, metabolized arachidonic acid, producing primarily EETs. EETs were detected in lung homogenate using gas chromatography/mass spectroscopy, providing evidence for the in vivo pulmonary cytochrome P450 epoxidation of arachidanic acid. Chiral analysis of these lung EETs demonstrated a preference for the 14(R),15(S)-, 11(S),12(R)- , and 8(S),9(R)-EET enantiomers. Both EETs and vic-dihydroxyeicosatrienoic acids were detected in bronchoalveolar lavage fluid. At micromolar concentrations, methylated 5,6-EET and 8,9-EET significantly relaxed histamine-contracted guinea pig hilar bronchi in vitro. In contrast, 20- hydroxyeicosatetraenoic acid caused contraction to near maximal tension. We conclude that CYP2B4, an abundant rabbit lung cytochrome P450 enzyme, is the primary constitutive pulmonary arachidonic acid epoxygenase and that these locally produced, biologically active eicosanoids may be involved in maintaining homeostasis within the lung.

Original languageEnglish (US)
Pages (from-to)2150-2160
Number of pages11
JournalJournal of Clinical Investigation
Volume95
Issue number5
DOIs
StatePublished - May 1995

Keywords

  • dihydroxyeicosatrienoic acid
  • eicosanoid
  • epoxyeicosatrienoic acid
  • epoxygenase
  • hydroxyeicosatetraenoic acid

ASJC Scopus subject areas

  • Medicine(all)

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    Zeldin, D. C., Plitman, J. D., Kobayashi, J., Miller, R. F., Snapper, J. R., Falck, J. R., Szarek, J. L., Philpot, R. M., & Capdevila, J. H. (1995). The rabbit pulmonary cytochrome P450 arachidonic acid metabolic pathway: Characterization and significance. Journal of Clinical Investigation, 95(5), 2150-2160. https://doi.org/10.1172/JCI117904