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American Journal of Physiology. Lung... Oct 2022The enzyme, nitric oxide-sensitive guanylyl cyclase (NO-GC), is activated by binding NO to its prosthetic heme group and catalyzes the formation of cGMP. The NO-GC is...
The enzyme, nitric oxide-sensitive guanylyl cyclase (NO-GC), is activated by binding NO to its prosthetic heme group and catalyzes the formation of cGMP. The NO-GC is primarily known to mediate vascular smooth muscle relaxation in the lung, and inhaled NO has been successfully used as a selective pulmonary vasodilator. In comparison, NO-GC's impact on the regulation of airway tone is less acknowledged and, most importantly, little is known about the issue that NO-GC signaling is accomplished by two isoforms: NO-GC1 and NO-GC2, implying the existence of distinct "cGMP pools." Herein, we investigated the functional role of the NO-GC isoforms in respiration by measuring lung function parameters of isoform-specific knockout (KO) mice using noninvasive and invasive techniques. Our data revealed the participation and ongoing influence of NO-GC1-derived cGMP in the regulation of airway tone by showing that respiratory resistance was enhanced in NO-GC1-KOs and increased more pronouncedly after the challenge with the bronchoconstrictor methacholine. The tissue resistance and stiffness of NO-GC1-KOs were also higher because of narrowed airways that cause tissue distortion. Contrariwise, NO-GC2-KOs displayed reduced tissue elasticity, elastic recoil, and airway reactivity to methacholine, which did not even increase in an ovalbumin model of asthma that induced hyperresponsiveness in NO-GC1-KOs. In addition, conscious NO-GC2-KOs showed a higher breathing rate with a shorter duration of inspiration and expiration time, which remained faster even in the presence of bronchoconstrictors that slow down breathing. Thus, we provide evidence of two distinct NO/cGMP pathways in airways, accomplished by either NO-GC1 or NO-GC2, adjusting differentially the airway reactivity.
Topics: Animals; Bronchoconstrictor Agents; Cyclic GMP; Guanylate Cyclase; Heme; Methacholine Chloride; Mice; Mice, Knockout; Nitric Oxide; Ovalbumin; Protein Isoforms; Soluble Guanylyl Cyclase; Vasodilator Agents
PubMed: 35972838
DOI: 10.1152/ajplung.00404.2021 -
Biosensors & Bioelectronics Oct 2021The methacholine challenge test is considered to be the gold standard bronchoprovocation test used to diagnose asthma, and this test is always performed in pulmonary...
The methacholine challenge test is considered to be the gold standard bronchoprovocation test used to diagnose asthma, and this test is always performed in pulmonary function labs or doctors' offices. Methacholine (MCH) acts by inducing airway tightening/bronchoconstriction, and more importantly, MCH is hydrolyzed by cholinesterase enzyme (ChE). Recently, the American Thoracic Society raised concerns about pulmonary function testing during the COVID-19 pandemic due to recently reported correlation between cholinesterase and COVID-19 pneumonia severity/mortality, and it was shown that cholinesterase levels are reduced in the acute phase of severe COVID-19 pneumonia. This work describes the microfabrication of potentiometric sensors using copper as the substrate and chemically polymerized graphene nanocomposites as the transducing layer for tracking the kinetics of MCH enzymatic degradation in real blood samples. The in-vitro estimation of the characteristic parameters of the MCH metabolism [Michaelis-Menten constant (K) and reaction velocity (V)] were found to be 241.041 μM and 56.8 μM/min, respectively. The proposed sensor is designed to be used as a companion diagnostic device that can (i) answer questions about patient eligibility to perform methacholine challenge tests, (ii) individualize/personalize medical dosing of methacholine, (iii) provide portable and inexpensive devices allowing automated readouts without the need for operator intervention (iv) recommend therapeutic interventions including intensive care during early stages and reflecting the disease state of COVID-19 pneumonia. We hope that this methacholine electrochemical sensor will help in assaying ChE activity in a "timely" manner and predict the severity and prognosis of COVID-19 to improve treatment outcomes and decrease mortality.
Topics: Biosensing Techniques; Bronchoconstrictor Agents; COVID-19; Humans; Methacholine Chloride; Pandemics; SARS-CoV-2
PubMed: 34166943
DOI: 10.1016/j.bios.2021.113439 -
Allergy Jul 2021Airway hyperresponsiveness (AHR) is a feature of asthma in which airways are hyperreactive to stimuli causing extensive airway narrowing. Methacholine provocations...
