ozagrel and Disease-Models--Animal

In light of recent findings showing that platelets play important roles in the development of endometriosis in general and in fibrogenesis in particular, this study investigated the efficacy of Ozagrel, a TXA

Topics: Animals; Blood Platelets; Cell Proliferation; Disease Models, Animal; Endometriosis; Female; Hyperalgesia; Macrophages; Methacrylates; Mice; Neovascularization, Pathologic; Platelet Aggregation Inhibitors; Treatment Outcome

We investigated the neuroprotective properties of single doses of minocycline and ozagrel when administered prior to stroke. Male Sprague-Dawley rats were assigned randomly to one of the following groups: (1) control (Con) group (n=10), (2) minocycline (Mino) group (n=10), (3) sodium ozagrel (SO) group (n=10). Rats were treated with a single dose of minocycline or ozagrel at 30min before stroke. A middle cerebral artery occlusion (MCAO) was made at 30min after drug administration and reperfusion was done. The rats were subjected to a neurobehavioral test at days 1, 3 and 7 after MCAO. The cerebral ischemic volume was quantified by MetaMorph imaging software after TTC staining. The neuronal cell survival and astrocytes expansion were assessed by the NeuN and GFAP immunohistofluorescence staining. Apoptosis was detected by the TUNEL assay. We statistically analyzed and compared the results with each other. Mino and SO groups had neuroprotective effect and showed a better behavioral performance of adhesive removal and treadmill test at 7 days after stroke. Mino and SO groups also showed a smaller infarct volume than control group at 7 days after stroke. Immunohistofluorescence staining showed a higher number of NeuN positive cells, lower activated astrocytes in GFAP and a lower apoptosis in TUNEL staining. This study showed that single doses of minocycline and ozagrel prior to stroke had neuroprotective effects. These agents will be useful not only in post-stroke therapy but also in stroke prevention in several cerebrovascular procedures like carotid endarterectomy, bypass procedure, endovascular angioplasty, thromboembolectomy or thrombolysis.

Topics: Animals; Apoptosis; Astrocytes; Brain; Cell Survival; Disease Models, Animal; Fibrinolytic Agents; Infarction, Middle Cerebral Artery; Ischemic Attack, Transient; Male; Methacrylates; Minocycline; Neurons; Neuroprotective Agents; Neuropsychological Tests; Random Allocation; Rats, Sprague-Dawley; Stroke; Treatment Outcome

Overdosed acetaminophen (paracetamol, N-acetyl-p-aminophenol; APAP) causes severe liver injury. We examined the effects of ozagrel, a selective thromboxane A2 (TXA2) synthase inhibitor, on liver injury induced by APAP overdose in mice.. Hepatotoxicity was induced to ICR male mice by an intraperitoneal injection with APAP (330 mg/kg). The effects of ozagrel (200 mg/kg) treatment 30 min after the APAP injection were evaluated with mortality, serum alanine aminotransferase (ALT) levels and hepatic changes, including histopathology, DNA fragmentation, mRNA expression and total glutathione contents. The impact of ozagrel (0.001-1 mg/mL) on cytochrome P450 2E1 (CYP2E1) activity in mouse hepatic microsome was examined. RLC-16 cells, a rat hepatocytes cell line, were exposed to 0.25 mM N-acetyl-p-benzoquinone imine (NAPQI), a hepatotoxic metabolite of APAP. In this model, the cytoprotective effects of ozagrel (1-100 muM) were evaluated by the WST-1 cell viability assay.. Ozagel treatment significantly attenuated higher mortality, elevated serum alanine aminotransferase levels, excessive hepatic centrilobular necrosis, hemorrhaging and DNA fragmentation, as well as increase in plasma 2,3-dinor thromboxane B2 levels induced by APAP injection. Ozagrel also inhibited the hepatic expression of cell death-related mRNAs induced by APAP, such as jun oncogene, FBJ osteosarcoma oncogene (fos) and C/EBP homologous protein (chop), but did not suppress B-cell lymphoma 2-like protein11 (bim) expression and hepatic total glutathione depletion. These results show ozagrel can inhibit not all hepatic changes but can reduce the hepatic necrosis. Ozagrel had little impact on CYP2E1 activity involving the NAPQI production. In addition, ozagrel significantly attenuated cell injury induced by NAPQI in RLC-16.. We demonstrate that the TXA2 synthase inhibitor, ozagrel, dramatically alleviates liver injury induced by APAP in mice, and suggest that it is a promising therapeutic candidate for the treatment of APAP-induced liver injury.

Topics: Acetaminophen; Alanine Transaminase; Animals; Chemical and Drug Induced Liver Injury; Disease Models, Animal; DNA Fragmentation; Dose-Response Relationship, Drug; Glutathione; Injections, Intraperitoneal; Liver; Male; Methacrylates; Mice; Mice, Inbred ICR; Thromboxane-A Synthase; Treatment Outcome

ONO-1301 is a novel drug that acts as a prostacyclin agonist with thromboxane A(2) (TxA(2)) synthase inhibitory activity. We investigated the effect of ONO-1301 on development of airway allergic inflammation.. Mice sensitized and challenged to ovalbumin (OVA) received ONO-1301, OKY-046 (TxA(2) synthase inhibitor), beraprost, a prostacyclin receptor (IP) agonist, ONO-1301 plus CAY10449 (selective IP antagonist) or vehicle during the challenge period. Twenty-four hours after the OVA challenge, airway hyperresponsiveness (AHR) to methacholine was assessed and bronchoalveolar lavage was performed. Lung specimens were excised for goblet cell staining and analysis of lung dendritic cells (DCs). Bone marrow-derived dendritic cells (BMDCs) were generated, in the presence or absence of drugs, for analysis of DC function.. Mice that received ONO-1301 showed significantly lower AHR, airway eosinophilia, T-helper type 2 cytokine levels, mucus production and lung DCs numbers than vehicle-treated mice. These effects of ONO-1301 were mostly reversed by CAY10449. BMDCs treated with ONO-1301 alone showed lower DC functions, such as expression of costimulatory factors or stimulation to spleen T cells.. These data suggest that ONO-1301 may suppress AHR and airway allergic inflammation through modulation of DCs, mainly mediated through the IP receptor. This agent may be effective as an anti-inflammatory drug in the treatment of asthma.

