thromboxane-b2 and nimesulide

Most available nonsteroidal anti-inflammatory drugs (NSAIDs) inhibit both the constitutive cyclooxygenase-1 (COX-1) and the inducible cyclooxygenase-2 (COX-2), resulting in inhibition of prostaglandin (PG) and thromboxane (TX) biosynthesis. The inhibition of COX-2 might be the cause of the favourable anti-inflammatory, analgesic and antipyretic effects of NSAIDs, whereas that of COX-1 might result in unwanted gastrointestinal, renal and possibly other side-effects. Nimesulide is a sulfonanilide compound with anti-inflammatory properties. Its pharmacological profile (better inhibition of PG synthesis in inflammatory areas than in gastric mucosa), suggested that it might be a selective inhibitor of COX-2. In several in vitro assays using either purified COX-2 and COX-1 preparations or cell preparations (both from animal and human origins) expressing COX-1 or COX-2, ten out of eleven different groups have demonstrated that nimesulide selectively inhibits COX-2. The COX-2/ COX-1 inhibitory ratio varies, according to the assay preparation, from about 0.76 to 0.0004 i.e. a 1.3 to 2,512-fold higher selectivity for COX-2 than for COX-1. Moreover, an in vivo whole blood assay performed on healthy volunteers demonstrated a significant fall in COX-2 PGE2 production without any effect on COX-1 TXB2 production in subjects treated with nimesulide (100 mg b.i.d. for 2 weeks) versus no effect on COX-2 PGE2 and an almost total suppression of COX-1 TXB2 in subjects treated with aspirin (300 mg t.i.d. for 2 weeks). Nimesulide can thus be considered a relatively selective COX-2 inhibitor. At the recommended dosage of 100 mg b.i.d., it is as effective an analgesic and anti-inflammatory agent as classical NSAIDs, and a well-tolerated drug with few side-effects according to large-scale open studies and a global evaluation of a large number of controlled and non-controlled comparative trials.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Cyclooxygenase 1; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Cyclooxygenase Inhibitors; Dinoprostone; Disease Models, Animal; Dose-Response Relationship, Drug; Humans; Inflammation; Isoenzymes; Membrane Proteins; Prostaglandin-Endoperoxide Synthases; Sulfonamides; Thromboxane B2

: The beneficial actions of non-steroidal anti-inflammatory drugs (NSAIDs) have been associated with inhibition of cyclooxygenase-2 (COX-2), whereas some of their adverse effects are associated mainly with inhibition of COX-1. Selective COX-2 inhibitors reduce the risk of gastrointestinal adverse events, but increase the risk of thromboembolic events pointing to importance of optimal COX-1/COX-2 inhibition in drug safety. We compared the effects of acetylsalicylic acid, ibuprofen, nabumetone and nimesulide on COX-1 and COX-2 pathways in healthy volunteers in an ex vivo set-up using single oral doses commonly used to treat acute pain. In a randomized, double-blind four-phase cross-over study, 15 healthy volunteers were given orally a single dose of either acetylsalicylic acid 500 mg, ibuprofen 400 mg, nabumetone 1 g or nimesulide 100 mg. Blood samples were drawn before and 1, 3, 6, 24 and 48 hr after the drug for the assessment of COX-1 and COX-2 activity. COX-1 activity was measured as thromboxane(2) production during blood clotting and COX-2 activity as endotoxin-induced prostaglandin E(2) synthesis in blood leucocytes. The data show that after a single oral dose these four NSAIDs have different profiles of action on COX-1 and COX-2. As expected, acetylsalicylic acid appeared to be COX-1-selective and ibuprofen effectively inhibited both COX-1 and COX-2. Nabumetone showed only a slight inhibitory effect on COX-1 and COX-2. Nimesulide caused almost complete suppression of COX-2 activity and a partial reduction of COX-1 activity. This confirms the relative COX-2 selectivity of nimesulide.