BACKGROUND
Airway hyperresponsiveness (AHR) is a feature of asthma in which airways are hyperreactive to stimuli causing extensive airway narrowing. Methacholine provocations assess AHR in asthma patients mainly by direct stimulation of smooth muscle cells. Using in vivo mouse models, mast cells have been implicated in AHR, but the mechanism behind has remained unknown.
METHODS
Cpa3 mice, which lack mast cells, were used to assess the role of mast cells in house dust mite (HDM)-induced experimental asthma. Effects of methacholine in presence or absence of ketanserin were assessed on lung function and in lung mast cells in vitro. Airway inflammation, mast cell accumulation and activation, smooth muscle proliferation, and HDM-induced bronchoconstriction were evaluated.
RESULTS
Repeated intranasal HDM sensitization induced allergic airway inflammation associated with accumulation and activation of lung mast cells. Lack of mast cells, absence of activating Fc-receptors, or antagonizing serotonin (5-HT) receptors abolished HDM-induced trachea contractions. HDM-sensitized mice lacking mast cells had diminished lung-associated 5-HT levels, reduced AHR and methacholine-induced airway contraction, while blocking 5-HT receptors in wild types eliminated AHR, implying that mast cells contribute to AHR by releasing 5-HT. Primary mouse and human lung mast cells express muscarinic M3 receptors. Mouse lung mast cells store 5-HT intracellularly, and methacholine induces release of 5-HT from lung-derived mouse mast cells and Ca flux in human LAD-2 mast cells.
CONCLUSIONS
Methacholine activates mast cells to release 5-HT, which by acting on 5-HT receptors enhances bronchoconstriction and AHR. Thus, M3-directed asthma treatments like tiotropium may also act by targeting mast cells.
Topics: Animals; Asthma; Disease Models, Animal; Humans; Lung; Mast Cells; Methacholine Chloride; Mice; Mice, Inbred BALB C; Pyroglyphidae; Serotonin
PubMed: 33486786
DOI: 10.1111/all.14748 -
Toxicology and Applied Pharmacology Sep 2022Workers involved in oil exploration and production in the upstream petroleum industry are exposed to crude oil vapor (COV). COV levels in the proximity of workers during...
Workers involved in oil exploration and production in the upstream petroleum industry are exposed to crude oil vapor (COV). COV levels in the proximity of workers during production tank gauging and opening of thief hatches can exceed regulatory standards, and several deaths have occurred after opening thief hatches. There is a paucity of information regarding the effects of COV inhalation in the lung. To address these knowledge gaps, the present hazard identification study was undertaken to investigate the effects of an acute, single inhalation exposure (6 h) or a 28 d sub-chronic exposure (6 h/d × 4 d/wk × 4 wks) to COV (300 ppm; Macondo well surrogate oil) on ventilatory and non-ventilatory functions of the lung in a rat model 1 and 28 d after acute exposure, and 1, 28 and 90 d following sub-chronic exposure. Basal airway resistance was increased 90 d post-sub-chronic exposure, but reactivity to methacholine (MCh) was unaffected. In the isolated, perfused trachea preparation the inhibitory effect of the airway epithelium on reactivity to MCh was increased at 90 d post-exposure. Efferent cholinergic nerve activity regulating airway smooth muscle was unaffected by COV exposure. Acute exposure did not affect basal airway epithelial ion transport, but 28 d after sub-chronic exposure alterations in active (Na and Cl¯) and passive ion transport occurred. COV treatment did not affect lung vascular permeability. The findings indicate that acute and sub-chronic COV inhalation does not appreciably affect ventilatory properties of the rat, but transient changes in airway epithelium occur.
Topics: Airway Resistance; Animals; Inhalation Exposure; Lung; Methacholine Chloride; Petroleum; Rats
PubMed: 35798068
DOI: 10.1016/j.taap.2022.116154 -
Respiratory Research Aug 2017Methacholine dose-response curves illustrate pharmacologic bronchoprotection against methacholine-induced airway hyperresponsiveness and can be used to quantitate... (Comparative Study)
Comparative Study Randomized Controlled Trial
The effect of glycopyrronium and indacaterol, as monotherapy and in combination, on the methacholine dose-response curve of mild asthmatics: a randomized three-way crossover study.
BACKGROUND
Methacholine dose-response curves illustrate pharmacologic bronchoprotection against methacholine-induced airway hyperresponsiveness and can be used to quantitate changes in airway sensitivity (position), reactivity (slope), and maximal responsiveness following drug administration. Our objective was to determine the influence of single-dose glycopyrronium (long-acting muscarinic antagonist) and indacaterol (ultra-long acting β agonist), as monotherapy and in combination, on the methacholine dose-response curve of mild asthmatics and to compare these findings with a non-asthmatic control curve.
