Metabolic fate of radiolabeled prostaglandin D2 in a normal human male volunteer

50 microCi of [3H]prostaglandin D2 tracer (100 Ci/mmol) was infused intravenously into a normal human male volunteer. 75% of the infused radioactivity was excreted into the urine within 5 h. This urine was added to urine obtained from two mastocytosis patients with marked overproduction of prostaglandin D2. Radiolabeled prostaglandin D2 urinary metabolites were chromatographically isolated and purified and subsequently identified by gas chromatography-mass spectrometry. 25 metabolites were identified. 23 of these compounds comprising 37% of the recovered radioactivity had prostaglandin F-ring structures, and only two metabolites comprising 2.7% of the recovered radioactivity retained the prostaglandin D-ring structure. The single most abundant metabolite identified was 9,11-dihydroxy-15-oxo-2,3,18,19-tetranorprost-5-ene-1,20-dioic acid which was isolated in a tricyclic form as a result of formation of a lower side chain hemiketal followed by lactonization of the terminal carboxyl and the hemiketal hydroxyl. Different isomeric forms of several prostaglandin F-ring metabolites were identified. An isomer of prostaglandin F2 alpha was also excreted intact into the urine as a metabolite of prostaglandin D2. 15 PGF-ring compounds were treated with n-butylboronic acid and 13 failed to form a boronate derivative, suggesting that the orientation of the hydroxyl group at C-11 in these 13 metabolites is beta. This study documents that prostaglandin D2 is metabolized to prostaglandin F-ring metabolites in vivo in humans. These results also bring into question the accuracy of quantifying prostaglandin F2 alpha metabolites as a specific index of endogenous prostaglandin F2 alpha biosynthesis, as well as quantifying urinary prostaglandin F2 alpha as an accurate index of renal production of prostaglandin F2 alpha.     

Identification of metabolites from peroxisomal beta-oxidation of prostaglandins

We have recently shown that isolated rat liver peroxisomes can chain-shorten prostaglandin F2 alpha and prostaglandin E2 to tetranor-metabolites. In the present report dinor-metabolites of these two prostaglandins were also identified, suggesting that the peroxisomal chain-shortening reaction of prostaglandins is a beta-oxidation reaction. Furthermore, an intermediate containing an extra double bond was isolated from incubates of prostaglandin F2 alpha with peroxisomes. This intermediate was tentatively assigned the structure 2,3-dehydroprostaglandin F2 alpha. Prostaglandin E1 and a major circulating prostaglandin F2 alpha metabolite were also metabolized to chain-shortened products by peroxisomes. The accumulation of the 2,3-dehydro-metabolite and the dinor-metabolites suggest that the peroxisomal beta-oxidation sequence is not tightly coupled, in contrast to mitochondrial fatty acid oxidation.     

Metabolism of prostaglandins D2 and F2 alpha in primary cultures of rat hepatocytes

3H-Labeled prostaglandins D2 and F2 alpha rapidly degraded to more-polar metabolites in primary cultured rat hepatocytes. The metabolites of prostaglandins D2 and F2 alpha accumulated in the culture medium. The metabolites extracted by ethyl acetate at pH 3 were purified by silicic acid column and thin-layer chromatography of silica gel, and were analysed by gas chromatography-mass spectrometry. The major metabolites from prostaglandin D2 were identified as dinor-prostaglandin D1 (7 alpha,13-dihydroxy-9-ketodinorprost-11-enoic acid) and tetranor-prostaglandin D1 (5 alpha,11- dihydroxy-7-ketotetranorprost-9-enoic acid). Those from prostaglandin F2 alpha were identified as dinor-prostaglandin F1 alpha (7 alpha,9 alpha,13-trihydroxydinorprost-11-enoic acid), tetranor-prostaglandin F1 alpha (5 alpha,7 alpha,11-trihydroxytetranorprost-9-enoic acid) and 9 alpha,11 alpha,15-trihydroxyprost-13-ene-1,20-dioic acid. These data indicate that prostaglandins D2 and F2 alpha mainly degraded by beta-oxidation, which is the same process as reported earlier for prostaglandins E1 and E2, and that prostaglandin F2 alpha was also subjected to omega-oxidation.     

