Effect of an orally active Th2 cytokine inhibitor, suplatast on "atopic cough" tosilate.

BACKGROUND: "Atopic cough" is a new clinical entity that presents with isolated chronic bronchodilator-resistant cough accepted in the Japanese Respiratory Society Guidelines for Management of Cough. The essential features are eosinophilic tracheobronchitis, increased cough reflex sensitivity and an atopic constitution. It has been suggested that activated helper T lymphocytes and the cytokines which are produced by these cells are involved in the pathogenesis, but the relationship between helper T cell-derived cytokines and the airway cough reflex sensitivity remains unknown. METHODS: The effect of an orally active Th2 cytokine inhibitor, suplatast tosilate (CAS 94055-76-2, IPD; 300 mg/day), on the cough response to inhaled capsaicin (CAS 404-86-4) was examined in ten patients with atopic cough. The capsaicin cough threshold, defined as the lowest concentration of capsaicin eliciting five or more coughs, was measured as an index of airway cough reflex sensitivity. The serum total immunoglobulin E (IgE) level and the peripheral blood eosinophil count were also determined after treatment with suplatast tosilate. RESULTS: The cough threshold measured after four weeks of treatment with suplatast tosilate was significantly increased compared to the value obtained with placebo, along with a decrease of the serum IgE level and peripheral eosinophil count. CONCLUSIONS: Th2 cytokines may increase the airway cough reflex sensitivity in patients with atopic cough. Oral administration of suplatast tosilate may be a novel therapy for atopic cough.

Sputum eosinophilia, airway hyperresponsiveness and airway narrowing in young adults with former asthma.

BACKGROUND: 30-80% of outgrown asthma subjects develop symptoms again later in life. We investigated inflammation and function of lower airway in adolescents with former asthma. METHODS: 326 never-smoking young adults (mean age 24.0 years) were interviewed with special emphasis on history of asthma. Diagnosis of asthma was based on GINA guidelines. Former asthma subjects consisted of ones with a history of physician-diagnosed childhood asthma, who had been free of asthma symptoms without the use of medication for at least 10 years prior to the study. Provocative concentration of methacholine causing a 20% fall in forced expiratory volume in 1 second (FEV(1))(PC(20)) and eosinophil percentage in induced sputum were measured. RESULTS: 31 subjects were former asthma subjects (FBA), 11 subjects were current asthma subjects (CBA) and 284 subjects had no history of asthma (non-BA). PC(20) and FEV(1)/FVC ratio were significantly lower in the FBA group than in the non-BA group (P < 0.01). Maximal mid-expiratory flow (MMF) was significantly lower in the FBA group than in the non-BA group (P < 0.05). Sputum eosinophil percentage was significantly increased in the FBA group compared with the non-BA group (P < 0.01). PC(20) was significantly lower in the CBA group than in the FBA and non-BA groups (P < 0.01). FEV(1), FEV(1)/FVC ratio and MMF were significantly lower in the CBA group than in the FBA group (P < 0.05, P < 0.05 and P < 0.05, respectively) and the non-BA group (P < 0.01, P < 0.01 and P < 0.05, respectively). Sputum eosinophils were significantly higher in the CBA group than in the FBA and non-BA groups (P < 0.01). CONCLUSIONS: This study shows that subjects with long-term outgrown asthma continue to have airway eosinophilic inflammation, airway hyperresponsiveness and airway narrowing.

Proton pump inhibitor-responsive chronic cough without acid reflux: a case report.

BACKGROUND: Because 24-h esophageal pH monitoring is quite invasive, the diagnosis of gastroesophageal reflux disease (GERD)-associated cough has usually been made based merely on the clinical efficacy of treatment with proton pump inhibitor (PPI). CASE PRESENTATION: We recently encountered two patients with PPI-responsive chronic non-productive cough for whom switching from bronchodilators and glucocorticosteroids to PPI resulted in improvement of cough. The cough returned nearly to pre-administration level a few weeks after discontinuation of PPI. Though GERD-associated cough was suspected, 24-h esophageal pH monitoring revealed that the cough rarely involved gastric acid reflux. Following re-initiation of PPI, the cough disappeared again. CONCLUSION: PPI may improve cough unrelated to gastric acid reflux.

