The aim of our study was to examine the release of various lipid and peptide contracting autacoids by aortae of normal and atherosclerotic rabbits. Leukotriene (LT) E4, an enzymatic derivative of LTC4, thromboxane (Tx) B2, and endothelin-1 (ET-1) were measured by radioimmunoassay techniques in aortic preparations of normal and cholesterol-fed rabbits. Intact aortae of normal rabbits incubated with the calcium ionophore A23187 for 1 h at 37 degrees C released LTE4 and TxB2 (22 +/- 3.5 and 14.8 +/- 2 pg/mg of tissue, respectively, mean +/- SEM, n = 33). Removal of aortic endothelium was associated with a significant reduction in LTE4 (44%) and TxB2 (58%) release. In aortic preparations from cholesterol-fed rabbits, the release of LTE4 was significantly enhanced (41 +/- 8 pg/mg of tissue, mean +/- SEM, n = 27) whereas TxB2 was not significantly altered. No detectable amounts of ET-1 were measured after 1 h of incubation. However, at 4 h, an endothelium-dependent release of ET-1 from normal aortae was demonstrated. In atherosclerotic aortae, ET-1 release was significantly higher than in controls (10 +/- 1.3 vs. 5 +/- 0.5 pg/cm2, mean +/- SEM, n = 16). We conclude that enhanced formation of vasoconstrictor autacoids may contribute to altered vasomotion of atherosclerotic blood vessels.

The guinea-pig lung parenchymal (GPLP) strip is sensitive to leukotrienes (LT) C4 and D4 (LTC4 and LTD4). These substances induce contractions during which thromboxane (TX) A2 (TxA2) is released. This event was measured both by bioassay of TxA2 and radioimmunoassay of thromboxane B2 (TxB2). Indomethacin partially inhibited the contractile response and completely abolished the release of TxA2. The proportional participation of TxA2 in the contractile response was calculated quantitatively, and appeared to be 70-90%. On basis of these results, it is concluded that only a small proportion of the contractions is due to the direct action of the leukotrienes and a major part to the formed thromboxane A2. The action of the phospholipase A2 (PLA2) inhibitor chloroquine and the phosphodiesterase inhibitor, 3-isobutyl-1-methyl-xanthine (IBMX), were measured both on the contraction and the TxA2 release. Chloroquine in a dose of 40 /micrograms/ml totally inhibited the TxA2 release induced by 50 ng LTD4. At higher doses, the contractions were also completely inhibited. IBMX in a dose of 22 /micrograms/ml inhibited both the contraction and the TxA2 release to a large extent. These effects are most probably due to an inhibition of the phospholipase A2 which is activated by the leukotrienes. It is supposed that chloroquine acts directly and that the action of IBMX is due to an increase in cyclic AMP, which also leads to an inhibition of the enzyme. After the incubation of lung strips with [1-14C] arachidonic acid (AA), mainly TxB2 and lipoxygenase products are formed.

This double-blind, randomized crossover study assessed the effect of acetaminophen (1000 mg every 8 hours) versus indomethacin (50 mg every 8 hours) versus placebo on cyclooxygenase enzymes (COX-1 and COX-2). Urinary excretion of 2,3-dinor-6-keto-PGF1α, (prostacyclin metabolite, PGI-M; COX-2 inhibition) and 11-dehydro thromboxane B2 (thromboxane metabolite, Tx-M; COX-1 inhibition) were measured after 1 dose and 5 days of dosing. Peak inhibition of urinary metabolite excretion across 8 hours following dosing was the primary end point. Mean PGI-M excretion was 33.7%, 55.9%, and 64.6% on day 1 and 49.4%, 65.1%, and 80.3% on day 5 (placebo, acetaminophen, and indomethacin, respectively). Acetaminophen and indomethacin inhibited PGI-M excretion following single and multiple doses (P = .004 vs placebo). PGI-M excretion inhibition after 1 dose was similar for indomethacin and acetaminophen, but significantly greater with indomethacin after multiple doses (P = .006). Mean Tx-M excretion was 16.2%, 45.2%, and 86.6% on day 1 and 46.2%, 58.4%, and 92.6% on day 5 (placebo, acetaminophen, and indomethacin, respectively). Tx-M excretion inhibition following 1 dose was reduced by acetaminophen (P ≤ .003). Indomethacin reduced Tx-M excretion significantly more than acetaminophen and placebo after single and multiple doses (P ≤ .001). Acetaminophen and indomethacin inhibited COX-1 and COX-2 following a single dose, but acetaminophen was a less potent COX-1 inhibitor than indomethacin.

