l-663536 and verlukast

Topics: Animals; Asthma; Glomerulonephritis; Humans; Hydroxyurea; Indoles; Inflammatory Bowel Diseases; Leukotriene Antagonists; Leukotrienes; Membrane Proteins; Propionates; Psoriasis; Quinolines; Receptors, Leukotriene

A potent, selective and orally active receptor antagonist of leukotriene D4, MK-571, was discovered and developed from a styrylquinoline lead structure based on a hypothetical model of the leukotriene D4 receptor. MK-571 blocks the action of LTD4 in animals and man, and is effective in a number of animal models of antigen-induced bronchoconstriction at plasma concentration at or below 2 micrograms/mL. MK-571 also blocks antigen-induced asthmatic responses in man. In addition a series of 2-indolealkanoic acids was discovered to be inhibitors of leukotriene biosynthesis. From this series, MK-886, a nanomolar inhibitor of leukotriene biosynthesis was developed. The mechanism of action of MK-886 has been found to be the inhibition of activation of the 5-lipoxygenase enzyme. This inhibition is mediated by interaction with a specific 18 kD protein termed 5-lipoxygenase activating protein (FLAP). MK-886 is an inhibitor of leukotriene biosynthesis and of antigen-induced bronchoconstriction in animal models and in asthmatic men.

Topics: Animals; Asthma; Chemistry, Pharmaceutical; Clinical Trials as Topic; Humans; Indoles; Leukotriene Antagonists; Propionates; Quinolines; SRS-A; Structure-Activity Relationship

Topics: 5-Lipoxygenase-Activating Proteins; Animals; Carrier Proteins; Humans; Indoles; Leukotriene Antagonists; Membrane Proteins; Propionates; Quinolines; Receptors, Immunologic; Receptors, Leukotriene; Research; Thromboxanes

Topics: Animals; Arachidonate 5-Lipoxygenase; Arachidonate Lipoxygenases; Arachidonic Acid; Arachidonic Acids; Bronchial Diseases; Constriction, Pathologic; Humans; Indoles; Lipoxygenase Inhibitors; Molecular Structure; Propionates; Quinolines; Receptors, Immunologic; Receptors, Leukotriene

Topics: 5-Lipoxygenase-Activating Proteins; Animals; Arachidonate 5-Lipoxygenase; Asthma; Bronchoconstriction; Carrier Proteins; Depression, Chemical; Double-Blind Method; Enzyme Activation; Guinea Pigs; Humans; Indoles; Leukotrienes; Lipoxygenase Inhibitors; Membrane Proteins; Propionates; Protein Processing, Post-Translational; Quinolines; Receptors, Immunologic; Receptors, Leukotriene; SRS-A

Bronchial asthma continues to be a big challenge to therapy. Mast cells play an important role in allergic asthma. Histamine and leukotrienes are established mast cell mediators, but antihistamines currently play no role in asthma therapy.. Human bronchial strips were exposed to the mast cell activator compound 48/80 (200 μg/ml) in isolated organ experiments.. The contractile response was not inhibited by the H1 receptor antagonist antihistamine chloropyramine (0.3 μmol/l), the leukotriene cys-LT1 receptor antagonist MK 571 (3 μmol/l), the 5-lipoxygenase inhibitor MK 886 (5 μmol/l), the cyclo-oxygenase inhibitor indomethacin (5 μmol/l), tetrodotoxin, or atropine. Chloropyramine, combined with either MK 571 or MK 886 significantly reduced the response.. A supra-additive effect is proposed for the antihistamine and the anti-leukotrienes, which might have relevance to human asthma therapy as well; such a combination deserves a large-scale clinical study. These data also indicate that substances like compound 48/80 should be denoted as mast cell activators rather than 'histamine liberators'.

Topics: Bronchi; Drug Synergism; Ethylenediamines; Histamine H1 Antagonists; Humans; In Vitro Techniques; Indoles; Isotonic Contraction; Leukotriene Antagonists; Lipoxygenase Inhibitors; p-Methoxy-N-methylphenethylamine; Propionates; Quinolines; Receptors, Histamine H1; Receptors, Leukotriene