Topics: Animals; Bronchial Hyperreactivity; Dendritic Cells; Disease Models, Animal; Epoprostenol; Female; Inflammation; Methacrylates; Mice; Mice, Inbred BALB C; Ovalbumin; Pyridines; Thromboxane-A Synthase; Thromboxanes

Sodium ozagrel (SO) prevents platelet aggregation and vasoconstriction in the cerebral ischemia. It plays an important role in the prevention of brain damage induced by cerebral ischemia/reperfusion. Recently, many animal studies have suggested that the Panax ginseng (PG) has neuroprotective effects in the ischemic brain. In this study, we assessed the neuroprotective effects that come from a combination therapy of SO and PG in rat models with middle cerebral artery occlusion (MCAO). Animals with MCAO were assigned randomly to one of the following four groups: (1) control (Con) group, (2) SO group (3 mg/kg, intravenously), (3) PG group (200 mg/kg, oral feeding), and (4) SO + PG group. The rats were subjected to a neurobehavior test including adhesive removal test and rotarod test at 1, 3, 7, 10, and 15 days after MCAO. The cerebral ischemic volume was quantified by Metamorph imaging software after 2-3-5-triphenyltetrazolium (TTC) staining. The neuronal cell survival and astrocytes expansion were assessed by immunohistofluorescence staining. In the adhesive removal test, the rats of PG or SO + PG group showed significantly better performance than those of the control group (Con: 88.1 ± 24.8, PG: 43.6 ± 11, SO + PG: 11.8 ± 7, P < .05). Notably, the combination therapy group (SO + PG) showed better performance than the SO group alone (SO: 56 ± 12, SO + PG: 11.8 ± 7, P < .05). In TTC staining for infarct volume, cerebral ischemic areas were also significantly reduced in the PG group and SO + PG group (Con: 219 ± 32, PG: 117 ± 8, SO + PG: 99 ± 11, P < .05). Immunohistofluorescence staining results showed that the group which received SO + PG group therapy had neuron cells in the normal range. They also had a low number of astrocytes and apoptotic cells compared with the control or SO group in the peri-infarction area. During astrocytes staining, compared to the SO + PG group, the PG group showed only minor differences in the number of NeuN-positive cells and quantitative analysis of infarct volume. In conclusion, these studies showed that in MCAO rat models, the combination therapy with SO and PG may provide better neuroprotective effects such as higher neuronal cell survival and inhibition of astrocytes expansion than monotherapy with SO alone.

Topics: Animals; Antigens, Nuclear; Apoptosis; Astrocytes; Behavior, Animal; Disease Models, Animal; Drug Synergism; Drug Therapy, Combination; Drugs, Chinese Herbal; Fibrinolytic Agents; Infarction, Middle Cerebral Artery; Ischemic Attack, Transient; Methacrylates; Nerve Tissue Proteins; Neurons; Neuroprotective Agents; Panax; Rats

In acute pancreatitis, pancreatic phospholipase A(2) (PLA2) in the circulating blood hydrolyzes phospholipids contained in plasma lipoproteins, liberating eicosanoid precursors that are subsequently converted to various eicosanoids. The pathophysiological significance of eicosanoid synthesis via this pathway is unknown. The aim of this study was to clarify the role of thromboxane A(2) (TXA(2)) synthesis by circulating pancreatic PLA(2) in the pathogenesis of the systemic complications of acute pancreatitis.. Guinea pigs were divided into two groups: a control group and an ozagrel group, which received intravenous administration of ozagrel, a selective TXA(2) synthetase inhibitor. Pancreatic PLA(2) was infused intravenously in both groups for 30 min, and systemic changes during the infusion were examined.. In the control group, there was an increase in plasma thromboxane B(2) (TXB(2)) concentration, a decrease in mean arterial pressure and heart rate, a decrease in arterial base excess (BE), bicarbonate concentration (HCO(3) (-)), and pH, a decrease in platelet count and plasma fibrinogen concentration, and a shortened prothrombin time during the infusion of pancreatic PLA(2). In the ozagrel-treated group, changes in plasma TXB(2) concentration, BE, HCO(3) (-), and platelet count were significantly inhibited.. TXA(2) synthesis by circulating pancreatic PLA(2) contributes to metabolic acidosis and thrombocytopenia during acute pancreatitis.

Topics: Acute Disease; Animals; Blood Pressure; Disease Models, Animal; Enzyme Inhibitors; Guinea Pigs; Heart Rate; Injections, Intravenous; Male; Methacrylates; Pancreatitis; Phospholipases A; Phospholipases A2; Thromboxane-A Synthase; Treatment Outcome