METHODS
This was a randomized, double blind, double dummy, three-way crossover study. For asthmatic participants (n = 14), each treatment arm included a baseline methacholine challenge, drug administration, and repeat methacholine challenges at 1, 24, and 48 h. Non-asthmatic control participants (n = 15) underwent a single methacholine challenge and did not receive any study treatment. Methacholine dose-response curves were graphed as the percent fall in forced expiratory volume in 1 s (FEV) for each methacholine concentration administered. Best-fit curves were then generated. Differences in airway reactivity were calculated through linear regression. Changes in airway sensitivity were assessed as the shift in the provocative concentration of methacholine causing a 20% fall in FEV.
RESULTS
Compared to baseline, all treatments significantly reduced airway sensitivity to methacholine at 1 h post-dose (indacaterol ~1.5 doubling concentrations; glycopyrronium ~5 doubling concentrations; combination ~5 doubling concentrations). Bronchoprotection at 24 and 48 h remained significant with glycopyrronium and combination therapy only. Airway reactivity was not influenced by indacaterol whereas glycopyrronium significantly reduced airway reactivity at all time-points (p = 0.003-0.027). The combination significantly decreased slope at 1 (p = 0.021) and 24 (p = 0.039) hours only. The non-asthmatic control and 1-h glycopyrronium curves are nearly identical. Only the non-asthmatic control and 1-h post-combination therapy curves appeared to generate a true response plateau (three data points within 5%), which occurred at a 14% fall in FEV.
CONCLUSIONS
Methacholine dose-response curves differentiate the bronchoprotective mechanisms triggered by different classes of asthma medications. Assessment of bronchoprotection using methacholine dose-response curves may be useful during clinical development of respiratory medications when performing superiority, equivalence, or non-inferiority trials.
TRIAL REGISTRATION
clinicaltrials.gov ( NCT02953041 ). Retrospectively registered on October 24th 2016.
Topics: Adolescent; Adrenergic beta-2 Receptor Agonists; Adult; Aged; Asthma; Bronchial Provocation Tests; Bronchoconstrictor Agents; Bronchodilator Agents; Cross-Over Studies; Double-Blind Method; Drug Combinations; Female; Forced Expiratory Volume; Glycopyrrolate; Humans; Indans; Lung; Male; Methacholine Chloride; Middle Aged; Muscarinic Antagonists; Quinolones; Saskatchewan; Severity of Illness Index; Time Factors; Treatment Outcome; Vital Capacity; Young Adult
PubMed: 28768531
DOI: 10.1186/s12931-017-0628-4 -
Chest Feb 2020The respiratory duty cycle (T/T) can influence bronchoprovocation test results and nebulized drug delivery. The T/T has not yet been examined in individuals with airway...
BACKGROUND
The respiratory duty cycle (T/T) can influence bronchoprovocation test results and nebulized drug delivery. The T/T has not yet been examined in individuals with airway hyperresponsiveness (AHR) in typical bronchoprovocation test conditions. This study investigated the mean T/T in participants with and without AHR and whether the T/T changes with increasing bronchoconstriction.
METHODS
Fifteen participants with AHR and fifteen participants without AHR completed this randomized crossover study. An ultrasonic spirometer was used for continuous measurement of the T/T as participants inhaled room air or aerosolized solution. Each participant completed two methacholine challenges, one using a continuous-output vibrating mesh nebulizer/ultrasonic spirometer and one with the nebulizer only. Prior to each methacholine challenge, participants inhaled room air and aerosolized saline through the nebulizer/spirometer setup to record baseline T/T data.
RESULTS
The mean T/T findings [95% CIs] during room air inhalation were 0.392 [0.378-0.406] and 0.447 [0.426-0.468] in participants with and without AHR, respectively (P < .001). The mean T/T during saline inhalation were 0.389 [0.373-0.405] and 0.424 [0.398-0.450] in participants with and without AHR (P = .040). The T/T showed a nonsignificant downward trend with progressive methacholine-induced bronchoconstriction.
CONCLUSIONS
The mean T/T in participants with AHR closely resembles the assumed T/T of 0.40 recommended for standard use when calculating methacholine challenge results. Since the T/T did not change significantly over the course of a methacholine challenge, the same T/T can be used to calculate the dose of methacholine inhaled, regardless of the level of bronchoconstriction.
TRIAL REGISTRY
ClinicalTrials.gov; No.: NCT03505489; URL: www.clinicaltrials.gov.
