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Attenuation of antigen-induced bronchoconstriction in guinea pigs by a new xanthine derivative (HWA448).

We examined the effect of a new xanthine derivative, HWA448, on antigen-induced bronchoconstriction in actively sensitized guinea pigs. Guinea pigs were sensitized by intraperitoneal injection of bovine serum albumin (BSA) on two occasions, separated by 10 days. Two weeks after the second injection, the animal was placed in a two-chambered whole body plethysmograph and specific airway resistance (SRaw) was monitored for 10 min after an aerosol inhalation of BSA. HWA448 prevented the increase in SRaw after challenge (at 5 and 20 mg/kg i.p.). Aminophylline also prevented the increase in SRaw at 20 mg/kg, but not at a 5-mg/kg dose. The concentration of HWA448, which produced 50% relaxation of the tracheal rings constricted with 0.1 mM of histamine, was 49.9 microM as compared with 18.2 microM in aminophylline. HWA448 has a protective effect on antigen-induced bronchoconstriction in guinea pigs and may be a useful agent in the therapy of bronchial asthma.

Aminophylline↗

Inhibition of IgE-mediated leukotriene generation and bronchoconstriction in primates with a new 5-lipoxygenase inhibitor, E6080.

The inhibitory effects of a novel compound, 6-hydroxy-2-(4-sulfamoylbenzylamino)-4,5,7-trimethylbenzothiazo le hydrochloride (E6080) on IgE-mediated reactions in vitro and in vivo were determined in rhesus monkeys. E6080 inhibited both antigen- and anti-human IgE-induced leukotriene C4 generations from lung fragments at similar concentrations: the IC50s of E6080 were 1.11 and 0.96 microM, respectively. AA861 also inhibited both leukotriene C4 generations with IC50s of 0.79 and 0.76 microM, respectively. All 9 monkeys demonstrating positive cutaneous reactivity against Ascaris antigen at < 10(-7) g protein/0.1 ml showed reproducible bronchoconstriction upon aerosolized antigen challenge, but 5 monkeys demonstrating weak or no reactivity to the antigen at levels > 10(-5) g protein/0.1 ml showed no significant bronchoconstriction. The high responder monkeys showed a marked increase in lung resistance (RL 335.3 +/- 85.3%, n = 11) and a decrease in dynamic lung compliance (67.7 +/- 4.2%, n = 11) after antigen challenge following pretreatment with diphenhydramine. These pulmonary changes lasted for more than 30 min. E6080 at oral doses of 3 and 10 mg/kg showed dose-dependent inhibition of both pulmonary changes. Ten milligrams per kilogram of E6080, administered 1.5 h prior to antigen challenge, significantly inhibited the changes in both parameters, while 3 mg/kg showed significant inhibition of only the RL change. These results demonstrate that E6080 inhibited immunologically stimulated leukotriene production in the lung, resulting in inhibition of the antigen-induced airway response in primates.

Animals↗

Late phase bronchoconstriction and eosinophilia as well as methacholine hyperresponsiveness in Ascaris-sensitive rhesus monkeys were reversed by oral administration of U-83836E.

We used the Ascaris-sensitive primate model to assess the effect of oral doses of the 2-aminochroman (U-83836E) lazaroid on the antigen-induced late phase (24 h) bronchoconstriction (LPBC), eosinophilia and methacholine hyperreactivity. Following establishment of consistent lung resistance measurements and bronchoalveolar lavage eosinophilia in 4 Ascaris reactor primates, we determined the baseline aerosol mecholyl provocative challenge for 50% increase (PC50 in mg/ml) in these animals. Twenty-four hours following antigen challenge, we again determined the PC50 (mg/ml). In all 4 animals, there was a statistically significant decrease in PC50 (5.4- to 32-fold, n = 5-7; p < 0.029). Bronchoconstriction at 24 h increased in all 4 (49-86% over saline aerosol, p < 0.05). Eosinophilia increased from 21 to an average of 33% of total cells (p < 0.05 compared to saline). Repeating the antigen challenge in the presence of oral doses of 10 mg/kg U-83836E 18 and 3 h before and 6 h after challenge resulted in 53-70% inhibition of LPBC, 53-81% inhibition of eosinophilia (p < 0.05 compared to Ascaris) and return of the mecholyl PC50 (mg/ml) to before antigen levels (p = NS) thus blocking increased hyperreactivity. These results indicate U-83836E, like steroids, would be an effective drug for asthma and lung inflammation.

