6-Ketoprostaglandin F1 alpha, prostaglandins E2, F2 alpha and thromboxane B2 production by endothelial cells, smooth muscle cells and fibroblasts cultured from piglet aorta

After [3H]arachidonic acid labeling, cyclooxygenase products were qualitatively analysed in the media of each cultured vascular cell type by reverse-phase high-performance liquid chromatography (rp-HPLC). The prostaglandin E2, prostaglandin F2 alpha, 6-ketoprostaglandin F1 alpha and thromboxane B2 detected in the rp-HPLC radioactive profile were then quantified by radioimmunoassay (RIA) in separate sets of experiments. In preconfluent endothelial cells prostaglandin F2 alpha and 6-ketoprostaglandin F1 alpha were detected in equal amounts (49%), whereas after confluence 6-ketoprostaglandin F1 alpha represented 57% of total secretion (P less than 0.05). Smooth muscle cells secreted mainly prostaglandin F2 alpha (48%) and fibroblasts prostaglandin E2 (44%). Using the bioassay method, antiaggregatory activity was detected only in endothelial cells, though a small percentage of immunoreactive 6-ketoprostaglandin F1 alpha was encountered in smooth muscle cells and fibroblasts (13 and 10%, respectively). Radioimmunological analysis after rp-HPLC separation of the medium of endothelial cells showed that the anti-6-ketoprostaglandin F1 alpha antibody recognized, among other substances, an unidentified compound. Its retention time was similar to that of prostaglandin F2 alpha. This unidentified compound was not detected in the media from smooth muscle cells and fibroblasts.     

Induction of prostacyclin formation by sodium n-butyrate in a cloned epithelial liver cell line

The effect of sodium n-butyrate on prostaglandin synthesis in cultured cells was examined. Exposure of BC-90 cells, a clone of an epithelial rat liver cell line, to 1 mM sodium n-butyrate for 40 h induced prostacyclin production. Prostacyclin synthesis was proved by demonstrating: (1) production of labeled 6-ketoprostaglandin F1 alpha by treating [14C]arachidonic acid pre-labeled cells with calcium ionophore A23187, (2) production of unstable substance that inhibited adenosine diphosphate-induced platelet aggregation, and (3) conversion of [14C]arachidonic acid to 6-ketoprostaglandin F1 alpha in homogenates of n-butyrate-treated cells. Untreated control cells showed negligible prostaglandin synthesis. Untreated cell homogenates did not convert [14C]arachidonic acid to any prostaglandins, but they converted [14C]prostaglandin H2 to prostacyclin. Induction of prostacyclin production by n-butyrate was also demonstrated with cells that had been treated with acetylsalicylic acid before n-butyrate treatment in acetylsalicylic acid-free medium. Incorporation of [3H]acetylsalicylic acid by sodium n-butyrate-treated cells increased in accordance with treatment time, while that of untreated cells did not change during culture. There was no difference in the phospholipase A2 activities of n-butyrate-treated and -untreated cells. From these findings, the possibility that n-butyrate induced prostacyclin in BC-90 cells through induction of fatty acid cyclooxygenase activity is discussed.     

Macrophage eicosanoid formation is stimulated by platelet arachidonic acid and prostaglandin endoperoxide transfer

The present study was designed to determine whether platelets transfer arachidonic acid or prostaglandin endoperoxide intermediates to macrophages which may be further metabolized into cyclooxygenase products. Adherent peritoneal macrophages were prepared from rats fed either a control diet or an essential fatty acid-deficient diet, and incubated with a suspension of washed rat platelets. Macrophage cyclooxygenase metabolism was inhibited by aspirin. In the presence of a thromboxane synthetase inhibitor, 7-(1-imidazolyl)heptanoic acid, immunoreactive 6-ketoprostaglandin F1 alpha formation was significantly increased 3-fold. Since this increase was greater (P less than 0.01) than that seen with either 7-(1-imidazolyl)heptanoic acid-treated platelets or aspirin-treated macrophages alone, these results indicate that shunting of endoperoxide from platelets to macrophages may have occurred. In further experiments, macrophages from essential fatty acid-deficient rats were substituted for normal macrophages. Essential fatty acid-deficient macrophages, depleted of arachidonic acid, produced only 2% of the amount of eicosanoids compared to macrophages from control rats. When platelets were exposed to aspirin, stimulated with thrombin, and added to essential fatty acid-deficient macrophages, significantly more immunoreactive 6-ketoprostaglandin F1 alpha was formed than in the absence of platelets. This increased macrophage immunoreactive 6-ketoprostaglandin F1 alpha synthesis, therefore, must have occurred from platelet-derived arachidonic acid. These data indicate that in vitro, in the presence of an inhibition of thromboxane synthetase, prostaglandin endoperoxides, as well as arachidonic acid, may be transferred between these two cell types.     