Topics: Adult; Anti-Inflammatory Agents, Non-Steroidal; Aspirin; Butanones; Cross-Over Studies; Cyclooxygenase 1; Cyclooxygenase 2; Dinoprostone; Dose-Response Relationship, Drug; Double-Blind Method; Female; Humans; Ibuprofen; Male; Nabumetone; Sulfonamides; Thromboxane B2

Selective inhibitors of cyclooxygenase (COX)-2 may provoke less gastric damage and platelet inhibition than conventional non-steroidal anti-inflammatory drugs.. We compared the biochemical and gastrointestinal effects of nimesulide, a potent and selective COX-2 inhibitor, with naproxen which exhibits no selectivity.. Thirty six healthy volunteers were randomised to nimesulide 100 mg or naproxen 500 mg twice daily for two weeks in a double blind, crossover study with a washout between treatments.. Gastrointestinal side effects were assessed by endoscopy, and by estimation of small intestinal absorption-permeability and inflammation. Comparisons were made between variables at the end of each treatment phase.. Nimesulide caused significantly less gastric injury using the modified Lanza score (p<0.001) as well as reduced duodenum injury (p=0.039). Nimesulide had lower visual analogue scores (VAS) for haemorrhage and erosive lesions in the stomach (p<0.001) and for mucosal injection in the duodenum (p=0.039). Naproxen increased excretion of calprotectin, a marker of intestinal inflammation (5.5 (1.2) to 12.1 (2.1) mg/l) while nimesulide had no effect (treatment difference p=0.03). Naproxen abolished platelet aggregation to arachidonic acid and suppressed serum thromboxane B(2) (TXB(2)) by 98%, indices of COX-1 activity. In contrast, nimesulide had no significant effect on platelet aggregation, although it reduced serum TXB(2) by 29%. Production of prostaglandin E(2) and prostacyclin by gastric biopsies, also COX-1 dependent, was inhibited by naproxen, but not by nimesulide. COX-2 activity, determined as endotoxin induced prostaglandin E(2) formation in plasma, was markedly suppressed by both treatments.. Nimesulide has preferential selectivity for COX-2 over COX-1 in vivo at full therapeutic doses and induces less gastrointestinal damage than that seen with naproxen in the short term.

Topics: Adolescent; Adult; Aged; Biomarkers; Cross-Over Studies; Cyclooxygenase Inhibitors; Double-Blind Method; Female; Gastric Mucosa; Gastrointestinal Diseases; Humans; Intestinal Mucosa; Male; Middle Aged; Naproxen; Permeability; Platelet Aggregation; Prostaglandins E; Sulfonamides; Thromboxane B2

Patients with hyperprostaglandin E syndrome/antenatal Bartter syndrome typically have renal salt wasting, hypercalciuria with nephrocalcinosis, and secondary hyperaldosteronism. Antenatally, these patients have fetal polyuria, leading to polyhydramnios and premature birth. Hyperprostaglandin E syndrome/antenatal Bartter syndrome is accompanied by a pathologically elevated synthesis of prostaglandin E(2), thought to be responsible for aggravation of clinical symptoms such as salt and water loss, vomiting, diarrhea, and failure to thrive. In this study administration of the cyclooxygenase-2 (COX-2) specific inhibitor nimesulide to patients with hyperprostaglandin E syndrome/antenatal Bartter syndrome blocked renal prostaglandin E(2) formation and relieved the key parameters hyperprostaglandinuria, secondary hyperaldosteronism, and hypercalciuria. Partial suppression of serum thromboxane B(2) synthesis resulting from platelet COX-1 activity and complete inhibition of urinary 6-keto-prostaglandin F(1alpha), reflecting endothelial COX-2 activity, indicate preferential inhibition of COX-2 by nimesulide. Amelioration of the clinical symptoms by use of nimesulide indicates that COX-2 may play an important pathogenetic role in hyperprostaglandin E syndrome/antenatal Bartter syndrome. Moreover, on the basis of our data we postulate that COX-2-derived prostaglandin E(2) is an important mediator for stimulation of the renin-angiotensin-aldosterone system in the kidney.