Animals↗

Mechanisms of bronchoconstriction after allergen ingestion in sensitized guinea pigs.

We examined whether oral administration of allergen induced bronchoconstriction in sensitized guinea pigs and investigated the mechanisms of bronchoconstriction. The animals had been immunized intraperitoneally with a mixture of Ascaris suum extract and silica gel, and exposed to ozone. They were then challenged with an oral dose of A. suum extract (6 mg/kg), and respiratory resistance (Rrs) was measured up to 7 h. After oral administration of the allergen, an increase in Rrs was observed. The mean values at 1, 3, 5 and 7 h after oral allergen challenge were 150 +/- 21, 149 +/- 11, 151 +/- 12 and 134 +/- 10% of the baseline value, respectively. When saline instead of the allergen was orally administered, almost no significant increase in Rrs was observed up to 7 h. Moreover, in nonsensitized guinea pigs, oral administration of allergen produced no significant increase in Rrs for up to 7 h. When atropine was administered as an aerosol, the increase in Rrs induced by an oral allergen challenge was attenuated. Three of the five atropine-treated guinea pigs showed temporary increases in Rrs immediately after the oral allergen challenge. The mean values of Rrs in the atropine-treated animals challenged with oral allergen at 1, 3, 5 and 7 h were 106 +/- 3, 106 +/- 5, 115 +/- 5 and 102 +/- 4% of baseline value, respectively. In the animals which received oral allergen, the number of neutrophils in bronchoalveolar lavage fluid (BALF) significantly increased 2.0-fold (p < 0.05), while no significant increase in the number of eosinophils, macrophages, or lymphocytes in BALF was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗

Inhaled formoterol in the prevention of exercise-induced bronchoconstriction in asthmatic children.

The duration and magnitude of the effect of inhaled formoterol (12 micrograms) against exercise-induced bronchoconstriction (EIB) was compared with that of inhaled salbutamol (200 micrograms) and that of placebo in 15 children with asthma and EIB in a double-blind, double-dummy, within-patient, placebo-controlled study. The treatments were given by metered dose aerosol on three different days. The exercise test was performed at the 3rd and the 12th hour after dosing. The magnitude of the blocking effect was assessed both by evaluating the lowest FEV1 reading obtained within an hour after each exercise test and by considering the percent decrease below the baseline FEV1 measured before drug administration. Comparison of the lowest values obtained during the hour after each exercise test shows that formoterol was significantly better than both salbutamol (p = 0.022), and placebo (p = 0.001) in limiting exercise-induced bronchoconstriction after the first exercise test (3 h after dosing), while no difference was observed between salbutamol and placebo (p = 0.198). After the second exercise test (12 h after dosing), formoterol again proved to be more effective than both salbutamol (p = 0.008) and placebo (p = 0.001), and no significant difference was observed between salbutamol and placebo (p = 0.391). The evaluation of the mean percentage decrease in FEV1 confirmed the results in favor of formoterol in both the exercise tests. No adverse effects were reported in any treatment group. The protection against EIB is significantly more prolonged after formoterol than after salbutamol, and persists for 12 h after dosing.

Administration, Inhalation↗

Changes in residual volume during induced bronchoconstriction in healthy and asthmatic subjects.

