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...

BACKGROUND Unrestrained plethysmography has been used to monitor bronchoconstriction because of its ease of use and ability to measure airway responsiveness in conscious animals. However, its reliability remains controversial. OBJECTIVE To investigate if unrestrained plethysmography could provide a valid interpretation of airway responsiveness in allergic BALB/c mice. METHODS Ovalbumin sens...

Nitric oxide (NO), which can be derived from the nervous system or the epithelium of the airway, may modulate airway responsiveness. We investigated how NO derived from the airway nervous system would affect the airway responsiveness to histamine and acetylcholine in mechanically ventilated guinea pigs. An NO synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME) (1 mmol/kg i.p.) signific...

Previous studies have demonstrated that chronic mechanical strain produced by continuous positive airway pressure (CPAP) reduces in vivo airway reactivity in rabbits and ferrets. For CPAP to potentially have a therapeutic benefit for asthmatic subjects, the reduction in airway responsiveness would need to persist for 12-24 h after its discontinuation, require application for only part of the da...

Major basic protein and other native cationic proteins increase airway hyperresponsiveness when administered to the luminal surface of the airways in vitro. To determine whether the same applies in vivo, we assessed airway responsiveness in rats challenged with both aerosolized and intravenously infused methacholine. We partitioned total lung resistance into its airway and tissue components usi...

In a recent editorial (May 1993; 48: 470-3) Drs van Schayck and van Herwaarden present a surprisingly ambivalent account of the effects of agonist treatment on airway responsiveness. Their conclusion that agonists have an unimportant effect on responsiveness appears to be based on recent analyses of data from their own study.' However, a thorough review of the studies discussed by van Schayck a...

We wished to determine whether the refractory period after hypertonic saline (HS) challenge is due to mast cell mediator depletion. Therefore, the airway responsiveness to adenosine 5' monophosphate (AMP), which induces bronchoconstriction via mast cell histamine release, was determined after the inhalation of HS aerosol. Nine asthmatic subjects attended the laboratory on three occasions. On da...

The mechanical stress imposed on the lungs during breathing is an important modulator of airway responsiveness in vivo. Our recent study demonstrated that continuous positive airway pressure applied to the lungs of nonanesthetized, tracheotomized rabbits for 4 days decreased lower respiratory system responsiveness to challenge with ACh (Xue Z, Zhang L, Ramchandani R, Liu Y, Antony VB, Gunst SJ,...

Inhalational insulin was withdrawn from the market due to its potential to produce airway hyper-reactivity and bronchoconstriction. So the present study was designed to explore the acute effects of insulin on airway reactivity of guinea pigs and protective effects of salbutamol and ipratropium against insulin induced airway hyper-responsiveness on isolated tracheal smooth muscle of guinea pig. ...