Platelet activation and subsequent aggregation play a key role in the pathogenesis of ischemic brain damage. Recent studies revealed that enhanced platelet activation is also observed after ischemia, suggesting that secondary thrombus formation might participate in the development of cerebral infarction. The binding of platelet glycoprotein GPIIb/IIIa (integrin alpha(IIb)beta3) to fibrinogen is the final common pathway in platelet aggregation. Therefore, GPIIb/IIIa antagonists might be useful in acute ischemic stroke as well as in the secondary prevention of ischemic stroke. In the present study, we evaluated the effect of three compounds, FK419 ((S)-2-acetylamino-3-[(R)-[1-[3-(piperidin-4-yl) propionyl] piperidin-3-ylcarbonyl] amino] propionic acid trihydrate), a novel nonpeptide GPIIb/IIIa antagonist, ozagrel, a selective thromboxane A(2) synthase inhibitor, and argatroban, a thrombin inhibitor, on middle cerebral artery (MCA) patency and ischemic brain damage using photochemically induced MCA thrombosis model in guinea pigs. FK419, ozagrel, or argatroban was administered 5 min after the termination of photoirradiation. FK419 dose-dependently improved MCA patency by decreasing the total occlusion time, time to continuous reperfusion, and the number of cyclic flow reductions, at doses that inhibited ADP-induced platelet aggregation ex vivo. In contrast, ozagrel only improved total occlusion time, and argatroban showed no improvement in MCA patency. FK419 also reduced ischemic brain damage in a dose-dependent fashion, whereas ozagrel and argatroban did not. Finally, FK419 ameliorated neurological deficits, whereas ozagrel and argatroban did not. These results indicate that FK419, a GPIIb/IIIa antagonist, ameliorates ischemic brain damage by improving MCA patency after occlusion and that FK419 is a promising candidate for the treatment of acute ischemic stroke.

Topics: Animals; Antithrombins; Arginine; Blood Coagulation; Blood Platelets; Brain Ischemia; Disease Models, Animal; Guinea Pigs; Infarction, Middle Cerebral Artery; Male; Methacrylates; Pipecolic Acids; Platelet Aggregation Inhibitors; Platelet Glycoprotein GPIIb-IIIa Complex; Reperfusion Injury; Sulfonamides; Thromboxane B2

The therapeutic efficacy of ozagrel sodium (ozagrel), alone and in combination with heparin, and its therapeutic time window were studied in a photochemically induced thrombotic cerebral infarction rat model. Cerebral artery thrombosis was induced by irradiating the brain with green light through intact skull using rose bengal as the photosensitizing dye. One set of animals was treated immediately after thrombosis with (1) vehicle, (2) 10 mg/kg ozagrel in saline, intravenously (i.v.), (3) 150 U/kg unfractioned heparin, subcutaneously (s.c.), or (4) ozagrel, i.v. plus heparin, s.c. Infarct volume was significantly smaller and edema was reduced in the ozagrel-treated groups compared to the vehicle-treated group; heparin did not convey additional benefit. In another set of animals, rats were given either vehicle or 10 mg/kg ozagrel in saline, i.v., 60 min or 120 min after induction of thrombosis. Ozagrel reduced infarct volume, but its effect diminished with delayed administration. The therapeutic window was determined to be less than 60 minutes after induction of thrombosis.

Topics: Animals; Cerebral Arteries; Cerebral Infarction; Disease Models, Animal; Drug Therapy, Combination; Fibrinolytic Agents; Heparin; Image Processing, Computer-Assisted; Injections, Intravenous; Injections, Subcutaneous; Intracranial Thrombosis; Light; Male; Methacrylates; Rats; Rats, Sprague-Dawley; Thromboxane-A Synthase; Time Factors; Treatment Outcome

Biologically active substances, such as prostaglandins, thromboxanes, and leukotrienes, which are metabolites involved in the arachidonic acid cascade, are detected in herniated disc samples obtained from patients with lumbar disc herniation. However, little is known concerning the relationships between these substances and clinical symptoms such as radicular pain. Thromboxane A2 (TXA2) induces not only potent platelet aggregation, but also blood vessel contraction. Leukotriene B4 (LTB4), a potent chemotactic agent, plays a role in inflammatory reactions by recruiting neutrophils and lymphocytes. The purpose of this study was to examine the roles of TXA2 and LTB4 in the hyperalgesia induced by application of nucleus pulposus to the lumbar nerve root in the rat. TXA2 synthetase inhibitor and LTB4 receptor antagonist, which were injected into the epidural space, decreased mechanical hyperalgesia at both three and seven days after epidural injection. There were no significant differences in sensitivity to noxious thermal stimuli following application of the nucleus pulposus or an epidural injection. Epidural injection of LTB4 receptor antagonist and/or TXA2 synthetase inhibitor may attenuate the painful radiculopathy due to lumbar disc herniation. In conclusion, our findings suggest that TXA2 and LTB4 may play significant roles in mechanical hyperalgesia induced by autologous nucleus pulposus.

Topics: Animals; Disease Models, Animal; Enzyme Inhibitors; Hyperalgesia; Intervertebral Disc Displacement; Leukotriene B4; Male; Methacrylates; Motor Activity; Phenylpropionates; Rats; Rats, Sprague-Dawley; Receptors, Leukotriene B4; Shoulder Pain; Thromboxane A2; Thromboxane-A Synthase

1. The purpose of this study was to investigate the involvement of thromboxane A(2) (TXA(2)) in the cough response in a guinea-pig cough model. Here, we describe results obtained using a selective TXA(2) synthetase inhibitor, ozagrel, and a selective TXA(2) agonist, U-46619. 2. Guinea-pigs were anaesthetized and exposed to an aerosol of capsaicin (100 microM) to elicit coughing. The number of coughs was 20.0+/-5.8 during capsaicin provocation (5 min), but only 2. 8+/-0.4 during a 5-min inhalation of phosphate-buffered saline (PBS) (P:<0.05). 3. TXB(2) levels in BAL were 101.4+/-8.0 and 58.4+/-8.7 pg ml(-1) following capsaicin and PBS inhalation, respectively (P:<0. 01), but there was no intergroup difference in the cell populations in BAL. 4. Inhalation of U-46619 did not induce a cough response by itself at concentrations of 100 ng ml(-1) to 10 microg ml(-1). However, it caused a 2 fold increase in the number of capsaicin-induced coughs. 5. To explore the source of the TXA(2), BAL cells were stimulated with capsaicin and the supernatants collected for analysis. The TXB(2) concentration in BAL was increased dose-dependently, indicating that TXA(2) is released from BAL cells in response to capsaicin. 6. Ozagrel was administered orally 1 h before a 5 min capsaicin provocation and the number of coughs was counted during the capsaicin inhalation. Ozagrel decreased the number of coughs dose-dependently (ED(50) value, 26.3 mg kg(-1)). 7. These results show that TXA(2) modulates the capsaicin-induced cough response by increasing capsaicin-sensitivity.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Antitussive Agents; Capsaicin; Cough; Disease Models, Animal; Dose-Response Relationship, Drug; Guinea Pigs; Male; Methacrylates; Thromboxane A2; Thromboxane-A Synthase