The increase of residual volume (RV) was investigated during acute bronchoconstriction induced in healthy subjects by methacholine (MCh) (Group 1, n = 13) and in asthmatics by MCh (Group 2, n = 21), or housemite dust (Group 3, n = 11) during early and late airway responses (EAR and LAR), or a series of deep breaths (Group 4, n = 7). In all subjects the difference between residual volume after partial (RVp) and maximal maneuver (RV), expressed as a percentage of control FVC, increased during bronchoconstriction and was correlated with the percent increase of maximal to partial flow ratio at 50% of control FVC (M/P50) (r = 0.854, p < 0.0001). At comparable reduction of partial expiratory flow at 50% of control FVC (VP50), the decreases of FEV1 and FVC were less in healthy than asthmatic subjects, whereas the change of FEV1/FVC was similar in all groups, reflecting similar change in slope of flow-volume curves. The increase of RVp was similar in all groups (range: 15 to 19%), but the increase of RV was 6 +/- 1% (SEM) in healthy subjects and significantly greater (range: 11.1 to 13.3%) in all groups of asthmatics (p < 0.02, analysis of variance [ANOVA]). The effect of deep inhalation (DI) on the airway caliber as assessed by the increase of M/P50 was higher in normal subjects than in all groups of asthmatics (p < 0.0001). A negative correlation was found between the increases of RV and M/P50 in all groups (r = -0.358, p < 0.01), suggesting that healthy subjects had a limited increase of RV because of a marked bronchodilator effect of DI.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Attenuation of aspirin-induced bronchoconstriction by sodium cromoglycate and nedocromil sodium.

The protective activity of nedocromil sodium and of sodium cromoglycate against aspirin-induced asthma has never been investigated in controlled studies. Because it has been reported that aspirin-induced platelet-mediated cytotoxic activity in vitro is inhibited after treatment in vivo with nedocromil but not with cromoglycate, we investigated whether these compounds also exhibit a different protective activity against aspirin-induced bronchoconstriction. Ten patients with aspirin-induced asthma underwent three bronchial challenges with a single dose of lysine acetylsalicylate (LASA) that caused a decrease in FEV1 of 25% or more in a preliminary dose-response test 30 min after inhalation of 4 mg nedocromil sodium, 10 mg sodium cromoglycate, or placebo. FEV1 and SRaw were recorded at intervals for 195 min. After placebo, LASA caused a maximal decrease in FEV1 of 42 +/- 4% of baseline. After cromoglycate and nedocromil the maximal decrease in FEV1 was reduced to 20 +/- 3% and 18 +/- 4%, respectively (p < 0.01 versus placebo for both treatments), without significant differences between the two treatments. Similar results were observed with SRaw. We conclude that, at the recommended therapeutic doses, sodium cromoglycate and nedocromil sodium are equally effective in attenuating aspirin-induced bronchoconstriction and that it is unlikely that platelet activation participates in the pathogenesis of aspirin-induced asthma.

Anti-Asthmatic Agents↗

Effect of leukotriene and thromboxane antagonist on propranolol-induced bronchoconstriction.

beta-adrenoreceptor blockers such as propranolol provoke bronchoconstriction only in asthmatic patients. Although cysteinyl leukotrienes (cLTs) and thromboxane A2 (TXA2) have been proposed to be involved in the pathophysiology of asthma, the role of these lipid mediators in propranolol-induced bronchoconstriction (PIB) has not been evaluated in asthmatics. This study was conducted to elucidate it. Nine patients with stable asthma, in whom a 20% or more decrease in FEV(1) occurred by inhalation of 20 mg/ml or less propranolol, participated in this study. A cLT antagonist, pranlukast (225 mg twice a day), a TXA2 antagonist, seratrodast (80 mg once a day), and placebo were orally given for 2 wk in a randomized and double-blinded manner. The provocative concentration of propranolol causing a 20% fall in FEV(1) (PC(20)) was determined on the last day of each 2-wk treatment. Pranlukast, but not seratrodast, tented to increase FEV(1) compared with placebo (2.14 +/- 0.29 versus 1.99 +/- 0.34 L, p = 0.0543). Pranlukast or seratrodast did not affect the PC(20) in comparison with placebo. We conclude that cLTs or TXA2 are not involved in PIB of asthmatics.

Adrenergic beta-Antagonists↗

Quality of dyspnea in bronchoconstriction differs from external resistive loads.

To test the hypothesis that patients perceive the same quality of dyspnea during mild bronchoconstriction and external resistive loads, we studied subjects with asthma under two conditions: (1) during methacholine bronchoprovocation to mimic the bronchospasm of mild asthma and (2) while breathing on a circuit to which was added a range of external resistors to mimic the mechanical load of mild asthma. During each of these stimuli, respiratory variables, overall dyspnea intensity on a modified Borg scale, and the qualitative descriptors of breathlessness from a 19-item questionnaire were assessed. The "chest tightness" and "constriction" responses were significantly more frequent in the methacholine trials as compared with the external load trials (p < 0.0001). The "chest tightness" or "constriction" response was chosen during 92% of the 26 trials of methacholine bronchoconstriction compared with 3% of the 72 trials of breathing against the external resistors. Changes in functional residual capacity were not significantly different between the two conditions. We conclude that in mild asthma, the sensation of chest tightness is distinct from the sensation of work and effort and is not attributable to the mechanical load imposed on the respiratory system.