Topics: 6-Ketoprostaglandin F1 alpha; Adolescent; Bartter Syndrome; Blood Platelets; Child; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Cyclooxygenase Inhibitors; Dinoprostone; Humans; Indomethacin; Isoenzymes; Kidney; Membrane Proteins; Prostaglandin-Endoperoxide Synthases; Prostaglandins E; Sulfonamides; Thromboxane B2

The formation of prostacyclin (PGI(2)), thromboxane (TX) A(2), and isoprostanes is markedly enhanced in atherosclerosis. We examined the relative contribution of cyclooxygenase (COX)-1 and -2 to the generation of these eicosanoids in patients with atherosclerosis.. The study population consisted of 42 patients with atherosclerosis who were undergoing surgical revascularization. COX-2 mRNA was detected in areas of atherosclerosis but not in normal blood vessel walls, and there was evidence of COX-1 induction. The use of immunohistochemical studies localized the COX-2 to proliferating vascular smooth muscle cells and macrophages. Twenty-four patients who did not previously receive aspirin were randomized to receive either no treatment or nimesulide at 24 hours before surgery and then for 3 days. Eighteen patients who were receiving aspirin were continued on a protocol of either aspirin alone or a combination of aspirin and nimesulide. Urinary levels of 11-dehydro-TXB(2) and 2,3-dinor-6-keto-PGF(1alpha), metabolites of TXA(2) and PGI(2), respectively, were elevated in patients with atherosclerosis compared with normal subjects (3211+/-533 versus 679+/-63 pg/mg creatinine, P<0.001; 594+/-156 versus 130+/-22 pg/mg creatinine, P<0.05, respectively), as was the level of the isoprostane 8-iso-PGF(2alpha). Nimesulide reduced 2, 3-dinor-6-keto-PGF(1alpha) excretion by 46+/-5% (378.3+/-103 to 167+/-37 pg/mg creatinine, P<0.01) preoperatively and blunted the increase after surgery. Nimesulide had no significant effect on 11-dehydro-TXB(2) before (2678+/-694 to 2110+/-282 pg/mg creatinine) or after surgery. The levels of both products were lower in patients who were taking aspirin, and no further reduction was seen with the addition of nimesulide. None of the treatments influenced urinary 8-iso-PGF(2alpha) excretion.. Both COX-1 and -2 are expressed and contribute to the increase in PGI(2) in patients with atherosclerosis, whereas TXA(2) is generated by COX-1.

Topics: 6-Ketoprostaglandin F1 alpha; Adult; Aged; Anti-Inflammatory Agents, Non-Steroidal; Arteriosclerosis; Aspirin; Cyclooxygenase 1; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Cyclooxygenase Inhibitors; Dinoprost; Epoprostenol; F2-Isoprostanes; Female; Humans; Isoenzymes; Macrophages; Male; Membrane Proteins; Microscopy, Fluorescence; Muscle, Smooth, Vascular; Prostaglandin-Endoperoxide Synthases; Sulfonamides; Thromboxane A2; Thromboxane B2

Prostaglandins are generated through two isoforms of the enzyme cyclooxygenase, the constitutively expressed cyclooxygenase (Cox)-1 and Cox-2, which is induced at sites of inflammation. Selective inhibition of Cox-2 is desirable as this may avoid the gastropathy and platelet inhibition seen with nonselective agents. Moreover, these agents will allow us to examine the relative contribution of the two isoforms to prostaglandin formation in man. We examined the activity of nimesulide, a Cox-2 selective nonsteroidal antiinflammatory drug, in vitro against purified enzymes and in vivo in man. Nimesulide 100 mg twice daily or aspirin 300 mg three times daily were administered randomly for 14 days to 20 subjects complaining of musculoskeletal pain. Serum thromboxane B2 was determined as an index of Cox-1 activity and endotoxin-induced prostaglandin E2 formation in whole blood as an index of Cox-2 activity. Urinary excretion of prostaglandin metabolites was determined by GC/MS. Nimesulide was highly selective against ovine Cox-2, so that at concentrations attained in vivo, it had no effect on Cox-1 but completely suppressed Cox-2. Aspirin markedly inhibited serum thromboxane B2 (181.92 +/- 19.77 to 2.83 +/- 0.96 ng/ml, P <. 002), whereas nimesulide had very little effect (207.53 +/- 47.30 to 181.15 +/- 54.59 ng/ml). In contrast, nimesulide suppresses endotoxin-induced prostaglandin E2 formation (35.03 +/- 8.73 to 2.62 +/- 0.95 ng/ml, P =.002). As expected, aspirin reduced TX metabolite excretion, whereas nimesulide had no significant effect. In contrast, both compounds suppressed PGI2 formation to the same extent. The findings suggest that TX is largely Cox-1 derived. Moreover, Cox-2 is expressed in man and generates prostaglandin I2.

