Increased CYP2J Expression and Epoxyeicosatrienoic Acid Formation in Spontaneously Hypertensive Rat Kidney
- Zhigang Yu1,
- Linn M. Huse1,
- Peter Adler2,
- LeRae Graham2,
- Jixiang Ma2,
- Darryl C. Zeldin2 and
- Deanna L. Kroetz1
- 1Department of Biopharmaceutical Sciences, School of Pharmacy, University of California, San Francisco, California (Z.Y., L.M.H., D.L.K.); and 2Division of Intramural Research, National Institute of Environmental Health Scienes, Research Triangle Park, North Carolina (P.A., L.G., J.M., D.C.Z.)
Abstract
Epoxyeicosatrienoic acids (EETs) are major products of cytochrome P450 (CYP)-catalyzed metabolism of arachidonic acid in the kidney. The potent effect of EETs on renal vascular tone and tubular ion and water transport implicates their role in the regulation of renal function and blood pressure. The present study was designed to test the hypothesis that CYP-catalyzed EET formation was altered in the spontaneously hypertensive rat (SHR) kidney. The formation of 14,15- and 11,12-EET was ∼2-fold higher in incubations of arachidonic acid with SHR renal cortical microsomes relative to microsomes from normotensive Wistar-Kyoto (WKY) rats. This was consistent with increased expression of a CYP2J2 immunoreactive protein in the SHR cortex and outer medulla. In contrast, there was no significant difference in the levels of the CYP2E and CYP2C epoxygenases in SHR and WKY kidneys. Protein and RNA analysis suggests that the CYP2J2 immunoreactive protein that is overexpressed in the SHR kidney is distinct from the known rat CYP2J isoforms. EET formation also was documented in vivo from measurements of urinary EET excretion. Importantly, the excretion rates of 14,15-, and 11,12-EETs were 2.5- and 1.8-fold higher, respectively, in SHR than WKY kidney. These studies provide both in vitro and in vivo evidence for increased EET formation in the SHR kidney and identify a novel CYP2J2 immunoreactive protein that is differentially expressed in the hypertensive kidney. In light of the known biological properties of the EETs, these findings may be important in elucidating the mechanisms that control renal vascular tone and tubular ion transport in the SHR.
Footnotes
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Send reprint requests to: Deanna L. Kroetz, Ph.D., Department of Biopharmaceutical Sciences, 513 Parnassus, Box 0446, San Francisco, CA 94143-0446. E-mail: deanna{at}itsa.ucsf.edu
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This study was supported, in part, by a New Investigator Grant from the American Association of Colleges of Pharmacy, a Research Starter Grant from the Pharmaceutical Research and Manufacturers Association, the University of California-San Francisco Academic Senate, National Institutes of Health Grant HL53994 (to D.L.K.), and a grant from the Institute of Environmental Health Sciences Division of Intramural Research (to D.C.Z.).
- Abbreviations:
- CYP
- cytochrome P450
- EET
- epoxyeicosatrienoic acid
- 20-HETE
- 20-hydroxyeicosatetraenoic acid
- DHET
- dihydroxyeicosatrienoic acid
- SHR
- spontaneously hypertensive rat
- WKY
- Wistar-Kyoto
- GC-MS
- gas chromatography-mass spectrometry
- bp
- base pair
- nt
- nucleotide
- RT-PCR
- reverse transcription-polymerase chain reaction
- PFB
- pentafluorobenzyl
- TMS
- trimethylsilyl
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- Received August 19, 1999.
- Accepted February 11, 2000.
- The American Society for Pharmacology and Experimental Therapeutics