Radioimmunologic identification of prostaglandins produced by serum-stimulated mouse embryo palate mesenchyme cells

High-performance liquid chromatography and radioimmunoassay were used to identify the prostaglandins synthesized by mouse embryo palate mesenchyme cells. Serum stimulated the release of several different metabolites of arachidonic acid including 6-ketoprostaglandin F1 alpha (the stable product of prostacyclin, prostaglandin I2), prostaglandin E2 and prostaglandin F2 alpha. Compared to control cells, the serum-stimulated cells produce elevated levels of prostaglandin E2 (36-fold), 6-ketoprostaglandin F1 alpha (15-fold) and prostaglandin F2 alpha (7-fold). The acetylenic analogue of arachidonic acid, 5,8,11,14-eicosatetraynoic acid prevented this accelerated synthesis.     

Production of arachidonic acid metabolites by endothelial cells in hyperoxia

This study investigated the response of bovine pulmonary artery endothelial cells to incubation in hyperoxia (95% O2-5% CO2). Changes in cell number and morphology, release of lactate dehydrogenase, and production of arachidonic acid metabolites were assessed during continuous exposure of confluent endothelial monolayers to air (air-5% CO2, "controls") or O2 (95% O2-5% CO2, "O2-exposed") for periods of 12-72 h. Control monolayer cell numbers remained constant (approximately 2,000,000 cells/flask), whereas the number of cells in O2-exposed monolayers decreased progressively to 30% of controls (P less than 0.01) by 72 h. As assessed by radioimmunoassay, both control and O2-exposed cells produced the prostacyclin metabolite, 6-ketoprostaglandin F1 alpha (6-keto-PGF1 alpha), and prostaglandin F2 alpha (PGF2 alpha), but no thromboxane metabolite (TxB2) was detected. The O2-exposed cells released significantly more 6-keto-PGF1 alpha and PGF2 alpha than control cells when apparent net production rates over the entire 72-h period were compared. In addition, both control and O2-exposed (48 h) endothelial monolayers released immunoreactive leukotriene B4 (LTB4) on stimulation with calcium ionophore (10 microM A23187). As with the cyclooxygenase products, O2-exposed cells released more immunoreactive LTB4 than did controls. Both cyclooxygenase and lipoxygenase metabolites of arachidonic acid are released by cultured endothelial cells during the development of O2 toxicity.     

Prostaglandin I2 synthesis and elevation of cyclic AMP levels in 3T3 fibroblasts

Arachidonic acid and prostaglandin H2 elevate the levels of adenosine 3':5'-monophosphate (cyclic AMP) in Balb/c 3T3 fibroblasts. This effect was inhibited by 15-hydroperoxy-5,8,11,13-eicosatetraenoic acid, an inhibitor of prostaglandin I2 synthase (Claesson, H.-E., Lindgren, J.A. and Hammarstr!om, S. (1977) FEBS Lett. 81, 415-418). After addition of arachidonic acid to 3T3 cultures, cellular cyclic AMP levels and growth medium concentrations of 6-ketoprostaglandin F1 alpha (degradation product of prostaglandin I2) were quantitatively determined. The stimulatory effect of exogenously-added prostaglandin I2 on cellular cyclic AMP levels was also determined. The results indicate that the endogenous production of prostaglandin I2 is sufficient to explain the stimulatory action of arachidonic acid on cyclic AMP formation in 3T3 fibroblasts.     

Effect of in vitro aging on 6-ketoprostaglandin F1 alpha-producing activity in cultured human diploid lung fibroblasts.