Adult↗

Inhalation of an alkaline aerosol by subjects with mild asthma does not result in bronchoconstriction.

Although it is recognized that inhalation of acid aerosols by subjects with asthma can cause bronchoconstriction, the effects of the inhalation of an alkaline aerosol are unknown. When supplemental inflatable restraints (automobile air bags) are deployed an alkaline aerosol is released. This aerosol is composed of particles of sodium carbonate and sodium bicarbonate with some sodium hydroxide. The mass median aerodynamic diameter (MMAD) of the aerosol is approximately 1 micron, and the pH of the aerosol is 9.8 to 10.3. A group of 14 volunteer male subjects with mild asthma inhaled increasing concentrations of this aerosol for 20-min periods of mouth-only tidal ventilation. Pulmonary function tests were performed at baseline (preexposure), after inhalation of room air alone (control), and after each period of inhalation of the aerosol. A total of 5 subjects inhaled aerosols at nominal concentrations of 10, 20, and 40 mg/m3, whereas 11 subjects inhaled aerosols concentrations of approximately 30, 60, and 120 mg/m3. The mean changes in FEV1 and specific airways resistance (SRaw) for the 11 subjects who inhaled the higher concentrations (average highest concentration 126.6 +/- 7.5 mg/m3, mean +/- SEM) were -1.4 +/- 1.9 and +17.5 +/- 8.5%, respectively. Neither change in lung function was clinically or statistically significant. We conclude that the inhalation of relatively high concentrations of this alkaline aerosol by subjects with mild asthma does not result in bronchoconstriction.

Adolescent↗

Prolonged protection against methacholine-induced bronchoconstriction by the inhaled beta 2-agonist formoterol.

Formoterol fumarate is a new, high-affinity, beta 2-adrenergic receptor agonist that causes bronchodilation for at least 12 h. The purpose of this study was to compare the magnitude and duration of the effect of inhalation of formoterol (12 and 24 micrograms), albuterol (200 micrograms), and placebo in terms of protection against methacholine-induced bronchoconstriction. The 16 stable adult asthmatic subjects were studied on four separate study days. On each study day the subjects inhaled 2 puffs of the study medication, and methacholine tests were performed at 30 min and 4, 8, and 12 h later. Results were expressed as the provocative concentration of methacholine required to cause a 20% fall in FEV1 (PC20). At 30 min, 12 and 24 micrograms formoterol caused a mean 14- to 20-fold decrease in responsiveness, and albuterol a 12-fold decrease. However, albuterol had no significant protective effect at 4 h or thereafter, whereas there was still an 8-fold decrease in responsiveness for 24 micrograms formoterol and a 6-fold decrease for 12 micrograms formoterol at 12 h. This study has shown that both doses of formoterol were still actively protective against induced bronchoconstriction 12 h after inhalation, with minimal side effects. This suggests that formoterol may prove to be a very useful bronchodilator for the treatment of patients with asthma who have significant airway hyperresponsiveness or nocturnal symptoms and who require inhaled beta 2-agonists at least twice daily.

Administration, Inhalation↗

Transient airway cooling modulates dry-air-induced and hypertonic aerosol-induced bronchoconstriction.

Airflow-induced bronchoconstriction (AIB) may be initiated in asthmatic patients by inhaling dry air during eucapnic hyperventilation or exercise. Hypertonic aerosol-induced bronchoconstriction (HIB) also occurs in these patients, but it differs from AIB by exhibiting a faster time course. Although AIB and HIB probably increase airway fluid osmolality, only AIB is associated with airway cooling. In light of the similarities between our canine model and human AIB, we examined peripheral airway responses to dry air and hypertonic aerosol challenge. Specifically, we studied the magnitude and time course of these responses in an in situ, isolated, perfused lobe in which airway temperature was independently controlled. At body temperature, HIB peaked immediately after challenge, whereas transient airway cooling during aerosol challenge delayed HIB. In contrast, airway cooling attenuated AIB but did not alter its time course. Hypocapnia- and histamine-induced responses were not affected by airway cooling, suggesting that smooth muscle function was not impaired. To the extent that the mechanisms producing AIB in dogs and in humans are similar, our results suggest that (1) changes in airway fluid osmolality initiate AIB, (2) AIB = HIB + Cooling, and (3) exercise-induced asthma results from an imbalance between an excitatory pathway stimulated by airway drying and an inhibitory pathway initiated by airway cooling.