The degradation of cholic acid by Pseudomonas sp. N.C.I.B. 10590 under anaerobic conditions.

The bacterial degradation of cholic acid under anaerobic conditions by Pseudomonas sp. N.C.I.B. 10590 was studied. The major unsaturated neutral compound was identified as 12 beta-hydroxyandrosta-4,6-diene-3,17-dione, and the major unsaturated acidic metabolite was identified as 12 alpha-hydroxy-3-oxochola-4,6-dien-24-oic acid. Eight minor unsaturated metabolites were isolated and evidence is given for the following structures: 12 alpha-hydroxyandrosta-4,6-diene-3,17-dione, 12 beta,17 beta-dihydroxyandrosta-4,6-dien-3-one, 12 beta-hydroxyandrosta-1,4,6-triene-3,17-dione, 12 beta,17 beta-dihydroxyandrosta-1,4,6-trien-3-one, 12 beta-hydroxyandrosta-1,4,6-triene-3,17-dione, 12 beta,17 beta-dihydroxyandrosta-1,4,6-trien-3-one, 12 alpha-hydroxyandrosta-1,4-diene-3,17-dione, 3-hydroxy-9,10-secoandrosta-1,3,5(10)-triene-9,17-dione, 3,12-dioxochola-4,6-dien-24-oic acid and 12 alpha-hydroxy-3-oxopregna-4,6-diene-20-carboxylic acid. In addition, a major saturated neutral compound was isolated and identified as 3 beta,12 beta-dihydroxy-5 beta-androstan-17-one, and the only saturated acidic metabolite was 7 alpha,12 alpha-dihydroxy-3-oxo-5 beta-cholan-24-oic acid. Nine minor saturated neutral compounds were also isolated, and evidence is presented for the following structures: 12 beta-hydroxy-5 beta-androstane-3,17-dione, 12 alpha-hydroxy-5 beta-androstane-3,17-dione, 3 beta,12 alpha-dihydroxy-5 beta-androstan-17-one, 3 alpha,12 beta-androstan-17-one, 3 alpha,12 alpha-dihydroxy-5 beta-androstan-17-one, 5 beta-androstane-3 beta,12 beta,17 beta-triol, 5 beta-androstane-3 beta,12 alpha,17 beta-triol, 5 beta-androstane-3 alpha,12 beta,17 beta-triol and 5 beta-androstane-3 alpha,12 alpha,17 beta-triol. The induction of 7 alpha-dehydroxylase and 12 alpha-dehydroxylase enzymes is discussed, together with the significance of dehydrogenation and ring fission under anaerobic conditions.     

Metabolic fate of endogenously synthesized prostaglandin D2 in a human female with mastocytosis

Increased production of prostaglandin D2 was recently demonstrated in patients with systemic mastocytosis. One female patient investigated with mastocytosis was found to have overproduction of prostaglandin D2 of such magnitude (150-fold above normal) that it provided the unique opportunity to delineate the metabolic fate of endogenously synthesized prostaglandin D2. A five percent aliquot of a twenty-four hour urine collection from this patient was extracted, purified by silicic acid chromatography, methylated, and finally subjected to high pressure liquid chromatography. Column fractions collected were derivatized and analyzed by gas chromatography-mass spectrometry. Increased quantities of sixteen urinary metabolites were identified and included a series of metabolites retaining the PGD-ring as well as a series of metabolites with a PGF-ring. PGF-ring metabolites were excreted in approximately 4-fold greater relative abundance than PGD-ring metabolites. More than one apparent isomeric form of some PGF-ring metabolites were found. The predominant urinary metabolite was 2,3-dinor-prostaglandin F2. This study provides evidence that endogenously synthesized prostaglandin D2 is converted in substantial part to prostaglandin F2 metabolites in vivo in humans.     