To elucidate the role of thromboxane A2 (TxA2) and prostaglandin I2 (PGI2) in acute necrotizing pancreatitis (ANP) in rats and to determine the effect of the TxA2 synthesis inhibitor OKY-046 and the PGI2 analogue OP-2507, the levels of two prostanoids (TxB2, 6-keto PGF1alpha) and two types of phospholipase A2 (PLA2) activity (cytosolic and secretory) were measured in plasma and three tissues (pancreas, lung, and kidney) after injection of a mixed solution of 5% sodium taurocholate and 0.1% trypsin into the pancreatic duct to induce ANP. The survival rate 24 h after inducing ANP was 33.3% in the nontreated group, versus 83.3 and 58.3% in the groups treated with OKY-046 and OP-2507, respectively. Only the group treated with OKY-046 showed significant improvement compared with the nontreated group. The plasma, pancreatic, and pulmonary TxB2 levels decreased significantly in the group treated with OKY-046, and the histopathological changes were not as severe. The levels of pancreatic and pulmonary cytosolic PLA2 activities decreased, and plasma and pancreatic secretory PLA2 activities also decreased. In conclusion, the levels of both types of PLA2 activity and TxA2 production decreased, and the survival rate improved as a result in the group treated with OKY-046, but OP-2507 had no effect on ANP. TxA2 and two types of PLA2 activity play an important role in the process of aggravation of acute pancreatitis.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Disease Models, Animal; Epoprostenol; Injections, Subcutaneous; Kidney; Lung; Male; Methacrylates; Pancreas; Pancreatitis, Acute Necrotizing; Phospholipases A; Phospholipases A2; Rats; Rats, Wistar; Survival Rate; Taurocholic Acid; Thromboxane A2; Thromboxane B2; Thromboxane-A Synthase; Time Factors

We investigated the effects of thromboxane (TX) A2 in rats with ischemia-reperfusion-induced intrauterine growth retardation. A saline solution or OKY-046, a selective TXA2 synthetase inhibitor, was injected into the caudal vein of pregnant rats on gestation day 17 before the induction of 60-min uteroplacental ischemia. The fetuses and placentas were delivered and examined on gestation day 21. Blood from the uterine vein of the occluded horn shortly after uteroplacental ischemia was collected, and plasma concentrations of TXB2 and 6-keto-prostaglandin (PG) F1 alpha were determined in the other rats on gestation day 17. Treatment with OKY-046 prevented the ischemia-induced reduction in the fetal body and placental weights. The ratio of 6-keto-PGF1 alpha to TXB2 was significantly increased in the OKY-046-treated group. We conclude that the action of TXA2 might play a salient role in our model.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Disease Models, Animal; Dose-Response Relationship, Drug; Embryonic and Fetal Development; Enzyme Inhibitors; Female; Fetal Growth Retardation; Injections, Intravenous; Methacrylates; Pregnancy; Random Allocation; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Thromboxane B2; Thromboxane-A Synthase

Monocrotaline (MCT)-induced pulmonary hypertension (PH) is a useful model for the investigation of this disorder in humans. The role of thrombocytes in the genesis of PH has already been addressed; however, the exact mechanism by which they induce PH remains to be elucidated. We investigated the effects of a thromboxane A2 (TXA2) synthase inhibitor (OKY-046) and a TXA2/prostaglandin H2 (PGH2) receptor antagonist (ONO-8809) on the development of MCT-induced PH. A single dose of MCT (60 mg/kg bodyweight; BW) was injected subcutaneously in Wistar rats 24 h after the administration of OKY-046 or ONO-8809. The TXA2 inhibitors were administered by gavage daily for 3 weeks. Urinary excretion of eicosanoids was determined by radioimmunoassay. At the end of the treatment period, the lungs, heart and kidneys were morphologically examined. The per cent medial thickness of the muscular pulmonary arteries (%MT) and the ratio of the right to the left ventricular mass including the septum (RV/LV + S) increased significantly in MCT-treated rats compared with the control rats. The %MT was attenuated by the administration of ONO-8809. Either OKY-046 or ONO-8809 attenuated the increase in RV/LV + S. In addition, both TXA2 inhibitors reduced urinary excretion of 11-dehydro-TXB2, particularly during the early phase of PH, suggesting that platelet aggregation was reduced. These findings suggest that the inhibition of TXA2 by synthase inhibition or receptor antagonism reduces or delays the development of MCT-induced PH in rats, probably by inhibiting platelet aggregation.

Topics: Animals; Bridged Bicyclo Compounds; Disease Models, Animal; Eicosanoids; Fatty Acids, Monounsaturated; Hypertension, Pulmonary; Male; Methacrylates; Monocrotaline; Prostaglandin Antagonists; Rats; Rats, Wistar; Reference Values; Thromboxane A2; Thromboxane-A Synthase

We examined the effects of eicosanoid antagonists on colonic damage induced by trinitrobenzene sulfonic acid (TNB) in a rat inflammatory bowel model. TNB (30 mg) dissolved in 0.25 ml of 50% ethanol, was given intrarectally. The appropriate doses of ONO-1078 (a leukotriene C4D4 antagonist), ONO-4057 (a leukotriene B4 antagonist), and OKY-046 (a thromboxane A2 synthetase inhibitor) were given to obtain the same blood level, either 4 h before (pre-treatment model) or 24 h after (the post-treatment model) the administration of TNB (n = 8 in all groups). Drugs were given once daily for 6 days through a gastric feeding tube. Autopsy was performed on the 7th day. Colonic damage was assessed in terms of colonic damage scores, and myeloperoxidase (MPO) activity and eicosanoid concentrations in colonic tissues were measured. Compared with the group given TNB alone, the colonic damage score was reduced to 10% in the pre-treatment model with ONO-1078, but the score was not reduced in other groups, MPO activity was not changed in any group. The concentration of leukotriene C4 was reduced with ONO-1078 treatment, in both pre- and post-treatment models. These results demonstrated that a leukotriene C4D4 antagonist reduced colonic inflammation; however, its anti-inflammatory effect was limited in this colitis model.