Prostaglandin synthesis in human diploid fibroblasts was studied by incubating [14C]-arachidonic acid with cell homogenates. The majority of prostaglandins produced in young cells was 6-ketoprostaglandin F1 alpha. The 6-ketoprostaglandin F1 alpha-producing activity of cultures declined with in vitro aging, and was almost undetectable at the senescent stage, while total production of thromboxane B2, prostaglandin F2 alpha and prostaglandin E2-like metabolites increased with in vitro aging.     

Comparison of arachidonic acid metabolism between myofibroblasts and fibroblasts isolated from rat palatal mucoperiosteum

Myofibroblasts were cultured successfully from experimental wound tissue in rat palatal mucoperiosteum. Arachidonic acid metabolizing activity in cultured myofibroblasts was compared with that in fibroblasts cultured from normal mucoperiosteum. Prostaglandins biosynthesized from [14C]arachidonic acid in cell-free homogenates of both myofibroblasts and fibroblasts were prostaglandins D2, E2 and F2 alpha, and the activity producing each prostaglandin was not significantly different between the myofibroblasts and the fibroblasts, whereas smooth muscle cells, which are histologically similar to myofibroblasts, produced mainly 6-ketoprostaglandin F1 alpha, and relatively small amounts of prostaglandin E2. The release of arachidonic acid from cells prelabeled with [14C]arachidonic acid was compared among three types of cell. The calcium ionophore A23187 strongly enhanced arachidonic acid release in all three cell types. Bradykinin, 5-hydroxytryptamine and prostaglandin F2 alpha affected the stimulation of arachidonic acid release in the fibroblasts but were less or not effective in the myofibroblasts and smooth muscle cells. In addition, prostaglandin E2 biosynthesized in response to several stimuli was measured by radioimmunoassay. The content of prostaglandin E2 correlated closely with arachidonic acid release. In this study, we showed homogeneity between the myofibroblasts and fibroblasts in prostaglandin synthesizing activity and similarity in response to various stimuli between the myofibroblasts and smooth muscle cells, from the standpoint of arachidonic acid metabolism.     

Regional differences in prostacyclin formation by the kidney. Prostacyclin is a major prostaglandin of renal cortex.

Microsomes prepared from rabbit renal cortex were found to synthesize substantial amounts of 6-ketoprostaglandin F1alpha from prostaglandin G2 or arachidonic acid during an incubation. In contrast, no 6-ketoprostaglandin F1alpha was formed by renal medullary microsomes which synthesize predominantly prostaglandin E2. Mass spectral confirmation of the structure of 6-ketoprostaglandin F1alpha from these incubations demonstrates the ability of the renal cortex to synthesize prostacyclin.     

Formation of 11-hydroxyeicosatetraenoic acid and 15-hydroxyeicosatetraenoic acid in human umbilical arteries is catalyzed by cyclooxygenase

Human umbilical arteries convert arachidonic acid into three hydroxy-eicosatetraenoic acids as well as 6-ketoprostaglandin F1 alpha, prostaglandins E2, F2 alpha and D2 and thromboxane B2. Two of these hydroxy derivatives of arachidonic acid were purified by reverse-phase HPLC and identified by GC-MS as 11-hydroxyeicosatetraenoic acid (11-HETE) and 15-hydroxyeicosatetraenoic acid (15-HETE) while a third, presumed dihydroxy derivative has not yet been identified. Both the cyclooxygenase and HETE synthesizing activities were found to be localized mainly in the microsomal fraction (100 000 X g pellet) (51 and 61% of total, respectively), and approx. 25% of both activities was found in the 10 000 X g pellet. The formation of these HETEs was inhibited by the cyclooxygenase inhibitors indomethacin and aspirin but not by the lipoxygenase inhibitor nordihydroguaiaretic acid. Production of immunoreactive 15-HETE as well as 6-ketoprostaglandin F1 alpha were also decreased significantly when arterial segments were incubated in the presence of either indomethacin or aspirin. Indomethacin inhibited the formation of both prostanoids and HETEs by microsomes in a concentration-dependent and time-dependent manner. The ID50 values for indomethacin against HETE synthesizing activity and against cyclooxygenase were 4.5 and 3.8 microM, respectively. The inactivation constants were found to be 0.09 and 0.08 min-1 for HETE synthesizing activity and cyclooxygenase, respectively. These two microsomal activities were solubilized in parallel with Tween-20. Incubation with three distinct monoclonal antibodies against different epitopes on cyclooxygenase precipitated both cyclooxygenase and HETE synthesizing activity. Each of these activities was recovered in the immune pellets. These studies demonstrate that in human umbilical arteries 11-HETE, 15-HETE and a presumed di-HETE are the products of cyclooxygenase.     