Bi-weekly administration of gemcitabine plus vinorelbine in elderly patients with advanced non-small-cell lung cancer: multicenter phase II trial.

PURPOSE: Gemcitabine (GEM) and vinorelbine (VNR) have demonstrated activity as a first-line treatment in elderly patients with advanced non-small-cell lung cancer (NSCLC). We conducted a multicenter phase II trial to evaluate the efficacy and toxicity of bi-weekly administration of GEM plus VNR in elderly patients with advanced NSCLC. PATIENTS AND METHODS: Forty-six chemotherapy-naive elderly (age: >or=70 years) NSCLC patients were enrolled. Patients were eligible if they had histologically or cytologically confirmed unresectable NSCLC with measurable and/or assessable disease. Patients received GEM (1000 mg/m2) and VNR (25 mg/m2) every 2 weeks. RESULTS: The objective response rate of this treatment was 22.7% (95% confidence interval (CI), 10.3-35.1%), median survival time was 310 days, and median time to progression was 133 days. The one-year survival rate was 40.9% (95% CI, 26.3-55.4%), and most adverse events were mild. Only three (6.8%) patients needed to omit GEM because of grade 4 neutropenia or due to physician judgment. No patients suffered treatment-related death. CONCLUSIONS: Bi-weekly administration of GEM plus VNR in elderly patients was an effective, feasible and well-tolerated treatment schedule.

Prostaglandin I2 enhances cough reflex sensitivity to capsaicin in the asthmatic airway.

Inflammatory mediators are involved in the pathogenesis of airway inflammation, but the role of prostaglandin I2 (PGI2) remains obscure. This study was designed to investigate the role of PGI2 in cough reflex sensitivity of the asthmatic airway, which is characterized by chronic eosinophilic airway inflammation. The effect of beraprost, a chemically and biologically stable analogue of PGI2, on cough response to inhaled capsaicin was examined in 21 patients with stable asthma in a randomized, placebo-controlled cross over study. Capsaicin cough threshold, defined as the lowest concentration of capsaicin eliciting five or more coughs, was measured as an index of airway cough reflex sensitivity. The cough threshold was significantly (p < 0.05) decreased after two weeks of treatment with beraprost [17.8 (GSEM 1.20) microM] compared with placebo [30.3 (GSEM 1.21) microM]. PGI2 increases cough reflex sensitivity of the asthmatic airway, suggesting that inhibition of PGI2 may be a novel therapeutic option for patients with asthma, especially cough predominant asthma.

Longitudinal changes of pulmonary function and bronchial responsiveness in cough-variant asthma treated with bronchodilators alone.

Cough due to cough-variant asthma (CVA) responds well to bronchodilators such as beta 2 adrenergic agonists. The aim of this study was to assess longitudinal changes of pulmonary function and bronchial responsiveness in CVA, which was treated with bronchodilators alone. Seventeen CVA patients recorded intensity and frequency of cough every day. Spirometry and provocative concentration of methacholine causing a 20% fall in forced expiratory volume in 1 second (PC20) were measured in the run-in period and after cough almost completely relieved on therapy. Cough score had improved within 2 weeks after the initiation of bronchodilator therapy. Forced expiratory volume in one second (FEV1) was significantly increased from 2.7 +/-0.7 L in the run-in period to 2.8+/-0.7 L after improvement of cough. However, the geometric mean (GSEM) PC20 value did not change from the run-in period [1542 (GSEM 1.29) microg/mL] to the time of improvement [2600 (GSEM 1.43) microg/mL]. Mildly increased bronchial responsiveness in CVA does not improve when only bronchodilator therapy is carried out. Because bronchial hyperresponsiveness has been shown to be a risk factor for typical asthma onset from CVA, the effect of inhaled corticosteroids on the longitudinal changes in bronchial responsiveness should be examined.