Topics: Adolescent; Adult; Bronchial Provocation Tests; Bronchoconstrictor Agents; Case-Control Studies; Cross-Over Studies; Female; Forced Expiratory Volume; Humans; Inhalation; Male; Methacholine Chloride; Middle Aged; Random Allocation; Respiratory Hypersensitivity; Spirometry; Time Factors; Young Adult
PubMed: 31542451
DOI: 10.1016/j.chest.2019.09.005 -
Pediatric Pulmonology Aug 2019Forced expiratory maneuvers are usually difficult in young children. Impulse oscillometry (IOS) requires no active cooperation, is noninvasive, rapid, and easy to... (Observational Study)
Observational Study
Comparison of impulse oscillometry and spirometry for detection of airway hyperresponsiveness to methacholine, mannitol, and eucapnic voluntary hyperventilation in children.
BACKGROUND
Forced expiratory maneuvers are usually difficult in young children. Impulse oscillometry (IOS) requires no active cooperation, is noninvasive, rapid, and easy to perform. This study aimed to compare IOS indexes and forced expiratory volume in 1 second (FEV1) in children for the assessment of bronchial hyperreactivity to methacholine, mannitol, and eucapnic voluntary hyperventilation (EVH).
MATERIALS
Children aged 3-14 years (mean 10.0 ± 3.1) with symptoms suggestive of asthma were recruited. IOS measurements were taken before spirometry. Methacholine, mannitol, and EVH tests were performed without a specific order.
RESULTS
We included 190 children, whose mean age was 10.0 ± 3.1 years. Changes in FEV1 correlated significantly with variation in IOS indexes (P < .05). The indexes with the greatest discriminative capacity were Z5, R5, and X5. Optimal cut-offs were: for methacholine tests, ≧22% in R5, ≧82% for reactance area (AX), and ≦41% for X5; for the mannitol test, ≧18% in R5, ≧40% in AX, and ≦21% for X5. In the EVH test, ≧23% for R5, ≧40% for AX, and a fall of 29% for X5. When using the optimal cut-off points obtained from IOS, the mean number of steps and doses required for methacholine and mannitol tests to induce significant bronchoconstriction were significantly lower compared with spirometry ( P < .05).
CONCLUSIONS
The effectiveness of R5, X5, and AX indexes were comparable to FEV1 in assessing bronchial obstruction during bronchial challenge testing. Therefore, IOS may be useful in assessing bronchial obstruction in children who cannot reliably perform spirometric maneuvers during bronchial challenge testing.
Topics: Adolescent; Bronchial Diseases; Bronchial Provocation Tests; Child; Child, Preschool; Female; Forced Expiratory Volume; Humans; Hyperventilation; Male; Mannitol; Methacholine Chloride; Oscillometry; Respiratory Hypersensitivity; Spirometry
PubMed: 31211519
DOI: 10.1002/ppul.24409 -
Pharmacological Reports : PR Oct 2018Curcumin has shown various pharmacological effects such as anti-inflammatory activities. In this study, the effects of curcumin on tracheal responsiveness and lung...
BACKGROUND
Curcumin has shown various pharmacological effects such as anti-inflammatory activities. In this study, the effects of curcumin on tracheal responsiveness and lung pathological features were evaluated in a rat model of asthma.
METHODS
Tracheal responsiveness and lung pathological features were evaluated in control rats (C), ovalbumin (OVA)-sensitized rats (as an animal model of asthma; A), A rats treated with curcumin (Cu, 0.15, 0.30, and 0.60mg/ml) and dexamethasone (D, 1.25μg/ml), (n=8 in curcumin-treated groups and n=6 in other groups). Curcumin and dexamethasone were added to animals' drinking water during the sensitization period.
RESULTS
Asthmatic group showed increased lung pathological score and tracheal responsiveness to methacholine and OVA compared to control group (p<0.01 to p<0.001). Pathological features including interstitial inflammation, interstitial fibrosis, bleeding, and emphysema as well as tracheal responsiveness to methacholine and OVA, were significantly decreased in treated groups with dexamethasone and all concentrations of curcumin compared to group A (p<0.05 to p<0.001). Epithelial damage was also significantly decreased in treated groups with the two higher concentrations of curcumin (p<0.05 to p<0.001).
CONCLUSION
Curcumin showed preventive effects on tracheal responsiveness and lung pathological features in asthmatic rats.