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.     

Comparison of the production of eicosanoids by human and rat peritoneal macrophages and rat Kupffer cells

Human and rat peritoneal macrophages and rat Kupffer cells were labelled with [1-14C] arachidonic acid and stimulated with the calcium ionophore A23187. The metabolites formed were separated by high pressure liquid chromatography (HPLC). Human peritoneal macrophages formed especially leukotriene B4, 5-hydroxy-6,8,11,14 eicosatetraenoic acid and small amounts of leukotriene C4 and thromboxane B2, 12-hydroxy-5,8,10 heptadecatrienoic acid and 6-keto-prostaglandin F1 alpha, whereas rat peritoneal macrophages mainly produced cyclooxygenase products and in particular thromboxane B2 and 12-hydroxy-5,8,10 heptadecatrienoic acid. Rat Kupffer cells synthesized mainly cyclooxygenase products such as prostaglandin F2 alpha, prostaglandin D2 and prostaglandin E2. These results indicate that the profile of eicosanoids production by macrophages is dependent both on the species and on the tissue from which the macrophage is derived.     

Possible inhibitory function of endogenous 15-hydroperoxyeicosatetraenoic acid on prostacyclin formation in bovine aortic endothelial cells

Arachidonic acid is metabolized via the cyclooxygenase pathway to several potent compounds that regulate important physiological functions in the cardiovascular system. The proaggregatory and vasoconstrictive thromboxane A2 produced by platelets is opposed in vivo by the antiaggregatory and vasodilating activity of prostacyclin (prostaglandin I2) synthesized by blood vessels. Furthermore, arachidonic acid is metabolized by lipoxygenase enzymes to different isomeric hydroxyeicosatetraenoic acids (HETE's). This metabolic pathway of arachidonic acid was studied in detail in endothelial cells obtained from bovine aortae. It was found that this tissue produced 6-ketoprostaglandin F1 alpha as a major cyclooxygenase metabolite of arachidonic acid, whereas prostaglandins F2 alpha and E2 were synthesized only in small amounts. The monohydroxy fatty acids formed were identified as 15-HETE, 5-HETE, 11-HETE and 12-hydroxy-5,8,10-heptadecatrienoic acid (HHT). The latter two compounds were produced by cyclooxygenase activity. Nordihydroguaiaretic acid (NDGA), a rather selective lipoxygenase inhibitor and antioxidant blocked the synthesis of 15- and 5-HETE. It also strongly stimulated the cyclooxygenase pathway, and particularly the formation of prostacyclin. This could indicate that NDGA might exert its effect on prostacyclin levels by preventing the synthesis of 15-hydroperoxyeicosatetraenoic acid (15-HPETE), a potent inhibitor of prostacyclin synthetase. 15-HPETE could therefore act as an endogenous inhibitor of prostacyclin production in the vessel wall.     

In vitro inhibition of prostaglandin production by azathioprine and 6-mercaptopurine

Although there are many data concerning the cytotoxic and immunosuppressive effects of antimetabolites such as azathioprine and 6-mercaptopurine, the mechanism of their antiinflammatory action has not been extensively investigated. In the present work, it is shown that azathioprine and 6-mercaptopurine (10-500 micrograms/ml) inhibit in a dose-dependent manner the production of PGE2, PGF2 alpha, 6-keto-PGF1 alpha and TXB2 by unseparated spleen cells as well as that of 6-keto-PGF1 alpha by adherent peritoneal macrophages. This inhibitory effect appears rapidly in vitro (within 15 min of incubation) and is observed in the presence of exogenous arachidonic acid (5 x 10(-6) M). The persistence of this effect in the presence of arachidonic acid, together with the fact that the production of four cyclooxygenase derivatives of acid arachidonic metabolism are inhibited, suggests that these drugs are acting at the cyclooxygenase level. The finding that cytotoxic and immunosuppressive agents, which act mainly by inhibiting RNA and DNA synthesis, can block prostaglandin production, may explain part of their antiinflammatory effects.     