Topics: Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Cyclooxygenase Inhibitors; Female; Humans; Isoenzymes; Male; Membrane Proteins; Middle Aged; Platelet Aggregation; Prostaglandin-Endoperoxide Synthases; Prostaglandins; Sulfonamides; Thromboxane B2

On the basis of molecular modelling studies, five new compounds were synthesised and studied in an attempt to design new lead structures as selective COX-2 inhibitors.

Topics: Cell Survival; Crystallography, X-Ray; Cyclooxygenase 1; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Cyclooxygenase Inhibitors; Drug Design; Humans; In Vitro Techniques; Indicators and Reagents; Isoenzymes; Membrane Proteins; Models, Molecular; Molecular Conformation; Monocytes; Prostaglandin-Endoperoxide Synthases; Quantitative Structure-Activity Relationship; Sulfonamides; Thromboxane B2

1. Cyclo-oxygenase (COX) and lipoxygenase (LO) share a common substrate, arachidonic acid. Aspirin and related drugs inhibit COX activity. In a subset of patients with asthma aspirin induces clinical symptoms associated with increased levels of certain LO products, a phenomenon known as aspirin-sensitive asthma. The pharmacological pathways regulating such responses are not known. 2. Here COX-1 and LO activity were measured respectively by the formation of thromboxane B(2) (TXB(2)) or leukotrienes (LT) C(4), D(4) and E(4) in whole blood stimulated with A23187. COX-2 activity was measured by the formation of prostaglandin E(2) (PGE(2)) in blood stimulated with lipopolysaccharide (LPS) for 18 h. 3. No differences in the levels of COX-1, COX-2 or LO products or the potency of drugs were found in blood from aspirin sensitive vs aspirin tolerant patients. Aspirin, indomethacin and nimesulide inhibited COX-1 activity, without altering LO activity. Indomethacin, nimesulide and the COX-2 selective inhibitor DFP [5,5-dimethyl-3-(2-isopropoxy)-4-(4-methanesulfonylphenyl)-2(5H)-furanone] inhibited COX-2 activity. NO-aspirin, like aspirin inhibited COX-1 activity in blood from both groups. However, NO-aspirin also reduced LO activity in the blood from both patient groups. Sodium salicylate was an ineffective inhibitor of COX-1, COX-2 or LO activity in blood from both aspirin-sensitive and tolerant patients. 4. Thus, when COX activity in the blood of aspirin-sensitive asthmatics is blocked there is no associated increase in LO products. Moreover, NO-aspirin, unlike other NSAIDs tested, inhibited LO activity in the blood from both aspirin sensitive and aspirin tolerant individuals. This suggests that NO-aspirin may be better tolerated than aspirin by aspirin-sensitive asthmatics.

Topics: Anti-Inflammatory Agents, Non-Steroidal; Aspirin; Asthma; Benzene Derivatives; Calcimycin; Cyclooxygenase 1; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Cyclooxygenase Inhibitors; Dinoprostone; Dose-Response Relationship, Drug; Furans; Humans; Indomethacin; Ionophores; Isoenzymes; Leukotrienes; Lipopolysaccharides; Lipoxygenase; Membrane Proteins; Prostaglandin-Endoperoxide Synthases; Sulfonamides; Thromboxane B2