Bronchial asthma showing reduction in FEV1 after inhalation of Qvar.

The administration of Qvar (a hydrofluoroalkane-134a beclomethasone dipropionate; HFA-BDP) is highly useful for the treatment of patients with asthma. However, we found in a case of bronchial asthma that replacing the prior inhaled corticosteroids with Qvar resulted in temporary dyspnea and reduction in forced expiratory volume in 1 second (FEV1). Qvar contains beclomethasone dipropionate combined with absolute ethanol and an alternative to fluorocarbon. The patient had complicated alcohol-induced asthma. FEV1 decreased markedly and immediately after Qvar inhalation. The Qvar placebo is free of beclomethasone but contains other ingredients (ethanol and fluorocarbon). FEV1 did not decrease after the Qvar placebo, Aldecin inhalation, and Qvar inhalation orally treated with atropine before inhalation of Qvar. It seems unlikely that the components of Qvar (except beclomethasone) are responsible for the reduction in FEV1 observed immediately after inhalation of Qvar. These findings would be noteworthy when using Qvar for Japanese patients with asthma known to have a relatively high frequency of the complication of alcohol-induced asthma.

Pulmonary sarcoidosis with usual interstitial pneumonia distributed predominantly in the lower lung fields.

Nodular and reticular opacities were detected in both lower lung fields of a 75-year-old man in 2000. Bronchoscopy revealed pulmonary sarcoidosis. In 2002, nodular and reticular opacities were shown in the right upper lobe, and video-assisted thoracoscopic surgery was performed. The histological findings revealed usual interstitial pneumonia (UIP)-like lesions, whereas non-caseous granulomas were not detected. In the present case of pulmonary sarcoidosis, nodular and reticular opacities were predominantly distributed in both lower lung fields, and the histological findings obtained by video-assisted thoracoscopic surgery showed UIP-like lesions. These findings may enlighten the assist in understanding of the process of development of pulmonary sarcoidosis.

Randomized phase II trial of OK-432 in patients with malignant pleural effusion due to non-small cell lung cancer.

To determine the optimum dose of OK-432 for intrathoracic administration, a multicenter randomized phase II trial was conducted in patients with malignant pleural effusion due to non-small cell lung cancer. Patients with histologically- or cytologically-proven malignant pleural effusions were randomized to arm A (10 Klinische Einheit (KE) of OK-432) or arm B (1 KE of OK-432). OK-432 was injected intrapleurally over 30 min on days 1 and 3 and the chest tube was clamped for 6 h. If control was inadequate on day 8, 10 KE was administered on days 8 and 10 in each treatment arm. Forty patients were enrolled and 38 patients were eligible (19 in arm A and 19 in arm B). The effusion control rate on day 8 was 79% in arm A and 53% in arm B, while control rates on day 28 were 74% and 84%, respectively. The median drainage time after administration was significantly shorter in arm A (4.0 +/- 1.2 days) than in arm B (7.0 +/- 1.7 days). The total drainage volume was also significantly less in arm A than in arm B. No grade 4 toxicities or treatment-related deaths were observed in either treatment arm. Intrathoracic injection of OK-432 is a feasible treatment for malignant pleural effusion. Although the malignant pleural effusion control rate was equivalent in each treatment arm, faster control and less drainage were achieved in arm A. A dose of OK-432 10 KE/body is, therefore, recommended for further trial.

Comparison of cough reflex sensitivity after an inhaled antigen challenge between actively and passively sensitized guinea pigs.