Arachidonic acid metabolic pathways in the rabbit pericardium

Minced rabbit pericardium actively converts [1-14C]arachidonic acid into the known prostaglandins (6-[1-14C]ketoprostaglandin F1 alpha, [1-14C]prostaglandin E2 and [1-14C]prostaglandin F2 alpha) and into several unidentified metabolites. The major metabolite was separated by C18 reverse-phase high-pressure liquid chromatography (HPLC) and identified by gas chromatography-mass spectrometry (GC-MS) to be 6,15-[1-14C]diketo-13,14-dihydroprostaglandin F1 alpha. The other nonpolar metabolites were 15-[1-14C]hydroxy-5,8,11,13-eicosa-tetraenoic acid (15-HETE), 11-[1-14C]hydroxy-5,8,12,14-eicosatetraenoic acid (11-HETE) and 12-[1-14C]hydroxy-5,8,10,14-eicosatetraenoic acid (12-HETE). Arachidonic acid metabolites actively produced by the pericardium could influence the tone of surface blood vessels on the myocardium.     

Metabolism of prostaglandin D2 in isolated rat lung: the stereospecific formation of 9 alpha,11 beta-prostaglandin F2 from prostaglandin D2

The metabolic transformation of exogenous prostaglandin D2 was investigated in isolated perfused rat lung. Dose-dependent formation (2-150 ng) of 9 alpha,11 beta-prostaglandin F2, corresponding to about 0.1% of the perfused dose of prostaglandin D2, was observed by specific radioimmunoassay both in the perfusate and in lung tissue after a 5-min perfusion. To investigate the reason for this low conversion ratio, we analyzed the metabolites of tritium-labeled 9 alpha,11 beta-prostaglandin F2 and prostaglandin D2 by boric acid-impregnated TLC and HPLC. By 5 min after the start of perfusion, 9 alpha,11 beta-prostaglandin F2 disappeared completely from the perfusate and the major product formed remained unchanged during the remainder of the 30-min perfusion. The major product was separated by TLC and identified as 13,14-dihydro-15-keto-9 alpha,11 beta-prostaglandin F2 by GC/MS. In contrast, pulmonary breakdown of prostaglandin D2 was slow and two major metabolites in the perfusate increased with time, each representing 56% and 11% of the total radioactivity at the end of the perfusion. The major product (56%) was identified as 13,14-dihydro-15-ketoprostaglandin D2 and the minor one (11%) was tentatively identified as 13,14-dihydro-15-keto-9 alpha,11 beta-prostaglandin F2 based on the results from radioimmunoassays, TLC, HPLC, and the time course of pulmonary breakdown. These results demonstrate that the metabolism of prostaglandin D2 in rat lung involves at least two pathways, one by 15-hydroxyprostaglandin dehydrogenase and the other by 11-ketoreductase, and that the 9 alpha,11 beta-prostaglandin F2 formed is rapidly metabolized to 13,14-dihydro-15-keto-9 alpha,11 beta-prostaglandin F2.     

