Characterization of cytochrome P-450-dependent arachidonic acid metabolism in rabbit intestine

C. Macica, M. Balazy, J R Falck, C. Mioskowski, M. A. Carroll

Research output: Contribution to journalArticle

32 Scopus citations

Abstract

We characterized cytochrome P-450-dependent arachidonate (P-450-AA) metabolism throughout the intestinal tract, since some metabolites derived via this pathway modify epithelial ion transport and regional blood flow. Microsomes (0.3 mg/ml) were prepared from each region of the intestines of anesthetized New Zealand White male rabbits and incubated with [14C]AA (7 μM) for 30 min at 37°C. In the presence of NADPH (1 mM), ileal microsomes exhibited the greatest P-450-AA metabolism, whereas duodenal microsomes exhibited little or no activity. For jejunal, ileal, and cecal microsomes, AA metabolism was reduced in the absence of NADPH and by boiling microsomes, was unaffected by indomethacin (10 μM) and BW-755C (50 μM), but was significantly attenuated by the P-450 enzyme inhibitors, 7-ethoxyresorufin (1 μM) and SKF-525A (100 μM). However, colonic (ascending, transverse, and descending) microsomal activity was inhibited by both P-450 and lipoxygenase inhibitors. Analysis of ileal AA metabolites by high-pressure liquid chromatography and negative ion chemical ionization gas chromatography-mass spectrometry revealed products corresponding to monohydroxyeicosatetraenoic acids (HETEs). Semiquantitative analysis showed that 20-, 19-, 18-, 17-, and 16-HETEs were present in a ratio of 6.2:3.3:0.3:0.1:0.1, respectively. Furthermore, ileal P-450-HETEs dilated the isolated perfused mesenteric bed, as did 20-HETE, the predominant ileal AA metabolite. Because 20-HETE was also shown to affect epithelial ion transport, we suggest that P-450-AA metabolites may make important contributions to intestinal function.

Original languageEnglish (US)
Pages (from-to)G735-G741
JournalAmerican Journal of Physiology - Gastrointestinal and Liver Physiology
Volume265
Issue number4 28-4
DOIs
StatePublished - 1993

Keywords

  • cytochrome P-450 hydroxylases
  • eicosanoids
  • hydroxyeicosatetraenoic acid
  • ileum
  • vasoactivity

ASJC Scopus subject areas

  • Physiology
  • Hepatology
  • Gastroenterology
  • Physiology (medical)

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