BACKGROUND: Late asthmatic response is observed following antigen challenge in actively, but not passively, sensitized guinea pigs. Although cough reflex sensitivity is increased after antigen challenge in actively sensitized guinea pigs, it is unknown whether the antigen-induced increase in cough reflex sensitivity develops in passively sensitized animals. The aim of this study was to compare the cough reflex sensitivity to inhaled capsaicin after an inhaled antigen challenge between actively and passively sensitized guinea pigs. METHODS: Measurement of number of coughs elicited by increasing concentrations of capsaicin (10(-6) and 10(-4) M) and bronchial responsiveness to ascending concentrations of methacholine, and analysis of bronchoalveolar lavage fluid (BALF) were separately performed 24 h after an antigen challenge in actively and passively sensitized guinea pigs. RESULTS: Percentage of eosinophils in BALF and bronchial responsiveness to methacholine were increased 24 h after the antigen challenge in both actively and passively sensitized animals compared with saline-challenged actively and passively sensitized animals, respectively. Absolute number of eosinophils in BALF from actively sensitized and antigen-challenged guinea pigs was significantly greater than that from passively sensitized and antigen-challenged animals. Cough response to capsaicin and concentration of substance P in BALF were increased 24 h after the antigen challenge in actively sensitized guinea pigs, but not in passively sensitized guinea pigs. Bronchial responsiveness, cough reflex sensitivity and substance P concentration and total cells in BALF were increased in actively sensitized and saline challenged guinea pigs compared with passively sensitized and saline challenged animals. CONCLUSION: The results suggest that active sensitization per se increases cough reflex sensitivity accompanied by increased inflammatory cells and substance P level in BALF, and antigen challenge further increases them, while simple IgE- and/or IgG-mediated allergic reaction per se or the low intensity of eosinophil infiltration in the airway itself may not affect cough reflex sensitivity in guinea pigs.

Phosphodiesterase 3 inhibition and cough in elderly asthmatics.

AIMS: Cough is a common symptom of bronchial asthma, a chronic inflammatory airway disease. Recently, the therapeutic effects of selective phosphodiesterase (PDE) inhibitors have been focused on bronchial asthma. This study was designed to investigate the clinical effect of PDE 3 inhibition on cough reflex sensitivity in elderly patients with bronchial asthma. METHODS: Effects of cilostazol, a PDE 3 inhibitor, on cough response to inhaled capsaicin were examined in 11 patients over 70 years with stable asthma in a randomized, placebo-controlled cross over study. Capsaicin cough threshold, defined as the lowest concentration of capsaicin eliciting five or more coughs, was measured as an index of airway cough reflex sensitivity. RESULTS: The cough threshold was significantly (p < 0.05) increased after two-week treatment with cilostazol (100 mg twice a day orally) compared with placebo [48.8 (GSEM 1.4) vs. 29.2 (GSEM 1.3) muM]. CONCLUSION: These findings indicate that PDE 3 inhibition may be a novel therapeutic option for elderly patients with asthma, especially for their cough symptoms.

Inhaled lysophosphatidylcholine provokes bronchoconstriction in guinea pigs in vivo.

Lysophosphatidylcholine is increased in the airway of bronchial asthma, but its role is not clear. We investigated the role of lysophosphatidylcholine in asthma in anaesthetized, mechanically ventilated guinea pigs. Pressure at the airway opening was measured as an index of bronchial response. Increasing doses of lysophosphatidylcholine (1--10 mg/ml) were inhaled and then bronchoalveolar lavage was carried out. 100 and 200 microg/ml methacholine were inhaled 10 min after inhalation of 2.5 mg/ml lysophosphatidylcholine, 10 mg/ml dipalmitoyl phosphatidylcholine and 10 mg/ml glycerophosphocholine, all of which per se did not change the pressure at the airway opening. Effect of 1.0 microg/kg salbutamol, or 60 mg/kg diphenhydramine on the lysophosphatidylcholine-induced increase in the pressure at the airway opening was investigated. Inhalation of lysophosphatidylcholine dose-dependently increased the pressure at the airway opening and increased bronchial responsiveness to methacholine. On the other hand, inhalation of dipalmitoyl phosphatidylcholine decreased the pressure at the airway opening and decreased bronchial responsiveness to methacholine. Intravenously administered salbutamol, but not diphenhydramine, prevented the lysophosphatidylcholine-induced increase in the pressure at the airway opening. The percentage of leukocytes in bronchoalveolar lavage fluid did not change significantly at least within 20 min after the lysophosphatidylcholine inhalation. Lysophosphatidylcholine causes bronchoconstriction and enhances bronchial responsiveness without inducing leukocyte infiltration in the airway, suggesting that lysophosphatidylcholine may be a new bronchoconstrictor mediator in bronchial asthma.