The cyclooxygenase (COX) product, prostacyclin (PGI(2)), inhibits platelet activation and vascular smooth-muscle cell migration and proliferation. Biochemically selective inhibition of COX-2 reduces PGI(2) biosynthesis substantially in humans. Because deletion of the PGI(2) receptor accelerates atherogenesis in the fat-fed low density lipoprotein receptor knockout mouse, we wished to determine whether selective inhibition of COX-2 would accelerate atherogenesis in this model. To address this hypothesis, we used dosing with nimesulide, which inhibited COX-2 ex vivo, depressed urinary 2,3 dinor 6-keto PGF(1alpha) by approximately 60% but had no effect on thromboxane formation by platelets, which only express COX-1. By contrast, the isoform nonspecific inhibitor, indomethacin, suppressed platelet function and thromboxane formation ex vivo and in vivo, coincident with effects on PGI(2) biosynthesis indistinguishable from nimesulide. Indomethacin reduced the extent of atherosclerosis by 55 +/- 4%, whereas nimesulide failed to increase the rate of atherogenesis. Despite their divergent effects on atherogenesis, both drugs depressed two indices of systemic inflammation, soluble intracellular adhesion molecule-1, and monocyte chemoattractant protein-1 to a similar but incomplete degree. Neither drug altered serum lipids and the marked increase in vascular expression of COX-2 during atherogenesis. Accelerated progression of atherosclerosis is unlikely during chronic intake of specific COX-2 inhibitors. Furthermore, evidence that COX-1-derived prostanoids contribute to atherogenesis suggests that controlled evaluation of the effects of nonsteroidal anti-inflammatory drugs and/or aspirin on plaque progression in humans is timely.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Coronary Artery Disease; Cyclooxygenase 1; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Cyclooxygenase Inhibitors; Epoprostenol; Female; Indomethacin; Isoenzymes; Male; Membrane Proteins; Mice; Mice, Inbred C57BL; Mice, Knockout; Prostaglandin-Endoperoxide Synthases; Receptors, LDL; Sulfonamides; Thromboxane B2

F(2)-isoprostanes are bioactive peroxidation products of arachidonic acid whose urinary excretion provides an index of lipid peroxidation in vivo. We tested the hypothesis that formation of F(2)-isoprostanes is altered in patients with cystic fibrosis and contributes to platelet activation and pulmonary dysfunction in this setting. The urinary excretion of immunoreactive 8-iso-prostaglandin F(2alpha) (PGF(2alpha)) was significantly (p = 0.0001) higher in 36 patients with cystic fibrosis than in 36 age-matched healthy subjects: 618 +/- 406 versus 168 +/- 48 pg/mg creatinine. The urinary excretion of immunoreactive 11-dehydro-thromboxane B(2) (TXB(2)), an index of in vivo platelet activation, was also significantly (p = 0.0001) higher in patients than in control subjects: 2,440 +/- 1,453 versus 325 +/- 184 pg/mg creatinine. The excretion rate of 8-iso-PGF(2alpha) was correlated with that of 11-dehydro-TXB(2) (rho = 0.51; p = 0.0026) and inversely related to FEV(1) (rho = -0.40; p = 0.0195). Urinary 8-iso-PGF(2alpha) excretion was largely unaffected during cyclooxygenase inhibition with low-dose aspirin, nimesulide, or ibuprofen, consistent with a noncyclooxygenase mechanism of F(2)-isoprostane formation in cystic fibrosis. Increased vitamin E supplementation (from 200 to 600 mg/d) was associated with statistically significant (p = 0.005) reductions in urinary 8-iso-PGF(2alpha) and 11-dehydro-TXB(2) excretion, by 42% and 29%, respectively. We conclude that enhanced lipid peroxidation is an important feature of cystic fibrosis and may contribute to persistent platelet activation and pulmonary dysfunction via generation of bioactive isoeicosanoids. Our results provide a rationale for reassessing the adequacy of vitamin E supplementation in this setting.

Topics: Adolescent; Adult; Child; Cyclooxygenase Inhibitors; Cystic Fibrosis; Dinoprost; F2-Isoprostanes; Female; Genotype; Humans; Ibuprofen; Lipid Peroxidation; Lung; Male; Platelet Activation; Sulfonamides; Thromboxane B2; Vitamin E

The analgesic drug tramadol has been shown to relieve pain in inflammatory conditions, to inhibit the development of experimental inflammation, and to reduce prostaglandin (PG)E(2)concentrations in the inflammatory exudate. In this study, we evaluated the putative activity of tramadol to suppress prostaglandin endoperoxide synthase-1 (PGHS-1), and prostaglandin endoperoxide synthase-2 (PGHS-2) activities in human whole blood in vitro. Platelet thromboxane (Tx)B(2)production and monocyte PGE(2)production in LPS- stimulated blood were measured in samples incubated with different concentrations (300 ng/ml, 3 microg/ml, 30 microg/ml) of tramadol or its enantiomers. Neither tramadol nor the enantiomers inhibited the formation of arachidonic acid metabolites. Our results indicate that the anti-inflammatory effect of tramadol demonstrated in some models is not related to a direct inhibitory effect on the formation of prostanoids.