Topics: Animals; Chromones; Colon; Disease Models, Animal; Eicosanoids; Female; Inflammatory Bowel Diseases; Leukotriene C4; Leukotriene D4; Methacrylates; Peroxidase; Phenylpropionates; Rats; Rats, Sprague-Dawley; SRS-A; Thromboxane-A Synthase; Trinitrobenzenesulfonic Acid

Etodolac, which inhibits the activity of cyclooxygenase, did not affect antigen-induced contractions of the trachea and lung parenchyma of guinea pigs. Indomethacin tended to enhance antigen-induced contractions of the trachea and significantly enhanced contractions of the lung parenchyma. The inhibitory activity of AA-861, a 5-lipoxygenase inhibitor, in antigen-induced contractions of the trachea and lung parenchyma was more potent than that of ozagrel, a thromboxane A2 (TXA2) inhibitor. Thus, lipoxygenase products played a more important role than TXA2 in antigen-induced contractions of the trachea and lung parenchyma. These results suggest that the enhancement of antigen-induced contractions by indomethacin might be due to an increase in anaphylactic release of lipoxygenase products through the inhibition of cyclooxygenase. Since etodolac did not enhance antigen-induced contractions, we attempted to determine whether or not etodolac inhibits 5-lipoxygenase. Etodolac was found to have no effect on 5-lipoxygenase activity. Therefore, the low adverse effect of etodolac on antigen-induced contractions of the airway may be due to its weak inhibition of cyclooxygenase in the airway. These results suggest that etodolac would have only a very slight, if any, adverse effect on the airway in patients with asthma.

Topics: Animals; Asthma; Benzoquinones; Disease Models, Animal; Etodolac; Guinea Pigs; Immunization, Passive; Indomethacin; Isoantigens; Lipoxygenase Inhibitors; Lung; Methacrylates; Muscle Contraction; Muscle, Smooth; Rabbits; Serum Albumin, Bovine; Thromboxane A2; Trachea

We established an experimental model of late asthmatic response (LAR) using conscious guinea pigs actively sensitized by antigen aerosol inhalation. In actively sensitized guinea pigs, antigen challenge by aerosol inhalation caused an immediate increase in specific airway resistance (SRaw) (immediate airway response; IAR) followed by a LAR which occurred 4 to 8 hr after antigen challenge. SRaw in the challenged animals was still increased 23 hr after antigen challenge. Examination of bronchoalveolar lavage (BAL) fluid and histology of the lungs revealed increases in eosinophils and neutrophils during LAR. The beta-2 agonist salbutamol inhibited only IAR and not LAR. Dexamethasone inhibited LAR but not IAR. A low dose of theophylline had little effect on both IAR and LAR. A novel thromboxane A2 (TXA2) receptor antagonist, AA-2414, orally administered before antigen challenge dose-dependently inhibited both IAR and LAR, and oral administration of AA-2414 after the IAR inhibited LAR. Also, thromboxane synthetase inhibitors, CV-4151 and OKY-046, reduced both IAR and LAR. Salbutamol significantly reduced the increase in neutrophils in BAL fluid, and dexamethasone significantly reduced the increase in eosinophils and neutrophils in BAL fluid. Theophylline also reduced the increase in eosinophils in BAL fluid. However, AA-2414 did not inhibit the accumulation of these inflammatory cells in BAL fluid or the airway tissues. These results suggest that asthmatic responses in guinea pigs are similar to those in asthmatic subjects and that TXA2 plays an important role in both IAR and LAR but not in inflammatory cell infiltration in this model of allergic asthma.

Topics: Acetylcholine; Airway Resistance; Animals; Antibodies; Asthma; Benzoquinones; Bronchoalveolar Lavage Fluid; Disease Models, Animal; Fatty Acids, Monounsaturated; Guinea Pigs; Heptanoic Acids; Leukocytes; Male; Methacrylates; Ovalbumin; Pyridines; Theophylline; Thromboxane A2

Thromboxane A2 (TxA2) is a key mediator in the pathophysiology of severe burns and sepsis. This study was performed to assess the potential benefits of TxA2 synthetase inhibition and TxA2 receptor blockade in sepsis after severe thermal injury.. Pigs with left atrial, aortic, and pulmonary artery catheters received a 40 percent third-degree burn and, 24 hours later, 100 micrograms per kg Escherichia coli endotoxin. The antagonist treatment (BM) group was treated with the TxA2 receptor antagonist BM 13.177, the synthetase treatment (OKY) group with the TxA2 synthetase inhibitor OKY-046, and the control group received saline solution placebo. Another group without burn or endotoxin was used to assess the side effects of BM 13.177.. Both drugs significantly attenuated the changes in pulmonary vascular resistance index, cardiac index, arterial PO2, shunt, oxygen delivery, and oxygen consumption seen after endotoxin. However, cardiac index was significantly decreased in group BM before endotoxin. In healthy pigs, BM 13.177 decreased cardiac index and oxygen delivery and increased the pulmonary vascular resistance index.. TxA2 synthetase inhibitors and TxA2 receptor blockers are potentially useful in sepsis after severe burns. Comparison between drugs was complicated by the adverse effects of the antagonist, and further investigation with other antagonists is needed.