Lungs from guinea pigs passively sensitized with an affinity-purified IgG1 antibody produce both leukotriene (LT)D4 and thromboxane (Tx)B2 upon ex vivo antigen challenge. This study was undertaken to determine the possibility of endogenously generated peptido-LTs being a prerequisite for Tx synthesis. In immunoglobulin G1-sensitized lungs, exogenous LTD4 induced TxB2 production with a median effective dose of 4.1 nM, whereas the response to LTE4, LTB4 or platelet-activating factor was relatively weak. Although LTC4 was as potent as LTD4 in stimulating TxB2 generation, LTC4's dose-response curve was shifted significantly to the right by AT-125, an irreversible gamma-glutamyl transpeptidase inhibitor, suggesting that at least a part of LTC4 sensitized lungs with antigen (0.01-30 micrograms/ml ovalbumin) for 20 min precipitated a significant amount of LTD4 production. The levels of LTD4 range from 8 to 26 nM (without taking LTD4 recovery into consideration). This level is 2- to 7-fold greater than the median effective dose value observed with exogenous LTD4. Moreover, pretreatment of sensitized lungs with ICI-198,615 a specific LTD4 antagonist, blocked equally both antigen (IC50 = 0.01 microM)- and LTD4 (IC50 = 0.017 microM)-induced TxB2 production. When sensitized lung fragments were treated with 5 mM AT-125, ICI-198,615 was effective in preventing not only antigen-but also LTC4-dependent production of TxB2 (IC50 = 0.018 and 0.021 microM, respectively). In contrast, neither WEB-2086, a platelet-activating factor antagonist, nor pyrilamine, a histamine antagonist, inhibited antigen and LTD4 responses (IC50 greater than 30 microM). Unlike its effect on antigen response, ICI-198,615 was unable to block Ca2+ ionophore-induced TxB2 production.2

The effect of azelastine on platelet-activating factor (PAF)-induced bronchoconstriction and mediator release in isolated lungs from actively sensitised guinea-pigs was investigated. Guinea-pigs were actively sensitised with two s.c. injections of 10 micrograms ovalbumin in 1 mg Al (OH)3 at a 2-week interval. One week after the second injection, the lungs were removed and challenged intra-arterially with PAF or arachidonic acid. In some experiments lungs from non-immunised guinea-pigs were injected with PAF or histamine. Bronchoconstriction, the release of thromboxane (TX)B2 or leukotriene (LT)-like material and the histamine content of the effluent were evaluated. Azelastine was given s.c. at 10 or 100 micrograms/kg, 4 h before lung removal. Azelastine (100 micrograms/kg) did not inhibit PAF-induced bronchoconstriction and mediator release from lungs from non-immunised guinea-pigs. In contrast, the hyperresponsiveness to 1 ng PAF observed in lungs from actively sensitised animals was dose dependently inhibited by azelastine. Azelastine did not reduce the histamine-induced bronchoconstriction and consequent TXB2 release from lungs from immunised guinea-pigs, indicating that the protective effect exerted against hyperresponsiveness to PAF was not due to histamine antagonism. Azelastine also reduced arachidonic acid-induced bronchoconstriction and LT-like material release from sensitised lungs, regardless of the presence of indomethacin. These results suggest that inhibition of lung hyperresponsiveness to PAF by azelastine may result from an interference with leukotriene synthesis.