In vivo PAF-induced airway eosinophil accumulation reduces bronchial responsiveness to inhaled histamine.

Chronic eosinophilic bronchitis and bronchial hyperresponsiveness have been considered to be the fundamental features of bronchial asthma. However, the role of airway eosinophils in bronchial responsiveness in vivo has not been fully discussed. The aim of this study was to investigate the direct effect of airway eosinophil accumulation on bronchial responsiveness in vivo. Guinea pigs were transnasally treated with platelet activating factor (PAF) or vehicle twice a week for a total of 3 weeks. Anesthetized guinea pigs were surgically cannulated and artificially ventilated 48 h after the last administration of PAF or vehicle. Ten minutes after the installation of artificial ventilation, ascending doses of histamine were inhaled. In a subsequent study, selective inhibitors of diamine oxidase and histamine N-methyltransferase were intravenously administered before the histamine inhalation in the PAF-treated animals. Next study was conducted 20 min after treatment with indomethacin in this study line. Finally, ascending doses of methacholine were inhaled in our animal model. Proportion of eosinophils and the number of nuclear segmentation in bronchoalveolar lavage fluid significantly increased in guinea pigs treated with PAF compared with vehicle and this finding was confirmed histologically. Nevertheless, bronchial responsiveness to inhaled histamine, but not methacholine, was significantly decreased by the PAF treatment. This bronchoprotective effect induced by PAF remained following aminoguanidine and histamine N-methyltransferase administration, but abolished by treatment of indomethacin. These results suggest that in vivo airway eosinophils may reduce nonspecific bronchial responsiveness through production of inhibitory or bronchoprotective prostanoids, but not through histaminase production.

[A case of pulmonary sarcoidosis with usual interstitial pneumonia-like lesions distributed predominantly in the lower lung fields].

In 2000, in a 75-year-old man, nodular and reticular opacities were detected in both lower lung fields. He was admitted to our hospital for further examination of these abnormal shadows. Bronchoscopic examination revealed pulmonary sarcoidosis. Prednisolone was prescribed because cardiac sarcoidosis was diagnosed as a clinical complication. In April 2002, the patient visited our hospital for dyspnea on effort. Chest radiography and computed tomography showed nodular and reticular opacities in the right upper lobe, and video-assisted thoracoscopic surgery was performed on the basis of a histological diagnosis. The histological findings of the biopsied specimens revealed a lesion of the type seen in usual interstitial pneumonia, whereas non-caseous granulomas were not detected. His symptoms and chest radiographic findings improved and stabilized with prednisolone and azathioprine. In the present case of pulmonary sarcoidosis, the reticular and nodular opacities predominantly distributed in both lower lung fields, and the histological findings obtained by video-assisted thoracoscopic surgery showed a usual interstitial pneumonia-like lesion. These findings may assist in the understanding of the process of development of pulmonary sarcoidosis.

Th2 cytokine inhibition and cough in asthmatic and bronchitic patients.

BACKGROUND: Activated T helper lymphocytes are present in the airway and their production of cytokines is important in the pathogenesis of asthma, however, the relationship between T helper lymphocyte-derived cytokines and airway cough reflex sensitivity remains unknown. METHODS: The effect of the orally active Th2 cytokine inhibitor suplatast tosilate on cough response to inhaled capsaicin was examined in eleven patients with stable atopic asthma and compared with patients having non-atopic asthma and chronic bronchitis (the latter of which is not related to Th2 cytokines). Capsaicin cough threshold, defined as the lowest concentration of capsaicin eliciting five or more coughs, was measured as an index of airway cough reflex sensitivity. Concentration of serum total IgE level was also measured after treatment with suplatast tosilate. RESULTS: The cough threshold after two weeks treatment with suplatast tosilate was significantly greater than the value with placebo accompanied by decrease of serum IgE level in atopic asthmatics. This significance was not observed in patients with non-atopic asthma or chronic bronchitis. CONCLUSIONS: Th2 cytokines may be possible modulators augmenting airway cough reflex sensitivity in atopic asthmatic airways but not in non-atopic asthmatic or bronchitic airways.

