Biomedical subjects

J R Falck

Publications and source records attributed to J R Falck.

At least 181 records · Page 10Linked to original sources

PubMed1994

Effect of P-450 omega-hydroxylase metabolites of arachidonic acid on tubuloglomerular feedback.

The role of endogenous P-450 metabolites of arachidonic acid (AA) on the tubuloglomerular feedback (TGF) response was examined. Under control conditions stop-flow pressure (SFP) fell by 17.0 +/- 2.1 mmHg when the perfusion rate of the loop of Henle was increased from 0 to 50 nl/min. Addition of AA (50 microM) to the perfusate lowered basal SFP by 11.4 +/- 1.1 mmHg and potentiated the TGF response. This effect was blocked by addition of a P-450 inhibitor, 17-octadecynoic acid (17-ODYA) (10 microM), to the perfusate. Perfusion of the loop of Henle with 17-ODYA elevated basal SFP by 3.7 +/- 0.3 mmHg and reduced the TGF response by 80%. After blockade of endogenous P-450 activity with 17-ODYA, addition of 20-hydroxyeicosatetraenoic acid (20-HETE, 10 microM) to the perfusate produced a flow rate-dependent fall in SFP. The effect of 20-HETE was not altered by pretreating the animal with meclofenamate (2 mg/kg iv) or by perfusing the nephron segment with furosemide (50 microM). These results indicate that endogenous P-450 metabolites of AA, particularly 20-HETE, may play a role in TGF and the regulation of renal vascular tone.

Animals↗

PubMed1994

Experimental and/or genetically controlled alterations of the renal microsomal cytochrome P450 epoxygenase induce hypertension in rats fed a high salt diet.

Excess dietary salt induces a cytochrome P450 arachidonic acid epoxygenase isoform in rat kidneys (Capdevila, J. H., S. Wei, J. Yang, A. Karara, H. R. Jacobson, J. R. Falck, F. P. Guengerich, and R. N. Dubois. 1992. J. Biol. Chem. 267:21720-21726). Treatment of rats on a high salt diet with the epoxygenase inhibitor, clotrimazole, produces significant increases in mean arterial blood pressure (122 +/- 2 and 145 +/- 4 mmHg for salt and salt- and clotrimazole-treated rats, respectively). The salt- and clotrimazole-dependent hypertension is accompanied by reductions in the urinary excretion of epoxygenase metabolites and by a selective inhibition of the renal microsomal epoxygenase reaction. The prohypertensive effects of clotrimazole are readily reversed when either the salt or clotrimazole treatment is discontinued. The indication that a salt-inducible renal epoxygenase protects against hypertension, are supported by studies with the Dahl rat model of genetic salt-sensitive hypertension. Dahl resistant animals responded to excess dietary salt by inducing the activity of their kidney microsomal epoxygenase(s) (0.102 +/- 0.01 and 0.240 +/- 0.04 nmol of products formed/min per mg of microsomal protein for control and salt-treated rats, respectively). Despite severe hypertension during excess dietary salt intake (200 +/- 20 mmHg), Dahl salt-sensitive rats demonstrated no increase in renal epoxygenase activity. These studies indicate that acquired or inherited abnormalities in renal epoxygenase activities and/or regulation can be related to salt-sensitive hypertension in rodents. Studies on the human renal epoxygenase and its relationship to salt hypertension may prove useful.

Animals↗

PubMed1994

Stereochemical analysis and biological activity of 3-hydroxy-leukotriene B4: a metabolite from ethanol-treated rat hepatocytes.