Alterations of phospholipid and arachidonic acid metabolism were studied by treatment of guinea-pig peritoneal-exudate macrophages with chemotactic peptide, formylmethionyl-leucylphenylalanine (fMet-Leu-Phe) and macrophage activation factor (MAF). The chemotactic peptide caused a rapid rearrangement in inositol phospholipids, including a breakdown of polyphosphoinositides within 30s, followed by a resultant formation of phosphatidylinositol (PI), diacylglycerol, phosphatidic acid and non-esterified arachidonic acid within 5 min. In addition to these sequential alterations, arachidonic acid was released mainly from PI. On the other hand, MAF induced a slow liberation of arachidonic acid, mainly from phosphatidylethanolamine (PE) and phosphatidylcholine (PC) by phospholipase A2 after the incubation period of 30 min, but not any rapid changes in phospholipids. Treatment of macrophages for 15 min with fMet-Leu-Phe produced the leukotrienes (LTs) B4, C4 and D4, prostaglandins (PG) E2 and F2 alpha and thromboxane (TX) B2. In contrast, MAF could not stimulate the production of arachidonic acid metabolites during the incubation period of 15 min, but could enhance that of PGE2, PGF2 alpha, TXB2 and hydroxyeicosatetraenoic acids at 6 h. However, the stimulated formation of LTs was not detected at any time. These results indicate that the effects of fMet-Leu-Phe on both phospholipid and arachidonic acid metabolism are very different from those mediated by MAF.

We have previously demonstrated that the phenolic compounds catechol, hydroquinone, and phenol increase the prostaglandin (PG) E2/leukotriene (LT) B4 ratio in human polymorphonuclear leukocytes (PMNs), while resorcinol has the opposite effect. However, in human whole blood phenols have a different effect on the thromboxane (TX) B2/LT ratio than in PMNs on the PGE2/LTB4 ratio. To establish whether the discrepancy between the results of our previous studies is due to different indicators of prostaglandin H synthase activity in PMNs (PGE2) and in whole blood (TXB2), we measured the effect of phenols on PGE2 synthesis in whole blood. The phenols only inhibited PGE2 synthesis (IC50 values for resorcinol, catechol, hydroquinone, and phenol of 10 microM, 10 microM, 60 microM and 700 microM, respectively). No significant stimulatory activity was seen as earlier in PMNs. Thus, the effect of phenols on PGE2 synthesis in whole blood is different from that in PMNs, although their order of potency to inhibit PGE2 synthesis is the same.

Incubation of [1-14C]arachidonic acid (AA) and [1-14C]prostaglandin (PG)H2 with rabbit spleen homogenate and microsomes resulted in the formation of a substance with the chromatographic properties of thromboxane (Tx)B2. The radiolabeled material was indistinguishable from authentic TxB2 on TLC in three solvent systems and on radiometric gas chromatography. The generation of TxB2-like material from AA and PGH2 was not observed after boiling of the homogenate and microsomes, and was completely inhibited by imidazole (5 mM). The transformation of AA into the TxB2-like material was not observed during incubation in the presence of indomethacin (28 microM). These results indicate that TxB2 is the principal product of arachidonic acid metabolism by the homogenate or microsomes of rabbit spleen.

In order to assess the main characteristics of the prostaglandin (PG) biosynthesis by the isolated perfused rat kidney, the urinary and venous outputs of PGE2, PGF2alpha, 6-keto-PGF1alpha and of thromboxane (Tx)B2 were followed during 120 min after an equilibration period of 30 min. Single pass kidneys were perfused with a Krebs-Henseleit solution added with Polygeline at a constant flow rate providing a perfusion pressure about 90 mm Hg. From the beginning of the study, major differences could be observed in the renal biosynthetic rate of the 4 PG studied which were mainly excreted into the venous effluent. During the perfusion, urinary and venous outputs of PGE2, PGF2alpha and of TxB2 remained stable whereas those of 6-keto-PGF1alpha sharply increased and were found inversely related to the glomerular filtration rate (r = -0.95; p n 0.001). Finally, the urinary and venous outputs of each of the four PGs studied were found positively related. It is concluded that the isolated perfused rat kidney is a valuable preparation for studying the biosynthesis of PGs and that, at least in thi model, the urinary excretion of PGs is a good index of their renal synthesis.