Airway eosinophil accumulation on sensory neuropeptide release in a guinea pig model of distilled-water-induced bronchoconstriction.

BACKGROUND: Increased numbers of eosinophils in the airways is characteristic of asthma. However, it remains unclear whether airway eosinophils enhance or reduce the release of neuropeptides in the airways in vivo. This study was conducted to elucidate the influence of airway eosinophil accumulation on the ultrasonically nebulized distilled water (UNDW)-induced bronchoconstriction in our newly developed animal model, which is mediated by sensory neuropeptides. METHODS: Guinea pigs were transnasally treated with 100 mg/kg of platelet activating factor (PAF), or vehicle, twice a week for 3 weeks. We then conducted three experiments. In the first, UNDW was inhaled 20 min after aerosolized antigen challenge, and bronchoalveolar lavage (BAL) was performed in PAF-treated and passively sensitized animals. In the second, PAF-treated animals were exposed for 20 s to ascending doses of methacholine at intervals of 5 min In the third, passively sensitized animals were administered selective NK1 antagonist, SR 140333, selective NK2 antagonist, SR 48968, or vehicle, intravenously 5 min before UNDW-induced bronchoconstriction. RESULTS: The proportion of eosinophils in BAL fluid was significantly increased in guinea pigs treated with PAF, compared with the vehicle. The PAF treatment did not affect antigen-induced immediate asthmatic response, UNDW-induced bronchoconstriction, or bronchial responsiveness to inhaled methacholine. SR 140333, but not SR 48968, inhibited the UNDW-induced bronchoconstriction. CONCLUSION: We conclude that eosinophils accumulated in the airways, caused by repeated intranasal administration of PAF, does not affect the release of substance P induced by UNDW inhalation, or the action of released substance P in vivo.

Effect of carbocysteine on cough reflex to capsaicin in asthmatic patients.

AIMS: Cough, one of the main symptoms of bronchial asthma, is a chronic airway inflammatory disease with functionally damaged bronchial epithelium. Recently, we established an animal model with cough hypersensitivity after antigen challenge and clearly showed the protective effect of carbocysteine in this model. This study was designed to investigate the clinical effect of carbocysteine for cough sensitivity in patients with bronchial asthma. METHODS: The effects of the two orally active mucoregulatory drugs, carbocysteine and ambroxol hydrochloride, on cough response to inhaled capsaicin were examined in 14 patients with stable asthma. Capsaicin cough threshold, defined as the lowest concentration of capsaicin eliciting five or more coughs, was measured as an index of airway cough sensitivity. RESULTS: Geometric mean values of the cough threshold at run-in (baseline) and after 4 weeks' treatment of placebo, 1500 mg day-1 of carbocysteine and 45 mg day-1 of ambroxol hydrochloride were 12.8 micro M (95% confidence interval [CI] 5.5, 29.6), 11.0 micro M (95% CI 4.4, 27.5), 21.0 micro M (95% CI 8.8, 50.2) and 11.6 micro M (95% CI 5.8, 23.3), respectively. The cough threshold for carbocysteine was significantly greater than those of ambroxol hydrochloride (P = 0.047) and placebo (P = 0.047), respectively. CONCLUSIONS: These findings indicate that carbocysteine administration may be a novel therapeutic option for asthmatic patients, especially with cough variant asthma.

Thromboxane antagonism and cough in chronic bronchitis.