Microbial metabolism of steviol and steviol-16alpha,17-epoxide

Steviol (2) possesses a blood glucose-lowering property. In order to produce potentially more- or less-active, toxic, or inactive metabolites compared to steviol (2), its microbial metabolism was investigated. Incubation of 2 with the microorganisms Bacillus megaterium ATCC 14581, Mucor recurvatus MR 36, and Aspergillus niger BCRC 32720 yielded one new metabolite, ent-7alpha,11beta,13-trihydroxykaur-16-en-19-oic acid (7), together with four known related biotransformation products, ent-7alpha,13-dihydroxykaur-16-en-19-oic acid (3), ent-13-hydroxykaur-16-en-19-alpha-d-glucopyranosyl ester (4), ent-13,16beta,17-trihydroxykauran-19-oic acid (5), and ent-13-hydroxy-7-ketokaur-16-en-19-oic acid (6). The preliminary testing of antihyperglycemic effects showed that 5 was more potent than the parent compound (2). Thus, the microbial metabolism of steviol-16alpha,17-epoxide (8) with M. recurvatus MR 36 was continued to produce higher amounts of 5 for future study of its action mechanism. Preparative-scale fermentation of 8 yielded 5, ent-11alpha,13,16alpha,17-tetrahydroxykauran-19-oic acid (10), ent-1beta,17-dihydroxy-16-ketobeyeran-19-oic acid (11), and ent-7alpha,17-dihydroxy-16-ketobeyeran-19-oic acid (13), together with three new metabolites: ent-13,16beta-dihydroxykauran-17-acetoxy-19-oic acid (9), ent-11beta,13-dihydroxy-16beta,17-epoxykauran-19-oic acid (12), and ent-11beta,13,16beta,17-tetrahydroxykauran-19-oic acid (14). The structures of the compounds were fully elucidated using 1D and 2D NMR spectroscopic techniques, as well as HRFABMS. In addition, a GRE (glucocorticoid responsive element)-mediated luciferase reporter assay was used to initially screen the compounds 3-5, and 7 as glucocorticoid agonists. Compounds 4, 5 and 7 showed significant effects.     

Study on the metabolites of 1alpha,25-dihydroxyvitamin D4

Three major metabolites of 1alpha,25-dihydroxyvitamin D(4) were isolated from the bile of rat and the structures were elucidated on the basis of spectral data and the periodate oxidative cleavage of the diol structures of the metabolites. One of the metabolites was the known calcitroic acid. Another two metabolites were isomers and identified as 9,10-secoergosta-5,7,10(19)-triene-1alpha,3beta,24,25-tetrahydroxy-26-oic acid and 9,10-secoergosta-5,7,10(19)-triene-1alpha,3beta,24,25-tetrahydroxy-28-oic acid. It was found that 1alpha,25-dihydroxyvitamin D(4) is metabolized in a similar manner in vivo to that of 1alpha,25-dihydroxyvitamin D(2) but differently from 1alpha,25-dihydroxyvitamin D(3).     

Arachidonic acid metabolism and prostaglandin production by primate preimplantation blastocysts.

Preimplantation embryos of many species are known to synthesize prostaglandins. These tissue hormones are believed to influence embryonic metabolism, as well as embryo-maternal interaction during implantation although their putative role(s) remains obscure. Here, prostaglandin production by blastocysts from cynomolgus monkeys (Macaca fascicularis) was examined qualitatively during in vitro culture. Tritium labelled arachidonic acid was metabolized to 6 keto-prostaglandin F1 alpha, 2,3-dinor-prostaglandin F1 alpha and thromboxane B2, as characterized by HPLC separation. Also, 6-keto-prostaglandin F1 alpha, and thromboxane B2 as characterized by HPLC separation. Also, 6-keto-prostaglandin F1 alpha and thromboxane B2 were identified by specific RIA's. Our data suggest that the main arachidonic acid metabolites produced by blastocysts of cynomolgus monkeys are prostacyclin and thromboxane.     

Novel prostaglandin D(2)-derived activators of peroxisome proliferator-activated receptor-gamma are formed in macrophage cell cultures