We investigated the vasodilating effects of verapamil, nifedipine, and nitroglycerin in relation to plasma levels of 6-keto-prostaglandin (PG)-F1 alpha, PG E1, PG F2 alpha, and thromboxane (TX) B2 in dogs. Verapamil, nifedipine, and nitroglycerin decreased peripheral vascular resistance from 1.00 +/- 0.07 mmHg/ml/min (mean +/- SE) to 0.83 +/- 0.05, from 0.99 +/- 0.06 to 0.80 +/- 0.05, and from 1.03 +/- 0.04 to 0.91 +/- 0.04, respectively. However, peripheral blood flow did not change significantly. Administration of verapamil significantly increased plasma levels of 6-keto-PG F1 alpha, PG E1, and PG F2 alpha from 150 +/- 31 pg/ml to 350 +/- 98, from 56 +/- 34 to 87 +/- 33, and from 127 +/- 35 to 238 +/- 61, respectively, while neither nifedipine nor nitroglycerin had any effect on plasma 6-keto-PG F1 alpha, PG E1, and PG F2 alpha. Indomethacin pretreatment reduced the effects of verapamil on peripheral vascular resistance and plasma PG concentration. None of these drugs caused a significant change in the plasma TX B2 level. The results suggest that the vasodilating action of verapamil was mediated in part by the prostaglandin system.

The effect of melatonin on thrombin-induced [3H]-arachidonic acid (AA) metabolism to cyclooxygenase derivatives was determined in platelets obtained from normal volunteers at 0830 and 2030 h. Percent conversion of radioactive AA was generally greater at 2030 h than at 0830 h for every cyclooxygenase derivative analyzed. Micromolar or greater concentrations of melatonin decreased significantly the conversion of [3H]-AA to prostaglandin (PG) F2 and thromboxane (Tx) B2, and inhibited slightly the conversion to PGE2 and PGD2. After preincubation of platelets with 1 mM imidazole, the melatonin inhibitory effect was significant for PGF2 only. Melatonin (10(-6) M) showed a significant inhibitory influence on platelet ATP release induced by phorbol-12 myristate-13 acetate (PMA) at 2030 h, an effect inhibited by 1 mM aspirin. These results indicate that at pharmacological concentrations melatonin inhibits human platelet cyclooxygenase.

Thromboxane B2 (TXB2), along with other primary prostaglandins, was synthesized when rat liver microsomes were incubated with radioactive arachidonic acid. TXB2 was identified directly by chemical ionization mass spectrometry and indirectly by using specific inhibitors of TX synthetase, viz., imidazole and OKY-1555 ((E)-3(4-(3-pyridyl-methyl) phenyl)-2 methyl acrylic acid HCl). The supernatant fraction obtained after centrifugation at 105,000 X g for 60 min contained a possible regulatory component that suppressed thromboxane synthesis. The regulatory influence is lost after partial hepatectomy.

Isolated, perfused and ventilated guinea-pig lungs were exposed for 10 min to acid (sulphuric + nitric acid) aerosol mimicking acid rain at pH 4.5 or 2.5, as well as to a control distilled water aerosol (pH 6.0-6.5). Lung perfusing solution was recovered and thromboxane (TX) B2 and leukotriene (LT) B4 were measured by radioimmunoassay (RIA) techniques. In a series of experiments TXB2 release averaged 0.43 +/- 0.18 (+/- SD) ng/min during exposure to distilled water aerosol and increased to 0.70 +/- 0.30 ng/min during exposure to acid aerosol at pH 4.5 (P less than 0.05). In a second series of experiments TXB2 release was 0.46 +/- 0.18 ng/min and increased to 1.07 +/- 0.51 ng/min (P less than 0.01) after acid aerosol at pH 2.5. In both cases LTB4 release, reflecting lipoxygenase activity, was unchanged. LTC4 levels were not measurable under basal conditions as well as after exposure to acid aerosol. A pneumoconstriction was also observed, being more pronounced after acid aerosol at pH 2.5. Individual sulphuric and nitric acid aerosol component solutions at pH 2.5 evoked TXB2 and airway resistance changes corresponding to those observed with the mixed acid aerosol. LTB4 was not modified. Acid rain inhalation may directly stimulate pathways leading to the bronchoconstrictor and pro-aggregating TXA2 synthesis in isolated guinea-pig lung, without affecting the lipoxygenase pathway of arachidonic acid metabolism.