Topics: Animals; Blood Circulation; Blood Pressure; Burns; Cardiac Output; Disease Models, Animal; Endotoxins; Escherichia coli Infections; Female; Lipopolysaccharides; Lung; Methacrylates; Oxygen Consumption; Pulmonary Artery; Pulmonary Gas Exchange; Receptors, Thromboxane; Sulfonamides; Swine; Swine, Miniature; Thromboxane-A Synthase; Vascular Resistance

Topics: Animals; Arachidonic Acids; Disease Models, Animal; Dogs; Embolism, Fat; Epoprostenol; Female; Hypoxia; Indomethacin; Lung; Lung Injury; Male; Methacrylates; Microcirculation; Oleic Acid; Oleic Acids; Pulmonary Circulation; Pulmonary Embolism; Respiratory Distress Syndrome; Thromboxane A2; Vasoconstriction; Vasodilation

The anti-asthmatic effects of CS-518 (sodium 2-(1-imidazolylmethyl)-4,5-dihydrobenzo[b]thiophene-6-carboxylate) , a specific thromboxane A2 (TXA2) synthase inhibitor, were investigated in the ovalbumin-sensitized guinea pig asthmatic model. Although CS-518 slightly inhibited (about 25%) whole bronchoconstriction, it significantly inhibited the antigen-induced bronchoconstriction mediated by slow-reacting substance of anaphylaxis (SRS-A), which was not reduced by chlorpheniramine, a histamine H1 antagonist. On the other hand, indomethacin, a cyclooxygenase inhibitor, potentiated the SRS-A-mediated constriction. CS-518 strongly, and indomethacin slightly, suppressed the leukotriene D4-induced bronchoconstriction. CS-518 clearly inhibited the antigen-induced airway hyperresponsiveness, but this compound had no effect on the airway hyperresponsiveness induced by U-46619, a TXA2-mimetic agent, and propranolol. These results suggest that CS-518 suppresses the development of bronchoconstriction and airway hyperresponsiveness in asthmatic models by inhibition of TXA2 synthesis with the concomitant increase in bronchodilating prostaglandins such as prostaglandin E2 and prostaglandin I2.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Asthma; Bronchial Hyperreactivity; Bronchoconstriction; Chlorpheniramine; Disease Models, Animal; Guinea Pigs; Indomethacin; Male; Methacrylates; Ovalbumin; Propranolol; Prostaglandin Endoperoxides, Synthetic; SRS-A; Thiophenes; Thromboxane A2; Thromboxane-A Synthase; Vasoconstrictor Agents

Recently, thromboxane synthetase inhibitor has been used for the treatment of preeclampsia. In this study, we investigated the effects of thromboxane synthetase inhibitor (OKY-046) on placental blood flow (measured with clearance of hydrogen gas generated by electrolysis) in normotensive Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR). The systolic blood pressure of OKY-046-treated SHR (1, 4 and 8 mg/kg) decreased significantly (p < 0.05); however, the systolic blood pressure of WKY did not decrease. The placental blood flow of both OKY-046-treated WKY and SHR did not decrease. We found that OKY-046 has no reducing effect on placental blood flow in rats, and systolic blood pressure of SHR decreases. These data suggest that thromboxane synthetase inhibitor might have a beneficial effect on preeclampsia.

Topics: Animals; Blood Pressure; Body Weight; Disease Models, Animal; Dose-Response Relationship, Drug; Female; Fetus; Hypertension; Methacrylates; Organ Size; Placenta; Pregnancy; Pregnancy Complications, Cardiovascular; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Regional Blood Flow; Systole; Thromboxane-A Synthase

We attempted to obtain a new airway hyperresponsiveness model using DNP-Ascaris extract (DNP-Asc)-induced rat allergic asthma. Male Wistar rats were actively sensitized with DNP-Asc, and challenged in a non-anesthetized state by inhalation of the antigen for 10 min in a chamber. One, 6 and 24 hr after DNP-Asc challenge, the responsiveness of the airway smooth muscles to inhaled acetylcholine (ACh) was determined using a modified Konzett-Rössler method under anesthesia. Twenty four hr after the challenge, a significant and marked airway hyperresponsiveness was seen. The increase in airway responsiveness was significantly inhibited by pretreatments with a leukotriene antagonist, ONO-1078, and a thromboxane synthetase inhibitor, ozagrel, and tended to be inhibited by a PAF antagonist, CV-3988. The hyperresponsiveness induced by DNP-Asc challenge was accompanied by airway inflammation determined by dye exudation. From the above results, it is indicated that a model of airway hyperresponsiveness was established in rats with allergic asthma, and that the chemical mediators involved in the response might be leukotrienes, thromboxane A2 and PAF.

Topics: Acetylcholine; Animals; Ascaris; Asthma; Bronchial Hyperreactivity; Capillary Permeability; Chromones; Depression, Chemical; Dinitrophenols; Disease Models, Animal; Male; Methacrylates; Phospholipid Ethers; Platelet Activating Factor; Rats; Rats, Wistar; SRS-A; Thromboxane-A Synthase; Tissue Extracts

We have previously reported an increase in plasma levels of atrial natriuretic factor (ANF) in an ovine model of endotoxemia. The purpose of this study was to determine if this IR-ANF release was mediated by the increase of right atrial pressure (RAP) and right heart volumes concomitantly observed following endotoxin (LPS) administration. We studied right ventricular function, renal blood flow (RBF), urinary output (UO), urinary clearance of free water (CH20), urinary osmolality (UOSM), sodium excretion (UENA), and the plasma IR-ANF concentration (radioimmunoassay), following the administration of an E. coli LPS bolus (1 microgram/kg) with (group O, n = 8) and without (group E, n = 10) pretreatment with OKY-046, a selective thromboxane synthetase inhibitor. LPS induced early increases in RAP, right ventricular end-systolic (RVESV) and end-diastolic (RVEDV) volumes, heart rate (HR), and IR-ANF, and delayed increases in RBF, UO, and CH20. OKY-046 prevented the elevation of RAP, RVEDV, and RVESV; however, both groups showed virtually identical increases in IR-ANF (E: 20.03 +/- 3.8 to 192.33 +/- 35.47 pg/ml, O: 17.9 +/- 4.1 to 159.5 +/- 23 pg/ml) as well as an increase of HR, RBF, UO, and CH20. The increase in IR-ANF release noted following the administration of LPS in an ovine model does not appear to be related to the early elevations in right heart volumes or atrial distension.