Incubation of RAW 264.7 murine macrophages with 9,15-dihydroxy-11-oxo-, (5Z,9alpha,13E,15(S))-Prosta-5,13-dien-1-oic acid [prostaglandin D(2) (PGD(2))] induced formation of considerable peroxisome proliferator-activated receptor-gamma (PPARgamma) activity [Nature 391 (1998) 79]. Because PGD(2) itself is a poor PPARgamma ligand, we incubated RAW 264.7 macrophage cultures with prostaglandin D(2) for 24 h and studied the ability of the metabolites formed to activate PPARgamma. PGD(2) products were extracted and fractionated by reverse phase high-performance liquid chromatography. Chemical identification was achieved by UV spectroscopy, gas-liquid chromatography/mass spectrometry and chemical syntheses of reference compounds. PGD(2) was converted to eight products, six of which were identified. Ligand-induced interaction of PPARgamma with steroid receptor coactivator-1 was determined by glutathione-S-transferase pull-down assays and PPARgamma activation was investigated by transient transfection of RAW 264.7 macrophages. In addition to the previously known ligand 11-oxo-(5Z,9,12E,14Z)-Prosta-5,9,12,14-tetraen-1-oic acid (15-deoxy-delta(12,14)-PGJ(2)), a novel PPARgamma ligand and activator viz. 9-hydroxy-11-oxo-, (5Z,9alpha,12E,14Z)-Prosta-5,12,14-trien-1-oic acid (15-deoxy-delta(12,14)-PGD(2)) was identified. The biological significance of these results is currently under investigation.     

The identification of 5beta,7alpha-dihydroxy-11-oxotetranor-prostane-1,16-dioic acid as a urinary metabolite of prostaglandin F2alpha in the rat.

5beta,7alpha-Dihydroxy-11-oxotetranor-prostane-1,16-dioic acid has been identified by gas chromatography-mass spectrometry as a urinary metabolite of [9beta-3H]prostaglandin F2alpha in the rat. This tetranor prostaglandin F derivative, which is the 5beta epimer of the major urinary metabolite of prostaglandin F2alpha, accounted for at least 2% of the total dose. Absence from the metabolite of tritium label at the C-5 position indicated the existence of a minor, previously unknown metabolic pathway by which prostaglandin Falpha derivatives may be converted by oxido-reduction into prostaglandins of Fbeta stereochemistry.     

Rabbit esophagus metabolizes arachidonic acid predominantly via a lipoxygenase pathway

Eicosanoids modulate the response of gastrointestinal mucosa to noxious stimuli. Though these compounds have been extensively investigated in the stomach, their role in the esophagus has received less attention. Thus, the metabolism of 14C-arachidonic acid by homogenates of rabbit esophageal mucosa was investigated. The major metabolites formed and separated by TLC and HPLC had the chromatographic characteristics of (percent conversion follows each metabolite) 6-keto-prostaglandin F1 alpha (3.80 +/- 1.15), prostaglandin F2 alpha (2.05 +/- 0.37), prostaglandin E2 (5.92 +/- 1.65) and 12-hydroxyeicosatetraenoic acid (26.03 +/- 4.58). Indomethacin, a cyclooxygenase inhibitor, caused a significant decrease in prostaglandin formation without affecting 12-hydroxyeicosatetraenoic acid. BW755C, a combined cyclooxygenase-lipoxygenase inhibitor, dramatically decreased formation of all metabolites. It is concluded that esophageal mucosa metabolizes arachidonic acid primarily to a lipoxygenase derived product. This is the most abundantly produced eicosanoid yet described in the gastrointestinal tract. The importance of this compound to esophageal function is unknown but its presence suggests that future studies of eicosanoids in the esophagus should focus on lipoxygenase metabolites.     

Calcitroic acid is a major catabolic metabolite in the metabolism of 1 alpha-dihydroxyvitamin D(2)