This study investigated endogenous mediators involved in mosquito allergy-associated itching in mice. An intradermal injection of an extract of mosquito salivary gland elicited marked scratching in sensitized mice. The 5-lipoxygenase inhibitor zileuton (100 mg/kg), the 5-lipoxygenase activating peptide inhibitor MK-886 (10 mg/kg), and the glucocorticoid betamethasone 17-valerate (3 mg/kg) inhibited the scratching. The scratching was not affected by the cyclooxygenase inhibitors indomethacin and ketoprofen, the TP prostanoid receptor antagonist SQ-29548, the leukotriene B(4) antagonist ONO-4057, the cysteinyl leukotriene antagonist pranlucast, the leukotriene D(4) antagonist MK-571, the platelet-activating factor antagonist CV-3988, the nitric oxide synthase inhibitor N(G)-nitro-L-arginine methyl ester, the H(2) histamine-receptor antagonist cimetidine, the H(1) histamine-receptor antagonist terfenadine plus cimetidine, and cypoheptadine that blocks the 5-HT(1/2) serotonin receptors. Zileuton (100 mg/kg) inhibited the increased activity of the cutaneous nerve branch induced by an intradermal injection of the extract, suggesting the peripheral action. Zileuton and MK-886 (10 and 100 microM) did not affect high K(+)-induced increase in intracellular Ca(2+) concentration in cultured dorsal root ganglion neurons. The results suggest that 5-lipoxygenase metabolite(s) other than leukotriene B(4) and cysteinyl leukotrienes are involved in mosquito allergy-associated itching.

Topics: Animals; Arachidonate 5-Lipoxygenase; Betamethasone Valerate; Bridged Bicyclo Compounds, Heterocyclic; Calcium; Chromones; Cimetidine; Culicidae; Dose-Response Relationship, Drug; Fatty Acids, Unsaturated; Hydrazines; Hydroxyurea; Hypersensitivity; Indoles; Indomethacin; Ketoprofen; Leukotriene B4; Lipoxygenase Inhibitors; Male; Mice; Mice, Inbred ICR; NG-Nitroarginine Methyl Ester; Phenylpropionates; Phospholipid Ethers; Propionates; Pruritus; Quinolines; Terfenadine

Cysteinyl leukotrienes (cysLT) are pro-inflammatory and vasoactive products suspected to be involved in the regulation of vascular tone and blood pressure in hypertension.. We investigated, in spontaneously hypertensive rats (SHR), the involvement of cysLT in the in-vivo regulation of blood pressure and the in-vitro endothelium-dependent contraction to acetylcholine in isolated aorta.. SHR and Wistar-Kyoto rats (WKY) were orally treated for 3 weeks with either the cysLT biosynthesis inhibitor MK-886 (0.1 mg/ml) or vehicle. After mean arterial blood pressure (MABP) measurement, aortic ring preparations were removed from all groups of animals, and contractions and relaxations were monitored subsequent to stimulation with acetylcholine.. MABP was higher in SHR. Chronic treatment with MK-886 did not alter MABP in either SHR or WKY. In the presence of the N-nitro-L-arginine (L-NA, 100 micromol/l), and on prostaglandin F2alpha (PGF2alpha)-induced tone, acetylcholine evoked concentration-dependent contractions in intact aortic rings from SHR only. Pretreatment with either MK-886 (10 micromol/l), the 5-lipoxygenase (5-LO) inhibitor AA861 (10 micromol/l), or the cysLT1 receptor antagonist MK571 (1 micromol/l) reduced (P < 0.05) acetylcholine-induced contractions in intact aortic rings from SHR only. Acetylcholine-induced contractions were weaker (P < 0.01) in SHR chronically treated with MK-886 than in SHR. In the presence of L-NA, leukotriene (LT) D4 induced greater (P < 0.05) concentration-dependent contractions in aortic rings from SHR than from WKY. MK571 abolished LTD4-evoked contractions.. These data suggested that 5-LO-derived products, through the activation of cysLT1 receptors, could be involved in the endothelium-dependent contraction to acetylcholine in aorta from SHR but not in the regulation of MABP in SHR.

Topics: Acetylcholine; Animals; Aorta, Thoracic; Arachidonate 5-Lipoxygenase; Benzoquinones; Biopterins; Blood Pressure; Body Weight; Dinoprost; Endothelium, Vascular; Hypertension; Indoles; Leukotriene D4; Lipoxygenase Inhibitors; Male; Membrane Proteins; Nitroarginine; Propionates; Quinolines; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Receptors, Leukotriene; Vasoconstriction