Leukotriene B4 (LTB4), a biologically active metabolite derived from arachidonic acid by the 5-lipoxygenase cascade, is inactivated by cytochrome P-450-dependent omega-hydroxylation followed by second oxidation into a omega-carboxyl group. In many tissues, this second step is mediated by alcohol dehydrogenase. Isolated rat hepatocytes metabolized LTB4 in the presence of ethanol and ethoxyresorufin into substantial quantities of 3-hydroxy-LTB4 as determined by mass spectrometry. The absolute configuration of this metabolite was found to be greater than 98% 3(S)-hydroxy-LTB4 by comparison to synthetic standards. Investigation of the pharmacologic properties of the 3(S)- and 3(R)-hydroxy-LTB4 revealed that both caused a significant increase in intracellular free calcium in human neutrophils at 1 microM. Both enantiomers also induced thromboxane A2 release from the isolated guinea pig lung in a dose-dependent manner. This activity was fully blocked by a specific LTB4 receptor antagonist, LY223982, with an IC50 of 0.21 microM for LTB4. These results suggested that activation of the LTB4 receptor does not involve significant recognition of the carbon atoms close to the carboxyl moiety of LTB4. The failure of the hepatocyte to metabolically inactivate LTB4 in the presence of ethanol may be of importance to humans, particularly because the bioactive metabolite 3(S)-hydroxy-LTB4 was further metabolized by human neutrophils significantly more slowly than LTB4.

Animals↗

PubMed1993

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

A cDNA containing an open reading frame coding for the rat kidney cytochrome P-450 arachidonic acid epoxygenase was isolated from a male rat kidney cDNA library. Sequence analysis showed that with the exception of 11 nucleotides, this cDNA is identical with the published sequence for rat liver cytochrome 2C23 and encodes a polypeptide of 494 amino acids. Nucleic acid blot hybridization indicated that the levels of expression of the corresponding mRNA are high in rat kidney and liver and are undetectable in brain and heart. The cDNA coding region was cloned into a pCMV2 vector and expressed in COS-1 cells. The recombinant microsomal protein catalyzed the NADPH-dependent metabolism of arachidonic acid to a mixture of 5,6-, 8,9-, 11,12-, and 14,15-epoxyeicosatrienoic acids as the only oxygenation products. The enantiofacial selectivity of the recombinant protein was nearly identical with that reported for the kidney microsomal enzyme and generated 8(R),9(S)-, 11(R),12(S)-, and 14(S),15(R) with optical purities of 95, 85, and 75%, respectively. On the basis of mRNA abundance and the close similarities between the regio- and stereochemical selectivity of the recombinant and kidney microsomal proteins, we concluded that cytochrome P-450 2C23 is the predominant enzyme isoform responsible for arachidonic acid epoxidation in the rat kidney.

Amino Acid Sequence↗

PubMed1993

Renal vasodilator activity of 5,6-epoxyeicosatrienoic acid depends upon conversion by cyclooxygenase and release of prostaglandins.