Calcitroic acid (1 alpha-hydroxy-23 carboxy-24,25,26,27-tetranorvitamin D(3)) is known to be the major water-soluble metabolite produced during the deactivation of 1 alpha,25-dihydroxyvitamin D(3). This deactivation process involves a series of oxidation reactions at C(24) and C(23) leading to side-chain cleavage and, ultimately, formation of the calcitroic acid. Like 1 alpha,25-dihydroxyvitamin D(3), 1 alpha,25-dihydroxyvitamin D(2) is also known to undergo side-chain oxidation; however, to date there has been no evidence suggesting that 1 alpha,25-dihydroxyvitamin D(2) undergoes side-chain cleavage. To investigate this possibility, we studied 1 alpha,25-dihydroxyvitamin D(2) metabolism in HPK1A-ras cells as well as the well characterized perfused rat kidney system. Lipid and aqueous-soluble metabolites were prepared for characterization. Aqueous-soluble metabolites were subjected to reverse-phase HPLC analysis. The major aqueous-soluble metabolite from both the kidney and cell incubations comigrated with authentic calcitroic acid on two reverse-phase HPLC columns of different chemistry. The putative calcitroic acid from the cell and kidney incubations was methylated and found to comigrate with methylated authentic standard on straight-phase and reverse-phase HPLC columns. The identity of the methylated metabolite from cell incubations was also confirmed by mass spectral analysis. These data show, for the first time, that calcitroic acid is a major terminal product for the deactivation of 1 alpha,25-dihydroxyvitamin D(2). Intermediates leading to the formation of the calcitroic acid in the 1 alpha,25-dihydroxyvitamin D(2) metabolism pathway are currently being studied.     

Urinary excretion of PGI2/3-M and recent N-6/3 fatty acid intake

Epidemiological studies were performed in a Japanese fishing village when catches of fish were highest and in a Japanese farming village with usual fish consumption. Intake of eicosapentaenoic, docosahexaenoic and also arachidonic acid were significantly higher in the fishing village during the 3 days of the study than in the farming village. The correlation between eicosapentaenoic acid intake on the day when urine was collected and excretion of delta 17-2,3-dinor-6-keto-prostaglandin F1 alpha, the main urinary metabolite of prostaglandin I3, was highly significant, whereas there was no correlation between arachidonic or linoleic acid intake and excretion of 2,3-dinor-6-keto-prostaglandin F1 alpha, the main urinary metabolite of prostaglandin I2. We suggest that the arachidonic acid pool for prostaglandin I2 production is not quickly influenced by dietary linoleic or arachidonic acid because of a large pool size of arachidonic acid and a slow conversion of linoleic acid to arachidonic acid, while prostaglandin I3 formation is directly related to the intake of eicosapentaenoic acid.     

Biosynthesis of 5,6-dihydroxyprostaglandin E1 and F1 alpha from 5,6-dihydroxyeicosatrienoic acid by ram seminal vesicles

cis-5(6)Epoxy-cis-8,11,14-eicosatrienoic acid was recently found to be metabolized by ram seminal vesicles to 5-hydroxyprostaglandin I 1 alpha and 5-hydroxyprostaglandin I 1 beta, 5(6)epoxyprostaglandin E1 and 5,6-dihydroxyprostaglandin E1. The epoxide can be hydrolyzed by epoxide hydrolases to 5,6-dihydroxy-8,11,14-eicosatrienoic acid. The latter was incubated with microsomes of ram seminal vesicles for 2 min at 37 degrees C and the polar metabolites were purified by reversed phase HPLC and analyzed by capillary column gas chromatography-mass spectrometry. The major metabolite was identified as 5,6-dihydroxyprostaglandin F 1 alpha. In the presence of glutathione (1 mM), 5,6-dihydroxyprostaglandin E1 was also formed. The 3H-labelled vicinal diol and the 3H-labelled epoxide were metabolized to polar products to a similar extent, but the formation of prostaglandin E compounds in the presence of glutathione was lower from the diol than from the epoxide or from arachidonic acid. The likely prostaglandin endoperoxide intermediates in the metabolism of the diol (5,6-dihydroxyprostaglandin G1 and 5,6-dihydroxyprostaglandin H1) thus appear to be less prone to be isomerized to prostaglandin E compounds than prostaglandins G2 and H2 and their 5(6)epoxy counterparts. 5(6)Epoxyprostaglandin E1 and 5,6-dihydroxyprostaglandin E1 can be chemically transformed into 5,6-dihydroxyprostaglandin B1. The latter can be analyzed by HPLC or by mass fragmentography, and a simple chemical synthesis of 5,6-dihydroxyprostaglandin B1 from prostaglandin E2 is described.     