BACKGROUND: The increased eicosanoid synthesis has been suggested as the underlying mechanism of chronic productive cough in patients with chronic bronchitis. METHOD: The effects of the orally active thromboxane A2 (TxA2) receptor antagonist seratrodast and the cysteinyl leukotrienes (cLTs) receptor antagonist pranlukast on cough response to inhaled capsaicin were examined in sixteen patients with stable chronic bronchitis. Capsaicin cough threshold, defined as the lowest concentration of capsaicin eliciting five or more coughs, was measured as an index of airway cough sensitivity. RESULTS: The cough threshold was significantly increased compared with placebo after four-week treatment with seratrodast, but not after treatment with pranlukast. CONCLUSIONS: TxA2, but not cLTs, may be a possible modulator augmenting airway cough sensitivity in chronic bronchitis. Thromboxane antagonism may be considered to be one of the therapeutic options for the treatment of chronic productive cough.

Lack of adrenomedullin on antigen-induced bronchoconstriction in guinea pigs in vivo.

Antigen challenge can provoke acute bronchoconstriction, recognized as immediate asthmatic response (IAR), but the evolving events in this reaction are not well defined. Recently, a novel peptide, designated adrenomedullin, was isolated from human pheochromocytoma, and has been shown to have potent systemic and pulmonary vasodilator activity.The purpose of this study was to elucidate the influence of adrenomedullin in the development of IAR. Passively sensitized guinea pigs were anesthetized and treated with diphenhydramine hydrochloride, and then artificially ventilated. Ovalbumin was inhaled after an intravenous administration of adrenomedullin. Other studies were performed in naive guinea pigs to investigate the airway responses to inhaled methacholine or histamine after an intravenous administration of adrenomedullin. Antigen challenge caused bronchoconstriction in sensitized guinea pigs. Adrenomedullin did not inhibit the antigen-induced bronchoconstriction in sensitized guinea pigs or the dose-dependent responses to inhaled methacholine or histamine in naive animals in spite of its vasodilating effect. We conclude that an intravenous administration of adrenomedullin does not influence antigen-induced bronchoconstriction or bronchial responsiveness to inhaled methacholine or histamine in vivo.

Alpha(1L)-, but not alpha(1H)-, adrenoceptor antagonist prevents allergic bronchoconstriction in guinea pigs in vivo.

alpha-Adrenoceptors have been classified into alpha(1)- and alpha(2)-adrenoceptors. Recently, the alpha(1)-adrenoceptors were divided into two subtypes: alpha(1L) with low affinity and alpha(1H) with high affinity for prazosin. Little is known concerning the role of each subtype of alpha(1)-adrenoceptor in asthma. We investigated the effects of specific antagonists of alpha(1)- and alpha(2)-, alpha(1H)-, alpha(1L)-, and alpha(2)-adrenoceptors, namely moxisylyte, prazosin, 3-[N-[2-(4-hydroxy-2-isopropyl-5-methylphenoxy) ethyl]-N-methylaminomethyl]-4-methoxy-2, 5, 6-trimethylphenol hemifumarate (JTH-601), and yohimbine, respectively, on antigen-induced airway reactions in guinea pigs. Fifteen minutes after intravenous administration of moxisylyte (0.01, 0.1 or 1 mg/kg), prazosin (0.01, 0.1, 1 or 10 mg/kg), JTH-601 (1, 3, 6 or 10 mg/kg) or yohimbine (0.1 or 1 mg/kg), passively sensitized and artificially ventilated animals received an aerosolized antigen challenge. Bronchial responsiveness to inhaled methacholine was assessed as the dose of methacholine required to produce a 200% increase in the pressure at the airway opening (PC(200)) in non-sensitized animals. JTH-601 and moxisylyte, but not prazosin or yohimbine, dose dependently inhibited antigen-induced bronchoconstriction. None of the tested drugs altered PC(200). JTH-601 significantly reduced leukotriene C(4) levels in bronchoalveolar lavage fluid obtained 5 min after antigen challenge, but prazosin did not. These results indicate that prevention of antigen-induced bronchoconstriction by blockade of alpha-adrenoceptors is due to the inhibition of mediator release via alpha(1L)-adrenoceptor antagonism.