Topics: Animals; Asthma; Curcumin; Dexamethasone; Dose-Response Relationship, Drug; Isometric Contraction; Lung; Male; Methacholine Chloride; Ovalbumin; Rats; Trachea
PubMed: 30107348
DOI: 10.1016/j.pharep.2018.04.007 -
Respiratory Physiology & Neurobiology Mar 2020Nocturnal worsening of asthma may be due to reduced lung volumes and fewer sigh breaths, which have been shown to increase airway resistance and bronchoreactivity. We... (Clinical Trial)
Clinical Trial
Nocturnal worsening of asthma may be due to reduced lung volumes and fewer sigh breaths, which have been shown to increase airway resistance and bronchoreactivity. We hypothesized that mimicking deep inspiration using nocturnal mechanical support would improve symptoms in patients with asthma. Subjects with asthma underwent usual care and bilevel positive airway pressure (PAP) therapy for 4 weeks, separated by 4 weeks, and methacholine challenge (PC) and subjective assessments. 13 patients with asthma alone and 8 with asthma + OSA completed the protocol. Change in bronchoreactivity (ratio of Post/Pre PC) was not significantly different during usual care and bilevel PAP [0.86 (IQR 0.19, 1.82) vs 0.94 (IQR 0.56, 2.5), p = 0.88], nor was the change in Asthma Control Test different: 0.1 ± 2.2 vs. -0.2 ± 2.9, p = 0.79, respectively. Bilevel PAP therapy for four weeks did not improve subjective or objective measures of asthma severity in patients with asthma or those with asthma and OSA, although there was heterogeneity in response.
Topics: Adult; Asthma; Bronchial Provocation Tests; Bronchoconstrictor Agents; Continuous Positive Airway Pressure; Cross-Over Studies; Female; Humans; Lung Volume Measurements; Male; Methacholine Chloride; Middle Aged; Outcome Assessment, Health Care; Sleep Apnea, Obstructive
PubMed: 31805396
DOI: 10.1016/j.resp.2019.103355 -
Pulmonary Pharmacology & Therapeutics Feb 2020Methacholine challenges have been used in clinical trials to assess therapeutic effects and potential adverse reactions of interventions on pulmonary function in a... (Clinical Trial)
Clinical Trial
BACKGROUND
Methacholine challenges have been used in clinical trials to assess therapeutic effects and potential adverse reactions of interventions on pulmonary function in a sensitive population, such as in subjects with asthma. Here, we evaluate the variability of the methacholine challenge recovery model, and compare the results obtained for both incremental and bolus challenge methods.
METHODS
The extent, time course and variability of change in forced expiratory volume in 1 s (FEV) following repeated methacholine challenges in subjects with mild asthma were investigated in an open-label, four-period, fixed-sequence, two-method, replicate crossover study. At Visits 1 and 2, subjects underwent an incremental challenge using doubling doses of methacholine until a ≥20% decrease in FEV was observed; at Visits 3 and 4, subjects underwent a bolus challenge, inhaling a single dose of methacholine calculated from the cumulative dose established during Visit 1.
RESULTS
A total of 19 subjects were included in the study. Both the mean FEV area under the curve (FEV AUC) and mean maximum reductions in FEV (absolute and relative) 120 min post-challenge values were higher for the incremental challenges than the bolus challenges, with no reported difference between repetitions of the same methodology. FEV AUC decrease 120 min post challenge demonstrated an intra-subject coefficient of variation (CV) of 47.2% (incremental) and 78.3% (bolus), suggesting considerable between-visit variability. The mean absolute, and similarly relative, maximum reductions in FEV compared with post-diluent baseline values demonstrated lower intra-subject variability (incremental 21.16%, bolus 40.67%) than the FEV AUC-based endpoint. There was a trend towards faster recovery following the bolus challenge than with the incremental challenge. The provocative dose of methacholine inducing a ≥20% decrease in FEV resulted in a between-group mean difference of 27.20% in the incremental challenge periods, with a high intra-subject CV of 80.64%, demonstrating considerable variability.
CONCLUSION
Maximum reduction in FEV had the lowest variability. There was little difference between repetitions of the same methodology, as indicated by overlapping confidence intervals. There was a trend towards faster recovery following bolus challenge than with the incremental challenge. The results of this trial could be of value when designing future clinical trials using the methacholine challenge methodology.
Topics: Administration, Inhalation; Adult; Aged; Aged, 80 and over; Anti-Asthmatic Agents; Asthma; Cross-Over Studies; Drug Delivery Systems; Female; Forced Expiratory Volume; Humans; Lung; Male; Methacholine Chloride; Middle Aged
PubMed: 31843704
DOI: 10.1016/j.pupt.2019.101876