Prostaglandin thromboxane, and 12-hydroxy-5,8,10,14-eicosatetraenoic acid production by ionophore-stimulated rat serosal mast cells.

Production of several metabolites of arachidonic acid by purified rat serosal mast cells in response to stimulation with the ionophore A23187 was assessed by stable isotope dilution assay using gas chromatography-mass spectrometry. Compounds quantified were prostaglandins D2, E2, F2 alpha, 6-keto-F1 alpha, thromboxane B2, and 12-hydroxy-5,8,10,14-eicosatetraenoic acid. Mast cells incubated at 37 degrees C for 30 min without ionophore produced measurable quantities of all metabolites assayed. 4 microM A23187 resulted in substantial increased synthesis of all metabolites compared to control cells. Of the metabolites quantified, prostaglandin D2 and prostacyclin were the major products derived from arachidonic acid in ionophore-stimulated rat mast cells.     

Hepatic transformation of prostaglandin D2 to a new prostanoid, 9 alpha,11 beta-prostaglandin F2, that inhibits platelet aggregation and constricts blood vessels

The metabolic transformation of tritium-labeled prostaglandin D2 ([3H]PGD2) was investigated in the isolated Tyrode's-perfused rabbit liver. One major product was isolated and identified in the perfusate as a new prostanoid. The structure of this metabolite was further confirmed by gas chromatography-mass spectrometry and chemical methods to be 9 alpha,11 beta,15-L-trihydroxyprosta-5-cis, 13-trans-dienoic acid, namely (9 alpha,11 beta-PGF2). This new prostanoid was found to be an inhibitor of platelet aggregation and to cause constriction of canine coronary artery strips. These results suggested that on passage through the hepatic circulation exogenous PGD2 is converted to 9 alpha,11 beta-PGF2, the latter having a biological profile which differs from that of PGD2 and PGF2 alpha.     

Disturbance of pulmonary prostaglandin metabolism in fetuses of alloxan-diabetic rabbits

[14C]Arachidonic acid conversion in lung homogenates of 28-day fetuses from control and alloxan-diabetic rabbits was studied. The major metabolites were 12-L-hydroxy-5,8,10,14-eicosatetraenoic acid and prostaglandin E2. Small amounts of 6-ketoprostaglandin F1 alpha, prostaglandin F2 alpha, and thromboxane B2 were also observed. Lung homogenates from fetuses of alloxan-diabetic rabbits convert significantly less [14C]arachidonic acid to prostaglandin E2, whereas all other metabolites were present in similar quantities compared to fetuses of non-diabetic rabbits. These studies suggest that the decreased arachidonic acid conversion to prostaglandin E2 could be partially responsible for the functional delay of lung maturation in offspring of alloxan-diabetic rabbits.     

Characterization of arachidonic acid metabolic profiles in animal tissues by high-resolution gas chromatography-mass spectrometry

A standardized, highly specific routine method was developed for the quantitative profiling of cyclooxygenase metabolites of arachidonic acid in animal tissues. Whole homogenates were used to assess the potential capacity of tissues to metabolize endogenous arachidonic acid. Samples were analyzed by high-resolution gas chromatography-mass spectrometry in the selected ion monitoring mode. The screening of several rat tissues by this method revealed marked tissue-specificity in both the synthesis capacity and prostaglandin profile. The major products detected were: 6-ketoprostaglandin F1alpha for lung, stomach, muscle and heart; prostaglandin D2 for spleen, brain and liver; prostaglandin F2alpha for kidney and prostaglandin E2 for seminal vesicles. Marked species differences were found when guinea pig tissues were analyzed.