PT - JOURNAL ARTICLE AU - A. Casas AU - F. P. Gómez AU - B. Dahlén AU - J. Roca AU - J. A. Barberà AU - S-E. Dahlén AU - R. Rodríguez-Roisin TI - Leukotriene D<sub>4</sub>-induced hypoxaemia in asthma is mediated by the cys-leukotriene<sub>1</sub> receptor AID - 10.1183/09031936.05.00147504 DP - 2005 Sep 01 TA - European Respiratory Journal PG - 442--448 VI - 26 IP - 3 4099 - http://erj.ersjournals.com/content/26/3/442.short 4100 - http://erj.ersjournals.com/content/26/3/442.full SO - Eur Respir J2005 Sep 01; 26 AB - Bronchoprovocation with cysteinyl-leukotrienes (LTs) induces airflow obstruction and gas exchange abnormalities, namely ventilation-perfusion ratio (V′A/Q′) imbalance. However, it is unknown which of the two different receptors for cysteinyl-LTs mediate these V′A/Q′ disturbances. In a double-blinded, crossover design, 10 patients with mild asthma were randomised to receive an oral single dose of the selective cysteinyl-LT1 receptor antagonist montelukast (40 mg) or placebo before leukotriene (LT)D4 inhalation challenge. Gas exchange, including V′A/Q′ descriptors were measured at baseline, 3 h after montelukast/placebo pretreatment and 5, 15 and 45 min after the LTD4 challenge. Compared with montelukast, inhalation of LTD4 induced a marked fall in forced expiratory volume in one second (mean±se 33±2%) and profound V′A/Q′ mismatching, reflected by a decreased arterial oxygen tension (from 100±4 to 75±3 mmHg) and an increased overall index of V′A/Q′ heterogeneity dispersion of retention minus excretion inert gases corrected for dead space (from 4.9±1.2 to 8.4±1.1; normal≤3.0; dimensionless), 5 min after placebo. Following montelukast, LTD4 produced no significant changes in any of the variables. In conclusion, these findings point to the view that leukotriene D4-induced gas exchange disturbances and bronchoconstriction are both mediated by the cysteinyl-leukotriene1 receptor.