Aerosols↗

Time course and calcium dependence of sustained bronchoconstriction induced by deep inhalation in asthma.

We studied six asthmatic patients who showed a progressive decrease in FEV1 when successive forced expiratory maneuvers were performed at 1-min intervals. We determined the time course of changes in specific airway conductance following a single deep inhalation (DI) and the ratio of maximum expiratory flow at 40% of FVC from maximal and partial flow-volume curves (MEF40M/P) during a series of forced expiratory maneuvers. Specific airway conductance measured 3 s after DI was increased by 11 +/- 6 (SE)%, which was not significantly different from an increase of 23 +/- 8% observed in six healthy control subjects. Later (i.e., 10 to 40 s after DI) specific airway conductance was significantly less than the pre-DI value in asthmatic but not in healthy subjects. Mean FEV1 decreased significantly by 28% from the first to the eighth forced expiratory maneuver performed during a period of 15 min, whereas MEF40M/P was not significantly changed and remained always significantly greater than 1. The voltage-dependent calcium channel antagonist nifedipine significantly prevented the reduction of FEV1 without affecting MEF40M/P. We conclude that, in some asthmatic individuals, DI may induce a transient bronchodilatation followed by a calcium-dependent sustained bronchoconstriction. We suggest that the initial bronchodilatation is due to the mechanical interdependence between airways and lung parenchyma, whereas the sustained bronchoconstriction is due to contraction of the airway smooth muscle.

Adult↗

Paradoxical bronchoconstriction with nebulized albuterol but not with terbutaline.

A 40-yr-old woman with severe chronic asthma complained that her regular nebulized albuterol was exacerbating her symptoms. Changing to regular nebulized terbutaline resulted in a marked improvement in her peak flow readings. Double-blind challenge with nebulized albuterol and terbutaline confirmed paradoxical bronchoconstriction with albuterol but not with terbutaline. This indicates that paradoxical bronchoconstriction to beta 2-agonists can be specific to the drug preparation used rather than a class effect, as has previously been suggested.

Adult↗

Effect of Hoe 140 on bradykinin-induced bronchoconstriction in anesthetized guinea pigs.

We have investigated the efficacy of the novel, highly potent, and stable B2 bradykinin (BK) antagonist Hoe 140 against BK-induced bronchoconstriction in guinea pigs via whole body plethysmography and compared different routes of administration. Our results clearly demonstrate that Hoe 140 is highly potent at inhibiting bronchoconstriction induced by either intravenous (i.v.) or inhaled BK. Intravenous BK was strongly inhibited by i.v. Hoe 140 (ID50 13.4 pmol/kg), and less by aerosolized Hoe 140 (ID50 1.34 nmol/kg). Aerosolized BK (235 nmol/kg) was strongly inhibited by 0.1 nmol/kg of aerosolized Hoe 140 given 30 min before. Hoe 140 is the first BK antagonist to effectively inhibit the bronchoconstrictor effect of aerosolized BK. The equieffective i.v. dose of Hoe 140, however, as about 100-fold higher. From the discrepancy in efficacy of Hoe 140 against i.v. and aerosolized BK, it was concluded that i.v. BK has no direct effect on the lung, in contrast to inhaled BK. Moreover, the high potency of Hoe 140 in the guinea pig lung does not confirm the hypothesis of a B3 BK receptor. Based on its high potency and good tolerability, Hoe 140 is appropriate to evaluate the role of BK in human airway diseases.

Aerosols↗

Lack of tolerance to the protective effect of montelukast in exercise-induced bronchoconstriction in children.