We have proposed that endogenous prostacyclin opposes the vasoconstriction responsible for redistribution of regional pulmonary blood flow (rPBF) away from areas of increased regional lung water concentration (rLWC) in canine oleic acid- (OA) induced acute lung injury (D. P. Schuster and J. Haller. J. Appl. Physiol. 69: 353-361, 1990). To test this hypothesis, we related regional lung tissue concentrations of 6-ketoprostaglandin (PG) F1 alpha and thromboxane (Tx) B2 in tissue samples obtained 2.5 h after administration of OA (0.08 ml/kg iv) to rPBF and rLWC measured by positron emission tomography. After OA only (n = 16), rLWC increased in dependent lung regions. Some animals responded to increased rLWC by redistribution of rPBF away from the most edematous regions (OA-R, n = 6), whereas others did not (OA-NR, n = 10). In another six animals, meclofenamate was administered after OA (OA-meclo). After OA, tissue concentrations of 6-keto-PGF1 alpha were greater than TxB2 in all groups, but concentrations of 6-keto-PGF1 alpha were not different between OA-R and OA-NR animals. TxB2 was increased in the dependent regions of animals in both OA-R and OA-NR groups compared with controls (no OA, n = 4, P < 0.05). The tissue TxB2/6-keto-PGF1 alpha ratio was smaller in controls and OA-NR in which no perfusion redistribution occurred than in OA-R and OA-meclo in which it did occur. This TxB2/6-keto-PGF1 alpha ratio correlated significantly with the magnitude of perfusion redistribution.(ABSTRACT TRUNCATED AT 250 WORDS)

High on-aspirin platelet reactivity (HAPR) has been associated with compromised aspirin efficacy in patients with diabetes suffering from acute cardiovascular events, but the key mechanisms remain elusive. The objective of this study was to uncover the potential link between pathogenic accumulation of salicylic acid (SA), the major metabolite of aspirin, and HAPR in diabetic state. Aspirin failed to inhibit platelet CD62P expression and thromboxane (TX) B2/6-keto-prostaglandin（PG）F1α ratio in a type 2 diabetes mellitus (T2DM) mice model, particularly in the female, which were unanimously accompanied by significantly higher plasma SA concentrations. Pre-administration with SA increased both platelet CD62P expression and TXB2/6-keto-PGF1α ratio in female T2DM mice, while pretreatment with NaHCO3 caused the opposite effect. On the in vitro human umbilical vein endothelial cells (HUVECs)-platelet interaction assay, SA suppressed inflammation-induced cyclooxygenase-2 upregulation on HUVECs and attenuated their inhibitory effect on platelet aggregation in a dose-dependent manner. The prolonged retention of SA in diabetes may be partially explained by the downregulation of various SA efflux transporters in the kidney and the decreased urine pH. Importantly, in female aspirin non-responsive patients, the trough plasma concentration of SA are markedly increased with T2DM treated with long-term aspirin, and TXB2/6-keto-PGF1α ratio and uric acid level in plasma are positively correlated with SA concentration. Our findings support that the accumulation of SA represents an important factor in causing HAPR in diabetes, and that targeting impaired SA excretion may become a novel intervention strategy to diabetes-associated HAPR.

