verlukast and Constriction--Pathologic

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

The ovalbumin (OA)-sensitized Brown Norway rat (BN) demonstrates early-response (ER) and late-response (LR) allergic bronchoconstriction. To determine whether these responses could be replicated in vitro, we studied lung explants from 8-wk-old male BN rats (wt: 239 +/- 28 g), of which 19 were sensitized to OA (test) and 16 served as controls. Two weeks after sensitization, the animals' lungs were removed, filled with a 1% (wt/vol) agarose-containing solution at 37 degrees C, and cooled to 4 degrees C. Transverse slices (0.5 to 1.0 mm thick) were cut and cultured overnight. Airways were visualized with an inverted microscope and baseline images were obtained with a video camera. To study the ER, 40 airways from 15 test rats and 29 airways from 10 control rats were challenged with 2 micrograms OA and imaged each minute for 10 min. To study the LR, 40 airways from 12 test rats and 44 airways from 12 control rats were challenged with 2 micrograms OA and imaged each hour for 8 h. The maximal response (MR) for each airway was defined as the percent of airway closure. The ER and LR were both defined as an MR > or = mean + 2 SD of the controls. An ER occurred in 38 of 40 test and 2 of 29 control airways (mean MR: 42 +/- 24% versus 4 +/- 3%, p < 0.001), and was completely blocked by methysergide pretreatment in 13 airways.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Airway Resistance; Animals; Asthma; Bronchial Provocation Tests; Bronchodilator Agents; Constriction, Pathologic; Disease Models, Animal; Drug Hypersensitivity; Hypersensitivity, Delayed; Hypersensitivity, Immediate; Immunoglobulin E; In Vitro Techniques; Leukotriene D4; Male; Methysergide; Ovalbumin; Premedication; Propionates; Quinolines; Rats; Serotonin; Time Factors

Continuous intravenous infusions of leukotriene D4 produced a prolonged but variable bronchoconstriction (approximately a 200% increase in lung resistance (RL) and a 50% decrease in dynamic compliance (Cdyn] in anesthetized and paralysed guinea pigs that peaked within 1-1.5 min and was followed by a somewhat smaller secondary plateau response. The overall response was delayed (time to peaks) but not significantly reduced by pretreatment with the cyclooxygenase inhibitor indomethacin (1 mg/kg), was markedly potentiated by the beta-adrenoceptor antagonist timolol (5 micrograms/kg), and was partially and completely blocked by pretreatment with 0.1 and 1.0 mg/kg, respectively, of the leukotriene D4 receptor antagonist MK-571. MK-571 prevented the response in indomethacin-treated guinea pigs but was considerably more active at preventing and reversing the potentiated responses (lower dose of leukotriene D4) in animals treated with indomethacin and timolol. Additional studies in indomethacin- and timolol-treated animals demonstrated that MK-571 was active with good duration of action by the aerosol route of administration (30 min and 4 h pretreatment). The technique of infusing leukotrienes into untreated, indomethacin-treated, and indomethacin- and timolol-treated guinea pigs is a useful method to study the action and interaction of leukotriene receptor antagonists.

Topics: Aerosols; Anesthesia; Animals; Bronchi; Constriction, Pathologic; Guinea Pigs; Indomethacin; Infusions, Intravenous; Male; Propionates; Quinolines; SRS-A; Timolol