Topics: Animals; Atrial Natriuretic Factor; Blood Pressure; Cardiac Output; Disease Models, Animal; Diuresis; Endotoxins; Heart Rate; Lipopolysaccharides; Methacrylates; Natriuresis; Osmolar Concentration; Renal Circulation; Sheep; Thromboxane-A Synthase; Toxemia; Urine; Vascular Resistance; Ventricular Function, Right

Topics: 4,5-Dihydro-1-(3-(trifluoromethyl)phenyl)-1H-pyrazol-3-amine; Animals; Arachidonate 5-Lipoxygenase; Arachidonic Acid; Arachidonic Acids; Bronchoalveolar Lavage Fluid; Diethylcarbamazine; Disease Models, Animal; Dogs; Ethchlorvynol; Indomethacin; Leukotrienes; Lung; Male; Methacrylates; Neutrophils; Pulmonary Edema; Respiratory Distress Syndrome; Tetradecanoylphorbol Acetate; Thromboxanes

In order to examine the functional changes in the vascular smooth muscle, the effects of a thromboxane A2 synthetase inhibitor (OKY-046) and a calcium channel blocker (diltiazem) on vessels following subarachnoid hemorrhage, and the contractile activity of cerebral vessels with various vasoactive agents, were investigated by studying isometric tension recordings in rings of cat basilar artery. The maximum contractile activities of the vessels in response to noradrenalin and adrenaline during the course of subarachnoid hemorrhage were significantly less than those in the control group. On the other hand, the maximum contractile activity of the vessels in response to prostaglandin F2 alpha on the seventh day following subarachnoid hemorrhage was significantly augmented compared with that in the control group. A significant decline in the relaxation of responsiveness to diltiazem during the course of subarachnoid hemorrhage was observed compared with that of diltiazem in the control group. This responsiveness to vasoactive agents was not influenced by the application of OKY-046. The present study reveals functional changes in vascular smooth muscle exposed to subarachnoid hemorrhage in response to vasoactive agents and a calcium entry blocker. Thromboxane A2 may not be a significantly influential factor in the present results. It is suggested that cerebral vasospasm may well be related to functional changes of the arterial wall, which appear to be associated with derangement of the mechanisms of smooth muscle constriction and dilatation based on organic changes.

Topics: Animals; Basilar Artery; Cats; Diltiazem; Dinoprost; Disease Models, Animal; Epinephrine; Methacrylates; Muscle Contraction; Muscle, Smooth, Vascular; Norepinephrine; Serotonin; Subarachnoid Hemorrhage; Thromboxane-A Synthase

We studied the inhibitory effects of OKY-046.HCl on PAF-induced airway hyperresponsiveness (AHR) in guinea pigs. 1) Inhalation of PAF (1 or 10 micrograms/ml) caused AHR to acetylcholine (ACh) aerosol and increased TXB2 generation in broncho-alveolar lavage fluid (BALF) at 30 min and 60 min, but the AHR and the TXB2 generation disappeared at 2 hr. OKY-046.HCl (100 mg/kg, intraduodenally) inhibited the AHR, which was accompanied by its inhibition of the TXB2 generation. However, no changes of 6-keto-PGF1 alpha in BALF were found. 2) There were no changes in the number of leukocytes; the activities of alkaline phosphatase, N-acetyl-beta-D-glucosaminidase, and lactate dehydrogenase; and the LTC4/D4/E4 in BALF. 3) In bronchus-lung preparations, PAF (1 microgram/min) also caused the AHR and increased TXB2 generation. OKY-046.HCl (100 micrograms/min) inhibited the AHR and TXB2 generation. 4) PAF (1 microgram/ml) evoked TXB2 generation in BALF from normal guinea pigs. OKY-046.HCl (10(-4)M) inhibited its increase. 5) Stable TXA2 (STA2, 1 ng/ml) inhalation also caused AHR to ACh at 30 min. STA2 (0.45 ng/min) also caused the AHR in bronchus-lung preparations. These results suggest that OKY-046.HCl can inhibit PAF-induced AHR by suppressing the generation of TXA2. We also supposed that TXA2 is released from lung parenchyma, airway epithelium and cell components in BALF.

Topics: Acrylates; Animals; Asthma; Bronchoalveolar Lavage Fluid; Disease Models, Animal; Guinea Pigs; In Vitro Techniques; Male; Methacrylates; Platelet Activating Factor; Thromboxane A2; Thromboxane-A Synthase

To elucidate the possible involvement of thromboxane A2 (TxA2) in airway hyperresponsiveness, we examined the effect of OKY-046, a potent and selective inhibitor of TxA2 synthetase, on airway hyperresponsiveness induced by ozone exposure in dogs. Ozone exposure (3 ppm, 2 hr) markedly increased airway responsiveness to inhaled methacholine without affecting basal respiratory resistance. Although ozone also caused a slight but significant increase in neutrophil number in the bronchoalveolar lavage fluid, there was no correlation between the level of airway hyperresponsiveness and increased neutrophil number. Although OKY-046 significantly inhibited the increases in airway hyperresponsiveness in a dose-dependent manner at doses ranging from 100 to 300 mg/kg, p.o., the compound did not affect the basal airway responsiveness and respiratory resistance at 300 mg/kg, p.o. Inhalation of the subthreshold concentration (i.e., the highest dose which did not cause bronchoconstriction) of STA2 (a stable TxA2 mimetic agent) elicited a significant increase in airway responsiveness to methacholine. These results suggest that TxA2 may play a role in mediating ozone-induced airway hyperresponsiveness. However, the accumulation of neutrophils in the airway lumen may not be essential for the development of airway hyperresponsiveness.