The effects of tumor necrosis factor alpha (TNF alpha) and platelet-activating factor (PAF) on monolayer permeability, cytotoxicity, and release of prostacyclin (measured as the stable metabolite 6-ketoprostaglandin [PG]F1 alpha) and thromboxane (TX)B2 were investigated in bovine pulmonary artery endothelial cells (BPAEC). After 4 h of incubation, TNF alpha (2000 U/mL) induced an increase in steady-state 125I-albumin permeability across the BPAEC monolayer (2.9 +/- 0.3%/h vs. 1.8 +/- 0.3%/h in control monolayers; n = 7, p < .05), and induced release of 6-keto-PGF1 alpha (2581 +/- 226 pg/mL vs. 863 +/- 164 pg/mL in controls; n = 16, p < .05) and TXB2 (204 +/- 14 pg/mL vs. 105 +/- 23 pg/mL in controls; n = 10, p < .05). PAF-incubation was also associated with increased 6-keto-PGF1 alpha and TXB2 release (4157 +/- 471 pg/mL and 276 +/- 32 pg/mL, respectively), but did not markedly alter morphology or increase 125I-albumin permeability. Specific tritiated deoxyglucose release and specific LDH release were unaffected by both treatments. These results indicate that TNF alpha contributed directly to increased BPAEC permeability without cytotoxicity or requirement for other serum or cellular components. However, PAF did not directly alter endothelial barrier function despite increased release of 6-keto-PGF1 alpha and TXB2.

Radioimmunoassay measurements of prostaglandins (PGs) E2, F2 alpha, 6-keto-PGF1 alpha and thromboxane (Tx) B2 in 24 h urine specimens from a male and a female healthy volunteer on several consecutive days revealed a dramatic increase of PGE2, PGF2 alpha, 6-keto-PGF1 alpha on days, upon which they had sexual intercourse; only TxB2 remained stable. Furthermore, the PGE2/PGF2 alpha ratio rose to values greater than 0.5 on days with sexual intercourse. This was found to be due to contamination of the urine samples by seminal fluid. Two 24 h urine samples from each of 26 healthy male and female volunteers (HV) revealed higher (p less than 0.01) mean PGE2 and PGF2 alpha values in males than in females. The results show that the interpretation of the urinary PG excretion as a measure of renal PG synthesis should be considered carefully, and that a PGE2/PGF2 alpha ratio greater than 0.5 indicates probable seminal contamination of urine.

Although it is well known that dietary lipids affect the course of glomerulonephritis in rats and humans, the precise mechanisms involved have not been fully elucidated. The aim of this study was to investigate the effects of different types of dietary lipids (fish oil and vegetable oil) on daunomycin (DM)-induced nephropathy in mice fed on soybean oil (SO) or cod liver oil (CLO). Urinary protein excretion, serum albumin, creatinine, total cholesterol, and TG were measured, and glomerular histological changes were evaluated. Antioxidant enzymes were also measured, along with the levels of lipid peroxide, GSH, thromboxane (Tx) B2, and 6-keto prostaglandin F1alpha in renal cortical tissue. Dietary CLO significantly reduced urinary albumin excretion and ameliorated the histological changes induced by DM. The increase of tissue lipid peroxide levels seen in SO-fed mice was suppressed in CLO-fed mice, whereas CLO-fed mice showed higher GSH levels than SO-fed mice throughout the experiment. In addition, renal tissue GSH peroxidase activity was significantly higher at 72 h after DM injection in CLO-DM mice than in SO-DM mice. Both renal cortical TxB2 and 6-keto PGF1alpha levels were significantly lower in CLO-DM mice than in SO-DM mice. These results suggest that inhibition of oxidative damage by dietary CLO played an important role in the prevention of DM nephropathy in this mouse model. The effect of CLO was closely associated with the inhibition of Tx synthesis.

