Cytochrome P-450 arachidonic acid epoxygenase. Regulatory control of the renal epoxygenase by dietary salt loading

Jorge H. Capdevila, Shouzou Wei, Jin Yan, Armando Karara, Harry R. Jacobson, J R Falck, F. Peter Guengerich, Raymond N. DuBois

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Abstract

The rat kidney microsomal epoxygenase catalyzed the asymmetric epoxidation of arachidonic acid to generate as major products: 8(R),9(S)-, 11(R),12(S)- and 14(S),15(R)-epoxyeicosatrienoic acids with optical purities of 97, 88, and 70%, respectively. Inhibition studies utilizing a panel of polyclonal antibodies to several rat liver cytochrome P-450 isoforms, indicated that the renal epoxygenase(s) belongs to the cytochrome P-450 2C gene family. Dietary salt, administered either as a 2-2.5% (w/v) solution in the drinking water or as a modified solid diet containing 8% NaCl (w/w), resulted in marked and selective increases in the renal microsomal epoxygenase activity (416 and 260% of controls, for the liquid and solid forms of NaCl, respectively) with no significant changes in the microsomal ω/ω-1 oxygenase or in the hepatic arachidonic acid monooxygenase reaction. Immunoblotting studies demonstrated that dietary salt induced marked increases in the concentration of a cytochrome P-450 isoform(s) recognized by polyclonal antibodies raised against human liver cytochrome P-450 2C10 or rat liver cytochrome P-450 2C11. Comparisons of the stereochemical selectivity of the induced and non-induced microsomal epoxygenase(s) with that of purified rat liver cytochrome P-450 2C11 suggest that the salt-induced protein(s) is catalytically and structurally different from liver cytochrome P-450 2C11. The in vivo significance of dietary salt in regulating the activities of the kidney endogenous arachidonic acid epoxygenase was established by the demonstration of a salt-induced 10-20-fold increase in the urinary output of epoxygenase metabolites. These results, in conjunction with published evidence demonstrating the potent biological activities of its metabolites, suggest a role for the epoxygenase in the renal response to dietary salt.

Original languageEnglish (US)
Pages (from-to)21720-21726
Number of pages7
JournalJournal of Biological Chemistry
Volume267
Issue number30
StatePublished - Jan 1 1992

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ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

Capdevila, J. H., Wei, S., Yan, J., Karara, A., Jacobson, H. R., Falck, J. R., Guengerich, F. P., & DuBois, R. N. (1992). Cytochrome P-450 arachidonic acid epoxygenase. Regulatory control of the renal epoxygenase by dietary salt loading. Journal of Biological Chemistry, 267(30), 21720-21726.