Topics: Analgesics, Opioid; Anti-Inflammatory Agents; Aspirin; Blood Platelets; Cyclooxygenase 1; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Cyclooxygenase Inhibitors; Dinoprostone; Humans; In Vitro Techniques; Isoenzymes; Membrane Proteins; Monocytes; Prostaglandin-Endoperoxide Synthases; Sulfonamides; Thromboxane B2; Tramadol

1. In this study we describe experiments to establish ex vivo the selectivity of non-steroidal anti-inflammatory drugs (NSAIDs) given in vivo. 2. Anaesthetised (Inactin, 120 mg kg(-1)) male Wistar rats (220-250 g) received an i.v. dose of one of the following compounds (dose mg kg(-1)): aspirin (20), diclofenac (3), L-745,337 (30), nimesulide (15), salicylate (20), sulindac (10). Blood samples were taken before and up to 6 h after dosing and the plasma obtained from it was tested for its ability to inhibit prostanoid formation in IL-1beta-treated A549 cells (COX-2 system) and human washed platelets (COX-1 system). For control the same compounds were also added directly to the assay systems. 3. All drugs, except sodium salicylate, inhibited COX-1 and COX-2 when added directly to the test systems. Plasma from aspirin-treated rats was without effect on either COX-1 or COX-2, consistent with the rapid in vivo metabolism to salicylate. Conversely, plasma from sulindac-treated rats inhibited COX-1 and COX-2 with potencies according with in vivo metabolism to sulindac sulphide. Diclofenac was COX-1/2 non-selective when tested in vitro, but a slightly preferential inhibitor of COX-2 when tested ex vivo. Nimesulide was confirmed as preferential inhibitor of COX-2 both in vitro and ex vivo. L-745,337 was a selective COX-2 inhibitor when tested in vitro or ex vivo. 4. In conclusion, our experiments show clearly (a) NSAIDs inactivation, (b) activation of prodrugs, and (c) NSAIDs selectivity. Our assay provides useful information about the selectivity of NSAIDs that could be extended by the analysis of plasma samples taken from humans similarly treated with test drugs.

Topics: Analgesics; Animals; Anti-Inflammatory Agents, Non-Steroidal; Aspirin; Blood Platelets; Blood Pressure; Carcinoma; Cyclooxygenase 1; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Cyclooxygenase Inhibitors; Diclofenac; Dinoprostone; Humans; Indans; Isoenzymes; Male; Membrane Proteins; Prostaglandin-Endoperoxide Synthases; Rats; Rats, Wistar; Salicylates; Substrate Specificity; Sulfonamides; Sulindac; Thromboxane B2; Tumor Cells, Cultured

Novel aspirin (ASA)-triggered 15-epi-lipoxins (ATL) comprise new potent bioactive eicosanoids that may contribute to the therapeutic effect of this drug. ATL biosynthesis is initiated by ASA acetylation of cyclooxygenase (COX)-2 and was originally identified during the interaction of leukocytes with either endothelial or epithelial cells. Here, we examined ATL biosynthesis in rat hepatocytes either alone or in coincubation with nonparenchymal liver cells (NPC) and in liver homogenates from ASA-treated rats. Rat hepatocytes and CC-1 cells, a rat hepatocyte cell line, displayed COX-1 but not COX-2 mRNA expression and predominantly produced thromboxane A(2) (TXA(2)) and 15-hydroxyeicosatetraenoic acid (15-HETE). In these cells, ASA shifted the arachidonic acid metabolism from TXA(2) to 15-HETE in a concentration-dependent manner. In contrast, neither indomethacin, ibuprofen, valeryl salicylate, nor nimesulide was able to trigger 15-HETE biosynthesis. SKF-525A, a cytochrome P-450 inhibitor, significantly reduced the effect of ASA on 15-HETE biosynthesis. Furthermore, phenobarbital, a potent inducer of cytochrome P-450 activity, further increased ASA-induced 15-HETE production. ASA treatment of hepatocyte-NPC coincubations resulted in the generation of significant amounts of ATL. In addition, in vivo experiments demonstrated augmented hepatic levels of 15-epi-lipoxin A(4) in ASA-treated rats. Taken together and considering that ASA is hydrolyzed on its first pass through the portal circulation, these data indicate that, during ASA's consumption, liver tissue generates biologically relevant amounts of ATL by COX-2-independent mechanisms.