In this study we investigated kinetic changes in the ratio of endothelin-1 (ET-1) and eicosanoids (6-keto-PG-F1 alpha TX-B2) in 20 x 60 mm random pattern flaps from rats. The ET-1 content of regions A (20 mm from the peripheral end) and B (20-40 mm) 6 h after surgery tended to decrease slightly compared to the ET-1 content immediately after surgery. The ET-1 content of region C (20 mm from the flap base) 6 h postoperatively increased significantly compared to that immediately after surgery. The ET-1 content of region C 6 h after surgery was significantly higher compared to that of regions A and B, which were obtained simultaneously. The ratios of eicosanoids in the three regions 6 h after surgery were significantly lower than those immediately after operation. However, the ratio in region A was higher than that in region C, showing that there was a difference in distribution in the flap between ET-1 and eicosanoids. The administration of an ETA receptor antagonist, FR-139317, extended the survival length of the flap. These results suggest that ET-1 can regulate the microcirculation in a flap directly and/or indirectly.

1. In the Lyon model, genetically hypertensive (LH) rats can be compared to both normotensive (LN) and low-blood pressure (LL) control rats. 2. Using either in vitro or in vivo approaches it was observed that LH kidneys differed from LN and LL controls by a preglomerular vasoconstriction and a decreased slope of the pressure-natriuresis curve. 3. Since young LH rats exhibited an increased urinary excretion of thromboxane (Tx) B2, the stable derivative of TxA2, the role of vasoconstrictor metabolites of arachidonic acid was investigated. Using isolated kidneys, it was demonstrated that LH kidneys did not synthesize a higher amount of TxA2 than LN or LL controls in baseline conditions but after stimulation by vasoconstrictor agents. 4. This finding suggests that such an increased ability to synthesize TxA2 may amplify the normal effect of other vasoconstrictors and thus participate in the increased renal vascular resistance observed in LH rats. 5. That hypothesis was confirmed since the blockade of the TP receptors, on which both prostaglandin H2 and TxA2 act, suppressed the preglomerular vasoconstriction seen in LH kidneys. However TP receptor blockade was devoid of effect on the pressure-natriuresis abnormalities.

1. The effects of non-steroidal anti-inflammatory drugs (NSAID) on prostacyclin and thromboxane biosynthesis and on blood pressure were determined in 46 patients with mild essential hypertension. Patients who had abstained from antihypertensive therapy for 2 weeks before study were treated with either aspirin, ibuprofen, sulindac or placebo for 7 days. 2. Excretion rates of 2,3-dinor-6-oxo-prostaglandin (PG) F1 alpha, 6-oxo-PGF1 alpha, 2,3-dinorthromboxane (TX) B2 and TXB2 were measured as indices of prostacyclin and TXA2 biosynthesis. Samples were assayed using immunoaffinity chromatography and gas chromatography/electron capture chemical ionisation mass spectrometry. 3. Aspirin and ibuprofen reduced urinary excretion of all prostacyclin- and thromboxane-derived products. Sulindac inhibited excretion of 2,3-dinor-6-oxo-PGF1 alpha, 6-oxo-PGF1 alpha and 2,3-dinor-TXB2, but had no significant effect on TXB2. 4. Systolic blood pressure increased in the ibuprofen-treated group when compared with the placebo group. There were no other significant changes in systolic or diastolic pressure in any of the treatment groups. Among the patients as a whole, there was a significant negative correlation between change in blood pressure and change in excretion of the prostacyclin-derived but not of the thromboxane-derived products. 5. We conclude that, in patients with mild essential hypertension, neither sulindac nor aspirin (in the doses used) selectively spares prostacyclin biosynthesis by the kidney. The significant relationship between increase in blood pressure and reduction in prostacyclin biosynthesis favours the possibility that in individuals who become hypertensive, prostacyclin biosynthesis determines, in part, the severity of the hypertensive state.