The effect over time of regular treatment with montelukast (MNT) in inhibiting exercise-induced bronchoconstriction (EIB) has never been evaluated in children. The aim of the present study was to examine the preventive effect of MNT against EIB in children at different time-points over a 4-week treatment period. Thirty-two asthmatic children (aged 6-12 yrs) were enrolled in a double-blinded, randomised, parallel group design to receive a 4-week treatment with MNT (5 mg chewable tablets administered once daily in the evening) or placebo. Exercise challenge was performed at baseline and after 3, 7 and 28 days of treatment, 20-24 h after dosing. MNT was significantly more protective than placebo against EIB at each time. The mean percentage drop of forced expiratory volume in one second (FEV1) was 24.6, 13.6, 12.0 and 11.6 for MNT, and 24.4, 22.4, 21.8 and 21.0 for placebo, at baseline and after 3, 7 and 28 days, respectively. For each drug, no significant difference in the percentage drop of FEV1 was found between different days. Regular treatment with montelukast provided significant protection against exercise-induced bronchoconstriction in asthmatic children over a 4-week period with no tolerance to the bronchoprotective effect.

Acetates↗

Effects of inhaled nitric oxide on methacholine-induced bronchoconstriction: a concentration response study in rabbits.

Inhaled nitric oxide (NO), at a concentration of 80 ppm, counters the increase in respiratory resistance (Rrs) induced by methacholine, but fails to prevent a reduction in lung compliance (Crs) in a rabbit model. This study reports the effects of 3, 30 and 300 ppm of inhaled NO. New Zealand White rabbits were intubated and mechanically ventilated with 30% oxygen during neurolept anaesthesia. Methacholine (3 mg.ml-1) was nebulized, with or without NO inhalation. Inhalation of 3 and 30 ppm NO had no effect on the induced bronchoconstriction, whereas 300 ppm fully blocked the increase in Rrs. The decrease in Crs due to methacholine was not countered by 3, 30 or 300 ppm NO. On the contrary, inhalation of 300 ppm NO in itself decreased Crs from 5.0 +/- 0.1 to 4.3 +/- 0.1 ml.cmH2O-1. Also, mean arterial pressure (60 +/- 7 to 54 +/- 5 mmHg), alveolar-arterial oxygen tension gradient (0.8 +/- 0.8 to 2.3 +/- 1.8 kPa) and methaemoglobin (0.5 +/- 0.2 to 1.5 +/- 0.5%) changed significantly on inhalation of NO 300 ppm prior to methacholine challenge. We conclude that 3 and 30 ppm NO inhalation does not alter methacholine-induced bronchoconstriction. Inhalation of 300 ppm NO blocks an increase in resistance but fails to counter the reduction in compliance due to methacholine. This suggests that the bronchodilating effects of NO in rabbits in vitro are confined to the large airways.

Administration, Inhalation↗

Dry air- and hypertonic aerosol-induced bronchoconstriction and cellular responses in the canine lung periphery.

Dry air and hypertonic saline both create an osmotic stress to the airways, whilst dry air alone induces transient cooling of the airway mucosa. It is unclear whether these two stimuli lead to bronchoconstriction via the same mechanisms. We compared airflow- and hypertonic aerosol-induced bronchoconstriction (AIB and HIB, respectively) in the canine lung periphery, using a wedged bronchoscope to measure collateral system resistance (Rcs). Bronchoalveolar lavage (BAL) was used to examine changes in cells and mediators during AIB and HIB. We found that: 1) peripheral airways are not refractory to either dry air or hypertonic aerosols, and do not exhibit cross-refractoriness to these stimuli; 2) differences in strength of stimulus can alter the magnitude but not the time course of HIB; 3) within an individual, AIB and HIB are significantly correlated; 4) epithelial cells recovered in BAL fluid (BALF) are significantly elevated after AIB, and are similarly increased after HIB; 5) when compared to control, mediators recovered in BALF are significantly elevated after AIB but not HIB; 6) HIB is not altered by cyclo-oxygenase inhibition; and 7) lavage with hypertonic fluid does not affect the number of epithelial cells recovered, although the concentrations of some mediators are increased. We speculate that differences in cell and mediator profiles reflect differences in the time course of AIB and HIB that result from the modulation of temperature sensitive pathways that occurs during dry air, but not during hypertonic aerosol challenge.

Aerosols↗