The 5,6-epoxyeicosatrienoic acid (5,6-EET), a renal vasodilator metabolite of arachidonic acid via cytochrome P450 (P450) requires cyclooxygenase for expression of its vasoactivity as the responses are inhibited by indomethacin and other aspirin-like drugs. We now report on the metabolism of 5,6-EET by rabbit kidneys in order to characterize those metabolites that may account for its vasoactivity. The 5,6-EET was injected close-arterially into the rabbit isolated Krebs-Henseleit perfused kidney, preconstricted with phenylephrine, and the effluent collected throughout the response period. Basal collections, following injection of 100 microliters of vehicle, were made at 20-min intervals before each 5,6-EET injection. Prior to acidic extraction, deuterated 6-keto-prostaglandin (PG) F1 alpha and PGE2 were added as internal standards. The extracts were separated by TLC and prostaglandins were derivatized for gas chromatography-mass spectrometry analysis using a negative ion chemical ionization mode. Injection of 0.5, 1, 5, 10, and 20 micrograms of 5,6-EET (n = 4) resulted in dose-related decreases in perfusion pressure of 6 +/- 2, 12 +/- 4, 21 +/- 4, 26 +/- 4, and 27 +/- 7 mm Hg, respectively. Basal perfusates contained 6-keto-PGF1 alpha and PGE2, levels of which were increased by 2-fold or more by 5,6-EET. Perfusates, collected during 5,6-EET administration, also contained 5-hydroxy-PGI1 and 5,6-epoxy-PGE1, cyclooxygenase metabolites of 5,6-EET. This is the first report of the recovery and identification of these 5,6-EET metabolites from an intact organ. Since the responses to 5,6-EET are endothelial-dependent, we also studied the profile of eicosanoids formed following incubation of 5,6-EET with cultured bovine pulmonary endothelial cells. Endothelial cells metabolized 5,6-EET to products with a similar radioactive profile on reverse-phase high pressure liquid chromatography compared to kidney perfusates. We compared the vasodilator activity of 5,6-epoxy-PGE1 and 5-hydroxy-PGI1, chemically synthesized by us from PGE2 and PGF2 alpha, respectively, with PGE2 and PGI2 in the rabbit kidney. The 5,6-epoxy-PGE1 was equipotent to PGE2 as a vasodilator. The ED50 values for 5,6-EET, 5,6-epoxy-PGE1, and PGE2 were 4.69, 0.43, and 0.42 nmol, respectively. Although PGI2 was a potent vasodilator (ED50, 0.24 nmol), 5-hydroxy-PGI1 was devoid of activity. Thus, the cyclooxygenase-dependent vasoactivity of 5,6-EET in the rabbit kidney has two components: release of vasodilator prostaglandins, PGE2 and PGI2, and metabolism of 5,6-EET to a prostaglandin analog, 5,6-epoxy-PGE1.

8,11,14-Eicosatrienoic Acid↗

PubMed1993

Formation of 19(S)-, 19(R)-, and 18(R)-hydroxyeicosatetraenoic acids by alcohol-inducible cytochrome P450 2E1.

When reconstituted with cytochrome b5 and NADPH cytochrome P450 oxidoreductase, cytochrome P450 2E1 metabolized lauric, stearic, oleic, linoleic, linolenic, and arachidonic acid to multiple metabolites. Two major metabolites, accounting for 78% of the total metabolism, were produced with arachidonic acid. The Vmax for total metabolite formation from arachidonic acid was 5 nmol/min/nmol P450 with an apparent Km of 62 microM. Gas chromatography-mass spectrometry analysis identified the two major metabolites as monohydroxylated eicosatetraenoic acids (HETEs). The major HETE was 19-hydroxyeicosatetraenoic acid (19-HETE) and comprised 46% of the total metabolite produced. The second metabolite was the omega-2 hydroxylated metabolite (18-HETE) and comprised 32% of the total product formed. Chiral analysis demonstrated that 19-HETE was 70% 19(S)-HETE and 30% 19(R)-HETE. In contrast, 18-HETE was essentially 100% R isomer. Approximately 18% of the total metabolite produced from arachidonic acid coeluted with epoxyeicosatrienoic acid (EET) standards. The EET metabolites were 56.4% 14,15-EET and 43.6% as a mixture of 11,12-EET and 8,9-EET. 5,6-EET was not detected. Anti-P450 2E1 IgG inhibited arachidonic acid metabolism by renal and hepatic microsomes prepared from acetone-treated rabbits. With renal cortex microsomes, the formation of 18-HETE and 19-HETE was inhibited 67 and 25%, respectively, by the antibody. Liver microsomal formation of 18-HETE was inhibited by 87% and 19-HETE by 70%. Thus, under conditions where cytochrome P450 2E1 is induced, the enzyme could contribute significantly to the formation of the omega-1 and omega-2 hydroxylated metabolites of arachidonic acid.

Acetone↗

PubMed1993

20-hydroxyeicosatetraenoic acid is an endothelium-dependent vasoconstrictor in rabbit arteries.