Topics: Acrylates; Animals; Asthma; Disease Models, Animal; Dogs; Dose-Response Relationship, Drug; Female; Methacrylates; Ozone; Thromboxane A2; Thromboxane-A Synthase

Reperfusion of ischemic tissue is responsible for production of metabolites with deleterious local vascular effects. Thromboxane A2, a potent vasoconstrictor and platelet aggregator, has been implicated as a mediator of the "reperfusion injury." We studied the effect of an experimental thromboxane synthetase inhibitor, OKY-046, on coronary sinus thromboxane levels, ventricular irritability, myocardial contractility, infarct salvage, and histologic features of reperfusion. Sixteen sheep were randomized to OKY-046, 3 mg/kg, or saline vehicle before 3-hour occlusion and subsequent reperfusion of the left anterior descending artery. The OKY group demonstrated less ventricular irritability as measured by incidence of ventricular fibrillation and necessity for countershock to reverse tachyarrhythmias. Coronary sinus thromboxane levels were significantly lower in the OKY group compared with the control group. There is additional evidence to suggest that OKY increases infarct salvage and attenuates histologic features of microcirculatory damage.

Topics: 6-Ketoprostaglandin F1 alpha; Acrylates; Animals; Coronary Circulation; Coronary Disease; Disease Models, Animal; Methacrylates; Microcirculation; Myocardial Contraction; Random Allocation; Sheep; Thromboxane B2; Thromboxane-A Synthase; Ventricular Fibrillation

Accelerated anti-glomerular basement membrane nephritis was induced in rabbits, and the immunological, clinical and histological evolution studied in relation to urinary immunoreactive thromboxane B2 (i-TXB2) and immunoreactive prostaglandin E2 (i-PGE2) excretion. In control nephritic animals, urinary i-TXB2 increased 5-fold on day +1, but was normal again by day +5. The urinary i-TXB2 showed a positive correlation with creatinine clearance (CCr), proteinuria and anti-sheep immunoglobulin antibody. Urinary i-PGE2 excretion increased by 50% on day +1, but was indistinguishable later from controls. The effects of the specific thromboxane synthetase inhibitor OKY-046 on this model was studied. In non-nephritic control animals, OKY-046 did not affect the CCr, the urinary protein excretion or the number of monocytes in glomeruli but reduced the excretion of i-TXB2. Although OKY-046 markedly inhibited the i-TXB2 excretion throughout the experiment in nephritic animals, the creatinine clearances were significantly worse, the proteinuria greater, and the number of infiltrating monocytes greater at day +5; by day +10 there was no difference from controls. There was no evidence that TXB2 is involved in the induction of proteinuria, and increased PGE2 synthesis did not protect against later proteinuria and fall in creatinine clearance. Inhibition of thromboxane synthetase appears to make this model of nephritis worse, rather than better.

Topics: Acrylates; Animals; Basement Membrane; Creatinine; Depression, Chemical; Dinoprostone; Disease Models, Animal; Female; Immunoenzyme Techniques; Immunoglobulin G; Kidney Glomerulus; Methacrylates; Nephritis; Prostaglandins E; Rabbits; Thromboxane B2; Thromboxane-A Synthase

The authors have previously reported a model of ischemic bowel necrosis produced in the rat by synthetic platelet-activating factor (PAF) or a combination of PAF and bacterial endotoxin. Because rat platelets are refractory to PAF and thromboemboli were not found in the mesenteric or intestinal microvasculature, they suspected that secondary mediators were involved in the pathogenesis of bowel necrosis. They have found the following lipoxygenase products of arachidonic acid, especially leukotrienes (LT), probably played an important role in the pathogenesis of bowel necrosis, because diethylcarbamazine (an inhibitor for LTA synthesis) and FPL55712 (LT antagonist) ameliorated, and at times completely prevented, the lesions. NDGA (a nonspecific lipoxygenase inhibitor) was less effective, probably because of its additional effect on cyclooxygenase inhibition. Verapamil, a calcium channel blocker, ameliorated the disease. Thromboxane A2, a potent vasoconstrictor, was probably not responsible for the ischemia of the gastrointestinal tract. This is suggested by the ineffectiveness of OKY-046 in preventing bowel necrosis. Prostaglandin (PG) E1 infusion often prevented the bowel necrosis, which suggested beneficial effects of vasodilating PGs, probably released as a defense mechanisms. Indomethacin aggravated the disease, probably by inhibiting PG release and shifting the metabolic pathway toward the lipoxygenase pathway. Antihistamine and antiserotonin had no effect, which suggested that these mediators were not involved in the pathogenesis of bowel necrosis. Shock produced by PAF was probably not the only cause of bowel necrosis, because reversal of the hypotension did not always prevent the development of bowel necrosis. Hemoconcentration (increased vasopermeability) and leukopenia induced by PAF did not correlate with the development or severity of bowel necrosis.

Topics: Alprostadil; Animals; Blood Pressure; Catechols; Chromones; Diethylcarbamazine; Disease Models, Animal; Hematocrit; Indomethacin; Intestines; Ischemia; Leukocyte Count; Lipopolysaccharides; Lipoxygenase Inhibitors; Male; Masoprocol; Methacrylates; Necrosis; Platelet Activating Factor; Rats; Rats, Inbred Strains; Salmonella typhi; Thromboxane-A Synthase; Verapamil