Appearance of the arachidonic acid metabolic pathway in human promyelocytic leukemia (HL-60) cells during monocytic differentiation: enhancement of thromboxane synthesis by 1 alpha,25-dihydroxyvitamin D-3

The appearance of the arachidonic acid metabolic pathway in human promyelocytic leukemia (HL-60) cells was investigated during 1 alpha,25-dihydroxyvitamin D-3-induced monocytic differentiation. 1 alpha,25-Dihydroxyvitamin D-3-treated HL-60 cells acquired the ability to convert [1-14C]arachidonic acid to thromboxane B2 and prostaglandin E2 during monocytic differentiation. The major cyclooxygenase product synthesized by the HL-60 cells after 3-4 days exposure to 1 alpha,25- dihydroxyvitamin D-3 (48 nM) was thromboxane B2 and its production was about 19-25-times higher than that of untreated HL-60 cells. The percent conversion of thromboxane B2 from [1-14C]arachidonic acid in the 1 alpha,25-dihydroxyvitamin D-3 (48 nM, 3 day exposure)-treated HL-60 cells was about 4.4% as compared to that (about 0.3%) of the untreated cells, whereas the percent conversion of thromboxane B2 from [1-14C]prostaglandin H2 in the 1 alpha,25-dihydroxyvitamin D-3-treated cell homogenate was about 22.4% as compared to that (about 13.6%) of the untreated cell homogenate. The stimulatory effect of 1 alpha,25-dihydroxyvitamin D-3 on thromboxane B2 production from [1-14C]arachidonic acid and from [1-14C]prostaglandin H2 in HL-60 cells was inhibited by the addition of cycloheximide (1 microgram/ml). However, 1 alpha,25-dihydroxyvitamin D-3 (48 nM) did not significantly stimulate the arachidonic acid release either in HL-60 cells or in 1 alpha,25-dihydroxyvitamin D-3-induced cells. These results suggest that the stimulatory effect of 1 alpha,25-dihydroxyvitamin D-3 on the thromboxane production in HL-60 cells was not due to the activation of phospholipase A2 but due to the induction of fatty acid cyclooxygenase and thromboxane synthetase activities. Thromboxane A2 actively produced during the monocytic differentiation of HL-60 cells could influence the cell adhesiveness of the monocyte-macrophage-differentiated cells.     

Edema from cyclooxygenase products of endogenous arachidonic acid in isolated lung

We infused A23187, a calcium ionophore, into the pulmonary circulation of dextran-salt-perfused isolated rabbit lungs to release endogenous arachidonic acid. This led to elevations in pulmonary arterial pressure and to pulmonary edema as measured by extravascular wet-to-dry weight ratios. The increase in pressure and edema was prevented by indomethacin, a cyclooxygenase enzyme inhibitor, and by 1-benzylimidazole, a selective inhibitor of thromboxane (Tx) A2 synthesis. Transvascular flux of 125I-albumin from vascular to extravascular spaces of the lung was not elevated by A23187 but was elevated by infusion of oleic acid, an agent known to produce permeability pulmonary edema. We confirmed that A23187 leads to elevations in cyclooxygenase products and that indomethacin and 1-benzylimidazole inhibit synthesis of all cyclooxygenase products and TxA2, respectively, by measuring perfusate levels of prostaglandin (PG) I2 as 6-ketoprostaglandin F1 alpha, PGE2, and PGF2 alpha and TxA2 as TxB2. We conclude that release of endogenous pulmonary arachidonic acid can lead to pulmonary edema from conversion of such arachidonic acid to cyclooxygenase products, most notably TxA2. This edema was most likely from a net hydrostatic accumulation of extravascular lung water with an unchanged permeability of the vascular space, since an index of permeability-surface area product (i.e., transvascular albumin flux) was not increased.     

