Introduction The effect of montelukast therapy on bronchial hyperreactivity (BHR) as measured by the methacholine challenge test in preschool children has not yet been reported.
The methacholine challenge involves the inhalation of increasing concentrations of a substance that causes airway narrowing in those predisposed.
We chose to perform the methacholine provocation with the same methacholine concentrations for each mouse strain to make comparisons easier.
The methacholine aerosol was administered with a dosimeter (MFDC 88, Mediprom, Paris, France) attached to a nebulizer (De Vilbis 5610 D; particle size 1.9 µm MMAD).
After the methacholine challenge, the response was monitored and the peak airway resistance was recorded as a measure of airway hyperreactivity.
The EIB+ group had a slightly lower methacholine PC20 than the EIB− group (P = 0.01), resulting in a modest relationship between the maximum fall in FEV1 after exercise challenge and the methacholine PC20 (r2 = 0.43, P = 0.01).
In addition, formate was significantly correlated with two clinical variables (not measured in controls), namely the methacholine PC20 (for log-transformed formate, r = −0.39, p = 0.002) and serum IgE (r = 0.28, p = 0.016).
The mouse was subsequently ventilated with a Harvard pump ventilator (tidal volume = 0.4 ml, frequency = 120 breaths/min, positive end-expiratory pressure 2.5 3.0 cm H2O) and the tail vein was cannulated with a 27 gauge needle for injection of the methacholine challenge.
SRrs, slope of the methacholine dose-response curve for Rrs.
SRrs, slope of the methacholine dose-response curve for respiratory resistance.
The details of the methacholine challenge test have been reported previously.
