To study the mechanisms and kinetics underlying the development of increased airway responsiveness (AR) after allergic sensitization, animal models have been invaluable. Using barometric whole-body plethysmography and increases in enhanced pause (Penh) as an index of airway obstruction, we measured responses to inhaled methacholine in conscious, unrestrained mice after sensitization and airway ...

We elucidated the interaction of small-conductance Ca(2+)-activated K(+) (SK(Ca)) channels and L-type Ca(2+) channels in muscarinic receptor-mediated control of catecholamine secretion in the isolated perfused rat adrenal gland. The muscarinic agonist methacholine (10-300 microM) produced concentration-dependent increases in adrenal output of epinephrine and norepinephrine. The SK(Ca) channel b...

BACKGROUND Bronchial hyperresponsiveness (BHR) to methacholine has been reported to occur in most lung transplant recipients. BHR to physical stimuli such as exercise and non-isotonic aerosols has not been as extensively studied in this subject population. This report aims to assess the presence and degree of BHR to methacholine and hypertonic saline in stable lung transplant recipients and to ...

Bronchodilator response (BDR) is assessed to estimate the reversibility of airflow obstruction. Bronchial hyperresponsiveness (BHR) is a characteristic feature of asthma and is usually measured by means of bronchial challenges using direct or indirect stimuli. The aim of the present study was to compare BHR to methacholine (direct) and that to adenosine 5'-monophosphate (AMP) (indirect) with re...

The relevance of increased methacholine airway responsiveness detected in children with no current or past symptoms of asthma is not known. We wished to determine whether the presence of airway hyperresponsiveness in asymptomatic children is also associated with abnormal variability of peak expiratory flow (PEF). In 12 asymptomatic children with methacholine hyperresponsiveness, we examined the...

The prevalence of bronchial hyperreactivity to inhaled methacholine and of a clinical history of symptoms of asthma was determined in a birth cohort of 9 year old New Zealand children. A history of current or previous recurrent wheezing was obtained in 220 of 815 children. Of 800 who had spirometric tests, 27 (3.4%) had resting airflow obstruction (FEV1/FVC less than 75%). Methacholine challeng...

Airway responsiveness to methacholine varies between normal people and is increased in patients with asthma. The importance of airway smooth muscle sensitivity in determining in vivo responsiveness is unknown. We have examined this question by comparing in vivo airway responsiveness with in vitro airway smooth muscle sensitivity to methacholine in 10 patients undergoing thoracic surgery. In viv...

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. Me...

The role of calcium in the relaxations evoked by methacholine and A23187 in intact rabbit aortic rings was investigated. Methacholine (10(-8) to 10(-6) M) and the calcium ionophore A23187 (10(-8) to 10(-6) M) produced dose-dependent relaxations of rings which had been contracted with the alpha-adrenergic agonist phenylephrine. The ability of a ring to relax in this manner was correlated with th...

The bronchoconstrictor potency of inhaled methacholine is widely used to assess airway responsiveness. However, evidence has accumulated that methacholine inhalation challenge may lead to an inflammatory response in the lower respiratory tract. We therefore compared cellular, leukotriene and prostanoid profiles in bronchoalveolar lavages (BAL) obtained five hours after methacholine challenge to...