Recently we have demonstrated that 20-hydroxy-5,8,11,14-eicosatetraenoic acid (20-HETE) constricts rat aortic rings and that this effect is cyclooxygenase- and endothelium-dependent. Incubation of 20-HETE with ram seminal vesicles, a rich source of cyclooxygenase, led to the identification of vasoconstrictor metabolites, the 20-hydroxy-endoperoxides. In the present study, we demonstrated differences in the potency of 20-HETE to constrict several arteries. In all blood vessels tested, the 20-HETE contractile effect was cyclooxygenase- and endothelium-dependent. Differences in contractile potency of 20-HETE varied according to the blood vessels; potency being higher in more muscular arteries than elastic ones. Furthermore, 20-HETE was more potent in eliciting vasoconstriction than its precursor, arachidonic acid. We also provide evidence for the generation of 20-hydroxy-endoperoxides from 20-HETE by the endothelial cyclooxygenase. 20-HETE is a major arachidonate metabolite formed by the cytochrome P450 monooxygenases in rat, human and rabbit kidneys. In addition, blood cells such as leukocytes have the ability to produce 20-HETE, suggesting its presence in the circulation. Furthermore, 20-HETE has been shown to inhibit platelet aggregation. Thus, the ability of 20-HETE to modulate vascular tone and platelet function implicates a role for this compound in the regulation of hemostasis.

Animals↗

PubMed1993

Regio- and enantiofacial selectivity of epoxyeicosatrienoic acid hydration by cytosolic epoxide hydrolase.

The hydration of cis-epoxyeicosatrienoic acids to the corresponding vic-dihydroxyeicosatrienoic acids by cytosolic epoxide hydrolase demonstrates moderate regioselectivity with rates of hydration highest for the 14,15-epoxide and lower for the 11,12- and 8,9-epoxide (4.5, 1.6, and 1.5 mumol of product/mg of protein/min, respectively). Incubations of the 8,9- and 14,15-epoxides with cytosolic epoxide hydrolase show stereoselective formation of diols (7:3 and 4:1 ratio of antipodes, respectively) and concomitant chiral enrichment of the remaining unmetabolized substrate. In contrast, hydration of the 11,12-epoxide is nonenantioselective. The Km value of the enzyme for the 14(R),15(S)-epoxide is 3 microM. Incubations of the enantiomerically pure 8,9- and 14,15-epoxides with lung or liver cytosol, followed by chiral analysis of the resulting diols demonstrate selective cleavage of the oxirane ring at C9 and C15, respectively. On the other hand, cleavage of the 11,12- oxirane ring was less selective. The stereochemical preference of the cytosolic epoxide hydrolase, together with the known chiral composition of the endogenous arachidonate epoxide pools, suggests a functional role for this enzyme in the metabolism of these important compounds.

8,11,14-Eicosatrienoic Acid↗

PubMed1993

Cytochrome P450-dependent arachidonate metabolites affect renal transport in the rabbit.

Arachidonic acid (AA) inhibited 86Rb uptake in a dose-dependent manner in rabbit medullary tubules representing the thick ascending limb of the loop of Henle (mTALH). We have shown that CoCl2 treatment of rabbits reduced renal AA metabolism by cytochrome P450-dependent enzymes (P450). After CoCl2 treatment, AA was without effect on 86Rb uptake in mTALH cells. However, the two principal P450-AA metabolites produced by the mTALH, 20-HETE and 20-COOH-AA, inhibited 86Rb uptake in a dose-dependent manner in mTALH cells whether obtained from control or CoCl2-treated rabbits. These data support our hypothesis that CoCl2 treatment impairs ion transport function of mTALH cells by blocking cytochrome P450-AA metabolism, a blockade circumvented by the relevant P450-AA metabolites.

Animals↗

PubMed1993

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

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 microM) for 30 min at 37 degrees 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 microM) and BW-755C (50 microM), but was significantly attenuated by the P-450 enzyme inhibitors, 7-ethoxyresorufin (1 microM) and SKF-525A (100 microM). 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.

Animals↗

PubMed1993

Elevated renovascular tone in young spontaneously hypertensive rats. Role of cytochrome P-450.