Bradykinin produces pulmonary vasodilation in fetal lambs: role of prostaglandin production

Bradykinin produces pulmonary vasodilation and also stimulates production of other pulmonary vasodilators, including prostaglandin I2 (PGI2) and endothelial-derived relaxing factor. In 12 chronically instrumented fetal lambs, we therefore investigated potential mediation of the bradykinin response by PGI2 or other cyclooxygenase products. A 15-min infusion of bradykinin (approximately 1 microgram/kg estimated fetal wt/min) increased fetal pulmonary blood flow by 522% (P less than 0.05) and decreased pulmonary vascular resistance by 86% (P less than 0.05); plasma 6-ketoprostaglandin F1 alpha (6-keto-PGF1 alpha) concentration also increased (P less than 0.05). After cyclooxygenase inhibition by indomethacin (3 mg), bradykinin increased pulmonary blood flow by only 350% (P less than 0.05) and decreased pulmonary vascular resistance by 83% (P less than 0.05); plasma 6-keto-PGF1 alpha concentrations did not increase. The increase in pulmonary blood flow produced by bradykinin was greater before administration of indomethacin than after (P less than 0.05). These studies demonstrate that bradykinin produces fetal pulmonary vasodilation by at least two mechanisms, one dependent on and the other independent of PGI2 production, the latter mechanism predominating.     

Culture of mesothelial cells from bovine pericardium and characterization of their arachidonate metabolism

Cultures of mesothelial cells from bovine pericardium were established and their arachidonate metabolism was characterized. The identification of the cultured cells was based on morphological observations, and by electrophoretic analysis of cytoskeletal proteins, which demonstrated a pattern previously reported for mesothelial cells. Factor VIII-related antigen was present by indirect immunofluorescence, but the cells had no thrombomodulin activity. The cultured pericardial cells metabolized arachidonic acid to 6-ketoprostaglandin F1 alpha and a small amount of prostaglandin E2. The same metabolites were produced by pieces of intact parietal pericardium but not by pieces from which mesothelium had been removed. The cultured mesothelial cells produced 94.6 +/- 60.4 (mean +/- S.D.) ng/mg (n = 3) cell protein of 6-ketoprostaglandin F1 alpha in response to the calcium ionophore A23187, 117.3 +/- 13.6 ng/mg (n = 3) with exogenous arachidonic acid, 18.3 +/- 11.3 ng/mg (n = 5) with bradykinin, 8.4 +/- 4.3 ng/kg (n = 4) with histamine and 11.2 +/- 9.7 ng/mg (n = 5) with thrombin. All of these values were significantly higher (P less than 0.05) than the control (2.1 +/- 1 ng/mg; n = 5). From these results, we conclude that the mesothelial cells account for the arachidonate metabolism in the pericardium. The production of prostaglandin I2 occurs in response to physiological or pathological, agonists, and is substantial. That is, it is approximately the same as endothelial cells. The release of eicosanoids by mesothelial cells into the pericardial space may have a significant role in cardiac physiology and pathology.     

Release of prostaglandins and thromboxanes by guinea pig isolated type II pneumocytes

Lung cells have been isolated by enzymatic digestion of guinea pig lungs and mechanical dispersion to obtain a suspension of viable cells (approximately 500 X 10(6) cells). Type II pneumocytes have been purified to approximately 92% by centrifugal elutriation (2000 rpm, 15 ml/min) followed by a plating in plastic dishes coated with guinea pig IgG (500 micrograms/ml). We have investigated the arachidonic acid metabolism through the cyclooxygenase pathway in this freshly isolated type II cells (2 x 10(6) cells/ml). Purified type II pneumocytes produced thromboxane B2 (TxB2) predominantly and to a smaller extent the 6-keto prostaglandin PGF1 alpha (6-keto-PGF1 alpha) and prostaglandin E2 (PGE2) after incubation with 10 microM arachidonic acid. The stimulation of pneumocytes with 2 microM calcium ionophore A23187 released less eicosanoids than were produced when cells were incubated with 10 microM arachidonic acid. There was no additive effect when the cells were treated with both arachidonic acid and the ionophore A23187. Guinea pig type II pneumocytes failed to release significant amounts of TxB2, 6-keto-PGF1 alpha and PGE2 after stimulation with 10 nM leukotriene B4, 10 nM leukotriene D4, 10 nM platelet-activating factor, 5 microM formyl-methionyl-leucyl-phenylalanine, 0.2 microM bradykinin and 10 nM phorbol myristate acetate. Our findings indicate that guinea pig type II pneunomocytes possess the enzymatic machinery necessary to convert arachidonic acid to specific cyclooxygenase products, which may suggest a role for these cells in lung inflammatory processes.     

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.