Stem cell factor (SCF) is directly involved in the induction of airway hyperreactivity during allergen-induced pulmonary responses in mouse models. In these studies, we examined the specific mediators and mechanisms by which SCF can directly induce airway hyperreactivity via mast cell activation. Initial in vitro studies with bone marrow-derived mast cells indicated that SCF was able to induce the production of bronchospastic leukotrienes, LTC(4) and LTE(4). Subsequently, when SCF was instilled in the airways of naive mice, we were able to observe a similar induction of LTC(4) and LTE(4) in the bronchoalveolar lavage (BAL) fluid and lungs of treated mice. These in vivo studies clearly suggested that the previously observed SCF-induced airway hyperreactivity may be related to the leukotriene production after SCF stimulation. To further investigate whether the released leukotrienes were the mediators of the SCF-induced airway hyperreactivity, an inhibitor of 5-lipoxygenase (5-LO) binding to the 5-LO activating protein (FLAP) was utilized. The FLAP inhibitor MK-886, given to the animals before intratracheal SCF administration, significantly inhibited the release of LTC(4) and LTE(4) into the BAL fluid. More importantly, use of the FLAP inhibitor nearly abrogated the SCF-induced airway hyperreactivity. In addition, blocking the LTD(4)/E(4), but not LTB(4), receptor attenuated the SCF-induced airway hyperreactivity. In addition, the FLAP inhibitor reduced other mast-derived mediators, including histamine and tumor necrosis factor. Altogether, these studies indicate that SCF-induced airway hyperreactivity is dependent upon leukotriene-mediated pathways.

Topics: Animals; Arachidonate 5-Lipoxygenase; Benzopyrans; Carboxylic Acids; Cells, Cultured; Female; Histamine; Indoles; Leukotriene Antagonists; Leukotriene C4; Leukotriene D4; Leukotriene E4; Leukotrienes; Lipoxygenase Inhibitors; Mast Cells; Methacholine Chloride; Mice; Propionates; Quinolines; Respiratory Hypersensitivity; Signal Transduction; Stem Cell Factor; Tumor Necrosis Factor-alpha

It has been reported that hyperpnea-induced bronchoconstriction in guinea pigs is a potential model for exercise-induced asthma in humans. We hypothesized that calcitonin gene-related peptide (CGRP) could modulate leukotriene D4 (LTD4)-induced responses and be involved in the pathophysiology in this asthma model. We measured tracheal (Ptr) and alveolar pressure (PA) using alveolar capsules in open-chested, mechanically ventilated (f = 1 Hz, VT = 9 ml/kg, PEEP = 4 cm H2O) guinea pigs. Animals were intravenously pretreated with saline (SAL), CGRP(8-37) (CGRP receptor antagonist), CGRP, MK-571 (LTD4 receptor antagonist), MK-886 (5-lipoxygenase inhibitor), or CGRP(8-37) + MK-571, and then underwent dry gas hyperpnea challenge (HC, 95% 02-5% CO2, 150 breaths/min, 7 min). We calculated resistance of lung (RL), tissue (Rti), and airway (Raw). HC increased RL, Rti, and Raw in SAL controls (322 +/- 27, 430 +/- 59, 299 +/- 23% baseline, respectively). MK-571, MK-886, and CGRP significantly reduced the responses to HC, while CGRP(8-37) enhanced HC-induced responses. Pretreatment with CGRP(8-37) and MK-571 in combination attenuated HC-induced constriction. In addition, pretreatment with CGRP reduced responses induced by intravenous administration of LTD4. These observations suggest that CGRP might be involved in the pathophysiology of hyperpnea-induced constriction in guinea pigs via modulation of LTD4-elicited responses.

Topics: Animals; Asthma, Exercise-Induced; Bronchoconstriction; Bronchodilator Agents; Calcitonin Gene-Related Peptide; Drug Interactions; Guinea Pigs; Hyperventilation; Indoles; Leukotriene D4; Lipoxygenase Inhibitors; Male; Miotics; Models, Biological; Peptide Fragments; Positive-Pressure Respiration; Propionates; Quinolines; Respiration, Artificial

We have recently demonstrated that tissue resistance increases during the early response (ER) to antigen challenge in sensitized Brown-Norway rats. The purpose of the present study was to investigate the in vitro airway and tissue responses to antigen and the involvement of the potential mediators serotonin (5-HT) and leukotriene D4 (LTD4). We sensitized Brown-Norway rats with ovalbumin (OA) and subsequently challenged bronchial rings and subpleural parenchymal strips with OA in the organ bath. In selected experiments tissues were incubated with methysergide (a 5-HT receptor antagonist), ketanserin (a 5-HT2 receptor antagonist), MK-571 (a LTD4 receptor antagonist), or MK-886 (5-lipoxygenase inhibitor) prior to challenge. Both bronchial rings and parenchymal strips constricted in response to OA. Methysergide and ketanserin completely inhibited OA-induced constriction of bronchial rings. The effect of MK-571 was not significant, whereas MK-886 partially blocked OA-induced bronchial constriction, suggesting a potential role for LTC4 in antigen-induced airway constriction. In parenchymal strips, methysergide, ketanserin, MK-571, and MK-886 all partially inhibited the OA response, whereas the combinations of methysergide and MK-571 or ketanserin and MK-886 completely ablated the response. These data suggest that both bronchial rings and parenchymal strips constrict after OA challenge but that the relative contributions of 5-HT and LTD4 to the allergic response in central airways and parenchymal tissues differ.

