Molecular cloning, expression, and enzymatic characterization of the rat kidney cytochrome P-450 arachidonic acid epoxygenase

Our previous studies indicated a role for cytochrome P-450-dependent enzymes in generating the mediators of the vasodilator effect of arachidonic acid (AA) in the preconstricted indomethacin-treated perfused kidney of the rat. We report that in vivo induction of cytochrome P-450 enzymes with 3-methylcholanthrene-beta-naphthoflavone or dexamethasone enhanced the renal vasodilator effect of AA in this experimental preparation. Conversely, depletion of cytochrome P-450 enzymes with stannous chloride or cobalt chloride diminished the vasodilator response to AA. Injection of AA resulted in the release of relaxant material into the renal effluent detected by superfusion of rabbit aortic rings. Inhibition of cytochrome P-450 with 7-ethoxyresorufin reduced the release of vasorelaxant material. Metabolism of labeled AA by the kidney revealed four peaks of radioactivity that were recovered from the renal effluent. The heights of these peaks were reduced by 7-ethoxyresorufin. These results provide further evidence for cytochrome P-450-dependent metabolism of AA to one or more vasodilator products by the rat kidney.

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Cytochrome P-450 Related to P-4504 from Phenobarbital-Treated Rabbit Liver: Molecular Cloning of cDNA and Characterization of Cytochrome P-450 Obtained by Its Expression in Yeast Cells1

The Journal of Biochemistry ◽

10.1093/oxfordjournals.jbchem.a121977 ◽

1987 ◽

Vol 101 (5) ◽

pp. 1129-1139 ◽

Cited By ~ 28

Author(s):

Yoshio IMAI

Keyword(s):

Molecular Cloning ◽

Rabbit Liver ◽

Cytochrome P 450

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Arachidonic acid inhibits basolateral K channels in the cortical collecting duct via cytochrome P-450 epoxygenase-dependent metabolic pathways

AJP Renal Physiology ◽

10.1152/ajprenal.00038.2008 ◽

2008 ◽

Vol 294 (6) ◽

pp. F1441-F1447 ◽

Cited By ~ 10

Author(s):

ZhiJian Wang ◽

Yuan Wei ◽

John R. Falck ◽

Krishnam Raju Atcha ◽

Wen-Hui Wang

Keyword(s):

Arachidonic Acid ◽

Collecting Duct ◽

Rat Kidney ◽

Inhibitory Effect ◽

K Channel ◽

Dependent Manner ◽

Cortical Collecting Duct ◽

Patch Clamp Technique ◽

K Channels ◽

Cytochrome P 450

We used the patch-clamp technique to study the effect of arachidonic acid (AA) on basolateral 18-pS K channels in the principal cell of the cortical collecting duct (CCD) of the rat kidney. Application of AA inhibited the 18-pS K channels in a dose-dependent manner and 10 μM AA caused a maximal inhibition. The effect of AA on the 18-pS K channel was specific because application of 11,14,17-eicosatrienoic acid had no effect on channel activity. Also, the inhibitory effect of AA on the 18-pS K channels was abolished by blocking cytochrome P-450 (CYP) epoxygenase with N-methylsulfonyl-6-(propargyloxyphenyl)hexanamide (MS-PPOH) but was not affected by inhibiting CYP ω-hydroxylase or cyclooxygenase. The notion that the inhibitory effect of AA was mediated by CYP epoxygenase-dependent metabolites was further supported by the observation that application of 100 nM 11,12-epoxyeicosatrienoic acid (EET) mimicked the effect of AA and inhibited the basolateral 18-pS K channels. In contrast, addition of either 5,6-, 8,9-, or 14,15-EET failed to inhibit the 18-pS K channels. Moreover, application of 11,12-EET was still able to inhibit the 18-pS K channels in the presence of MS-PPOH. This suggests that 11,12-EET is a mediator for the AA-induced inhibition of the 18-pS K channels. We conclude that AA inhibits basolateral 18-pS K channels by a CYP epoxygenase-dependent pathway and that 11,12-EET is a mediator for the effect of AA on basolateral K channels in the CCD.

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