We have defined the metabolites of arachidonic acid (AA) secreted by alveolar macrophages (AMs) of bighorn sheep and domestic sheep in response to three agents: calcium ionophore A23187, phorbol myristate acetate (PMA), and opsonized zymosan. Cells were labeled with [3H]AA prior to stimulation and 11 tritiated metabolites, including prostaglandins (PGs), thromboxanes (TXs), leukotrienes (LTs), and hydroxyeicosatetraenoic acids (HETEs), were detected and quantitated by high-performance liquid chromotography and radiometry. Zymosan stimulation resulted in the release of significantly elevated quantities (P less than 0.05), of LTB4, [5(S), 12(R)-dihydroxy-6,14-cis-8,10-trans-eicosatetraenoic acid], 5-HETE, [5(S)-hydroxyeicosatetraenoic acid], and the nonenzymatic isomers of LTB4, [LTB I, 5(S),12(R)-6-trans-LTB4] and LTB II, [5(S), 12(S)-6-trans-LTB4], from domestic sheep AM when compared to bighorn sheep AM. Phorbol myristate acetate (PMA) stimulation released significantly elevated quantities (P less than 0.04), of TXB2, (thromboxane B2), HHT, [12(S)-12-hydroxy-5,8,10-heptadecaenoic acid], LTB I, LTB II, and 15-HETE, [15(S)-hydroxyeicosatetraenoic acid] from domestic sheep AMs when compared to bighorn sheep AMs. However, after A23187 challenge, only 15-HETE was significantly elevated (P less than 0.04) in domestic sheep AMs when compared to bighorn sheep AMs. These clear differences in AA metabolism of AMs obtained from bighorn and domestic sheep in response to three different agonists suggest not only different control mechanisms for lung metabolism of AA in the two species, but also suggest that differences in the metabolites released may lead to quite different regulation of lung defense mechanisms in the two sheep species.

The effects of infusion of the non-steroidal anti-inflammatory drugs (NSAID), tiaprofenic acid (2.2 micrograms/min or 10.0 micrograms/min) and indomethacin (1.0 microgram/min) on the release of leukotriene (LT) C4-like immunoreactivity, thromboxane (TX) B2 and 6-keto-prostaglandin (PG) F1 alpha from isolated perfused anaphylactic guinea-pig hearts were investigated. Tiaprofenic acid at both concentrations used significantly inhibited anaphylactic release of TXB2 and 6-keto-PGF1 alpha as did indomethacin (1.0 microgram/min) which was, however, about ten times more potent in this respect. Release of immunoreactive LTC4-like material was not influenced by the lower concentration of tiaprofenic acid used (2.2 micrograms/min), but significantly enhanced by the higher concentration (10.0 micrograms/min). Thus, the effect of tiaprofenic acid on eicosanoid release by the anaphylactic heart is very similar to that of indomethacin without any differential inhibition of TXB2 or 6-keto-PGF1 alpha formation.

S-(+)-2-(4-Fluorophenyl)-alpha-methyl-5-benzoxazolacetic acid (flunoxaprofen, Priaxim is a new antiinflammatory compound, which in various biological systems interferes with the generation and release of arachidonic acid metabolites of the cyclo-oxygenase pathways without affecting the formation of 5- and 12-lipoxygenase products. Flunoxaprofen reduces the concentration of thromboxane (TX)B2 (ED50 = 35.4 mg/kg p.o.) and prostaglandin (PG)E2-like activity (ED50 = 39.9 mg/kg p.o.) in the inflammatory exudate of rats 8 h after implantation of sponges soaked with carrageenan, whereas the concentration of leukotriene (LT)B4 remains in the range of that of the untreated animals (3.1 ng/ml). Flunoxaprofen inhibits cell infiltration in the exudate and this suggests that LTB4 does not initiate cell recruitment but may represent a mechanism for amplifying the inflammatory response. Using human platelets challenged with collagen, flunoxaprofen only at higher concentration (10(-4) mol/l) reduces TXB2 formation without altering generation of 12-hydroxy-5,8,10,14-eicosatetraenoic acid. This suggests a low capacity of flunoxaprofen of affecting platelet aggregation regulated by arachidonic acid metabolites. Flunoxaprofen prevents pulmonary changes due to secondary release of TXA2 in the guinea-pig. In fact this drug prevents changes due to immunological reaction and antagonizes bronchoconstriction due to exogenous administration of histamine and LTC4.(ABSTRACT TRUNCATED AT 250 WORDS)