Topics: Airway Resistance; Animals; Bronchi; Bronchial Provocation Tests; Bronchoconstriction; Indoles; Ketanserin; Leukotriene D4; Lipoxygenase Inhibitors; Lung; Methysergide; Ovalbumin; Propionates; Quinolines; Rats; Rats, Inbred BN; Receptors, Immunologic; Respiratory Hypersensitivity; Serotonin

Topics: Bronchi; Bronchoconstriction; Humans; Hydroxyeicosatetraenoic Acids; Indoles; Leukotriene Antagonists; Leukotrienes; Monocytes; Muscle, Smooth; Propionates; Quinolines

Several very selective leukotriene inhibitors, and a PAF inhibitor, suitable for in vivo use, have been tested for their effects on hyperbaric oxygen toxicity. The leukotriene D4 inhibitor, L660771, and the 5-lipoxygenase pathway inhibitor L663536, failed to affect convulsions or lung damage induced by hyperbaric oxygen (pressure range 515-615 kPa) in either rats or mice. The specific PAF antagonist L659989 showed marginal protection against hyperoxic convulsions and did not alter pulmonary damage. The specific LTB4 antagonist SC-41930 was very effective in inhibiting hyperbaric oxygen-induced convulsions in both rats and mice. SC-41930 also very significantly protected rats against pulmonary oxygen toxicity, but had only marginally significant effects on pulmonary protection in mice.

Topics: Animals; Benzopyrans; Female; Furans; Indoles; Leukotriene B4; Leukotrienes; Lipoxygenase Inhibitors; Lung; Male; Mice; Mice, Inbred BALB C; Oxygen; Platelet Activating Factor; Pressure; Propionates; Quinolines; Rats; Seizures; Specific Pathogen-Free Organisms; SRS-A

We have used a tracheal tube preparation to study antigen-induced contraction in sensitized guinea pig airways. Treatment with both the cyclooxygenase inhibitor indomethacin and the lipoxygenase inhibitor MK-886 (L-663,536) affected this contraction in preparations with intact epithelium. Indomethacin potentiated and MK-886 inhibited part of the contraction. Leukotriene release from tracheal tubes was measured after antigen challenge, and was found to be significant in preparations with an intact epithelium. When the epithelium was removed, the histamine receptor antagonist mepyramine reduced antigen-induced contraction by 90%. Our results show that when the epithelium is absent, histamine is the most important mediator in the contraction. With the epithelium left intact, the contraction is more complex: both the cyclooxygenase and lipoxygenase pathways are involved, and our findings indicate that eicosanoid production is associated with the airway epithelium.

Topics: Animals; Antigens; Eicosanoids; Epithelium; Female; Guinea Pigs; Histamine; Indoles; Indomethacin; Leukotriene Antagonists; Leukotrienes; Muscle Contraction; Muscle, Smooth; Propionates; Pyrilamine; Quinolines; Trachea

The present study was designed to determine the role of leukotrienes in aspirin-induced acute gastric mucosal injury in rats. We examined the effects of aspirin, indomethacin, and sodium salicylate on gastric mucosal injury, and on eicosanoid synthesis and content. Aspirin, indomethacin, and acidified salicylate caused significant mucosal injury, while salicylate at pH 7 did not induce significant injury. Aspirin and indomethacin significantly reduced mucosal prostaglandin synthesis and content. No significant changes in mucosal leukotriene C4 synthesis and content were observed. There were no correlations between changes in mucosal leukotriene B4 synthesis and the extent of mucosal injury. We also evaluated the effects of MK-571 (a leukotriene D4 receptor antagonist) and MK-886 (a leukotriene biosynthesis inhibitor) on aspirin-induced gastric mucosal injury. Neither MK-571 nor MK-886 could reduce the mucosal lesions induced by aspirin. These findings suggest that leukotrienes are not involved in aspirin-induced acute gastric mucosal injury in rats.

Topics: Acute Disease; Animals; Aspirin; Gastric Mucosa; Indoles; Indomethacin; Leukotriene Antagonists; Leukotrienes; Male; Propionates; Quinolines; Rats; Rats, Inbred Strains; Sodium Salicylate; SRS-A