The present study examined the role of cytochrome P-450 metabolites of arachidonic acid in elevating renal vascular resistance in young spontaneously hypertensive rats (SHR). Differences in vascular tone were assessed in the preglomerular vasculature of 3- to 4-week-old prehypertensive SHR (n = 11) and normotensive Wistar-Kyoto (WKY, n = 10) and Wistar-Lewis (n = 10) rats. Pressure-diameter relations to changes in renal perfusion pressure were compared using the juxtamedullary nephron microvascular preparation perfused in vitro with a physiological salt solution. At a pressure of 60 mm Hg, the basal diameters of the interlobular arteries and proximal and distal afferent arterioles of the SHR averaged 43 +/- 2, 17 +/- 0.3, and 11 +/- 0.4 microns, respectively. The diameters of the interlobular arteries and afferent arterioles were 9% to 14% smaller than those of corresponding vessels in WKY and Wistar-Lewis rats. Addition of P-450 inhibitors, ketoconazole (100 mumol/L) or 7-ethoxyresorufin (1 mumol/L), to the perfusate dilated the afferent arteriole of SHR by 7% to 12%, whereas it increased the diameter by only 0% to 6% in control rats and significantly reduced the differences in the pressure-diameter relation in the preglomerular vasculature of SHR and control rats. Inhibitors of P-450 eliminated the contractile response of afferent arterioles to increases in renal perfusion pressure in all three groups. Removal of calcium from the perfusate eliminated differences in the diameters of the preglomerular vasculature in SHR and normotensive rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗

PubMed1993

20-Hydroxyeicosatetraenoic acid is an endogenous vasoconstrictor of canine renal arcuate arteries.

Recent studies have indicated that renal arteries can produce 20-hydroxyeicosatetraenoic acid (20-HETE) and suggest the potential involvement of a P450 metabolite of arachidonic acid in the myogenic activation of canine renal arteries. In the present study, the effects of 20-HETE on isolated canine renal arcuate arteries were studied. Administration of 20-HETE to the bath or the lumen at concentrations of 0.01-1 microM produced a graded reduction in the diameter of these vessels. In contrast, 19(R)-HETE was a vasodilator, whereas 19(S)-HETE was relatively inactive. The vasoconstrictor response to 20-HETE was not altered by the cyclooxygenase inhibitor indomethacin, endoperoxide/thromboxane receptor antagonist SQ29548, or combined blockade of the cyclooxygenase, lipoxygenase, and P450 pathways using indomethacin, baicalein, and 7-ethoxyresorufin. The response to 20-HETE was associated with depolarization and a sustained increase in the intracellular calcium concentration in renal vascular smooth muscle cells. Patch-clamp studies indicated that 20-HETE significantly reduced mean open time, the open-state probability, and the frequency of opening of a 117-pS K+ channel recorded from renal vascular smooth muscle cells in the cell-attached mode. Microsomes prepared from the renal cortex of dogs produced 20-HETE and 20-carboxyarachidonic acid when incubated with [14C]arachidonic acid. These results indicate that 20-HETE is an endogenous constrictor of canine renal arcuate arteries. The vasoconstrictor response to 20-HETE resembles the myogenic activation of these vessels after elevations in transmural pressure and suggests a potential role for this substance in the regulation of renal vascular tone.

Animals↗

PubMed1993

Metabolism of arachidonic acid to epoxyeicosatrienoic acids by human granulosa cells may mediate steroidogenesis.