Topics: Animals; Aspirin; Cells, Cultured; Cyclooxygenase 1; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Cyclooxygenase Inhibitors; Cytochrome P-450 Enzyme System; Dose-Response Relationship, Drug; Enzyme Activation; Excitatory Amino Acid Antagonists; Gene Expression Regulation, Enzymologic; Hydroxyeicosatetraenoic Acids; Ibuprofen; Indomethacin; Isoenzymes; Lipoxins; Liver; Male; Membrane Proteins; Phenobarbital; Prostaglandin-Endoperoxide Synthases; Rats; Rats, Wistar; RNA, Messenger; Sulfonamides; Thromboxane B2

The present study examined the inhibitory profiles of NS-398 and nimesulide against prostaglandin (PG) formation in inflammatory and non-inflammatory sites, and compared them with those of aspirin and indomethacin. In vitro, indomethacin inhibited PGH synthase (PGHS)-1 and PGHS-2 almost equally, while NS-398 and nimesulide inhibited only PGHS-2. NS-398 (1, 10 mg/kg) and nimesulide (3 mg/kg) slowed the rate of plasma exudation and thus the exudate accumulation in rat carrageenin-induced pleurisy. Aspirin (30, 100 mg/kg) and indomethacin (10 mg/kg) also reduced this rate. NS-398 and nimesulide reduced the PGE2 more potently than TXB2 and 6-keto-PGF1 alpha in the exudate. However, aspirin and indomethacin did not exhibit this selectivity. The levels of PGE2 correlated significantly with the plasma exudation rate. Moreover, nimesulide (3 mg/kg) did not affect PGE2 formation in rat stomachs injected with 1 M NaCl solution, while indomethacin (10 mg/kg) reduced it. Thus, NS-398 and nimesulide exhibit different inhibitory profiles from aspirin and indomethacin against PG formation. These results suggest that PGE2 may be produced by PGHS-2 in the inflammatory site, and may play a more prominent role than PGI2 in plasma exudation.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Anti-Inflammatory Agents, Non-Steroidal; Aspirin; Cyclooxygenase 1; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Cyclooxygenase Inhibitors; Dinoprostone; Dose-Response Relationship, Drug; Gastric Juice; Indomethacin; Isoenzymes; Male; Membrane Proteins; Nitrobenzenes; Pleurisy; Prostaglandin-Endoperoxide Synthases; Prostaglandins; Rats; Rats, Sprague-Dawley; Sodium Chloride; Sulfonamides; Thromboxane B2

Rat carrageenin-induced pleurisy was used to clarify the role of prostaglandin H synthase (PGHS)-2 in acute inflammation. Intrapleural injection of 0.2 ml of 2% lambda-carrageenin induced accumulation of exudate and infiltration of leukocytes into the pleural cavity. When PGHS-1 and -2 proteins in the pleural exudate cells were analyzed by Western blot analysis, PGHS-2 was detectable from 1 hr after carrageenin injection. Its level rose sharply, remained high from 3 to 7 hr after injection, and then fell to near the detection limit. PGHS-1 was also detected, but kept almost the same level throughout the course of the pleurisy. Levels of prostaglandin (PG) E2 and thromboxane (TX) B2 in the exudate increased from hour 3 to hour 7, and then declined. Thus, the changes of the level of PGE2 were closely paralleled those of PGHS-2. The selective PGHS-2 inhibitors NS-398, nimesulide and SC-58125 suppressed the inflammatory reaction and caused a marked decrease in the level of PGE2 but not in those of TXB2 and 6-keto-PGF 1 alpha. These results suggest that the PGHS-2 expressed in the pleural exudate cells may be involved in PGE2 formation at the site of inflammation.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Anti-Inflammatory Agents; Azo Compounds; Blotting, Western; Carrageenan; Cell Count; Cells, Cultured; Coloring Agents; Cyclooxygenase Inhibitors; Dexamethasone; Dinoprostone; Excipients; Inflammation; Isoenzymes; Leukocytes; Male; Nitrobenzenes; Pleura; Prostaglandin-Endoperoxide Synthases; Pyrazoles; Rats; Rats, Sprague-Dawley; Sulfonamides; Thromboxane B2; Trypan Blue