Epoxyeicosatrienoic acids (EETs), cytochrome P-450 metabolites of arachidonic acid, have attracted attention because of their effects on stimulus-response coupling in endocrine, renal, and vascular cells. To investigate a possible role for EETs in ovarian physiology, we conducted a series of experiments using human luteinized granulosa cells. Granulosa cell microsomes produce EETs, which are identified by their comigration with known standards using reverse phase high pressure liquid chromatography. EET synthesis by granulosa cells is NADPH dependent and inhibited by ketoconazole, suggesting an enzymatic mechanism of production. Intact granulosa cells synthesize EETs from exogenous arachidonic acid, and EET production is increased by hCG stimulation of the cells. To investigate whether EETs have a role in ovarian steroidogenesis, they were added to cultures of granulosa cells. Varying concentrations of 14,15-EET differentially affected estradiol secretion; 0.001-0.05 microM stimulated estradiol production, whereas 14,15-EET concentrations of 10-50 microM inhibited estradiol production. hCG-stimulated estradiol secretion was also inhibited by 10-50 microM 14,15-EET. In contrast, progesterone secretion was not affected by any concentration of 14,15-EET tested. The cellular concentration of cAMP was not affected by the addition of EETs. These findings suggest that hCG stimulates granulosa cell production of EETs via an NADPH-supported, cytochrome P-450-dependent enzymatic mechanism. EETs may have an important autocrine or paracrine role in regulating ovarian granulosa cell estrogen synthesis.

8,11,14-Eicosatrienoic Acid↗

PubMed1992

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

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 omega/omega-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.

8,11,14-Eicosatrienoic Acid↗

PubMed1992

20-Hydroxyeicosatetraenoic acid is excreted as a glucuronide conjugate in human urine.

20-hydroxyeicosatetraenoic acid, a major renal P-450 metabolite of arachidonic acid, has been quantified in human urine using capillary gas chromatography/electron capture negative ion chemical ionization mass spectrometry. The urinary excretion of 20-hydroxyeicosatetraenoic acid was in the low pg/ml range. However, treatment of urine with beta-glucuronidase resulted in a 13- to 28-fold increase in its concentration. This suggests 20-hydroxyeicosatetraenoic acid differs from other eicosanoids in that it is excreted primarily as a glucuronide conjugate.

Gas Chromatography-Mass Spectrometry↗

PubMed1992

Arachidonic acid epoxygenase: structural characterization and quantification of epoxyeicosatrienoates in plasma.

Gas chromatographic/mass spectroscopic and chiral analysis showed the presence of enzymatically derived 8,9-, 11,12- and 14,15-EET in rat plasma (2.8:1:3.4 molar ratio, respectively; 10.2 +/- 0.4 ng total EET/ml plasma). Greater than 90% of the plasma EETs was esterified to the phospholipids of circulating lipoproteins. The lipoprotein fraction with the highest EET concentration was LDL (8.1 +/- 0.9 ng/mg of protein) followed by HDL and VLDL (3.5 +/- 0.1 and 1.9 +/- 0.3 ng/mg of protein, respectively). In light of the biological activities of the EETs, these results suggest a potential systemic function for the cytochrome P-450 epoxygenase.

8,11,14-Eicosatrienoic Acid↗

PubMed1992

Cytochrome P450 and the arachidonate cascade.

Arachidonic acid and many products of the arachidonate cascade serve as substrates for cytochrome P450-mediated metabolism via allylic oxidation, omega hydroxylation, and epoxygenation as well as peroxide rearrangement. Defining the physiological importance of these metabolites is an area of intense research interest. Cytochrome P450-catalyzed reactions play prominent roles in multiplying the structural and functional diversity of the arachidonate metabolic cascade.

Animals↗

PubMed1992

Metabolism of 12(R)-hydroxyeicosatetraenoic acid by rat liver microsomes.

The in vitro metabolism of 12(R)-hydroxyeicosatetraenoic acid was studied using freshly isolated rat liver microsomes. Ten metabolites were isolated and identified by a combination of ultraviolet spectroscopy and gas chromatography/mass spectrometry. The two major metabolites were dihydroxyeicosatetraenoic acids generated by omega/omega-1 hydroxylation. Oxidation at C-5 resulted in the formation of four leukotriene-like compounds, two of which differed from leukotriene B4 in double-bond geometry alone. The other two differed from leukotriene B4 in olefin geometry and C-5 configuration. Epoxidation at the 14,15-olefin resulted in the formation of two diastereomeric epoxy alcohols, while C-16 hydroxylation gave two diastereomeric dihydroxyeicosatetraenoic acids.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