Effect of Sodium Cromoglycate on Mast Cell Mediators during Hyperpnea in Athletes

The role of mast cells in the airway response to exercise and the benefit of sodium cromoglycate (SCG) in athletes are unclear. The purpose of this study was to clarify the role of mast cell mediators in the airway response to exercise in athletes and to investigate the effect of SCG. Eleven athletes with exercise-induced bronchoconstriction (EIB+) and 11 without (EIB-) performed a eucapnic voluntary hyperpnea (EVH) test (a surrogate for exercise) 10 min after inhalation of a placebo or 40 mg of the mast cell stabilizing agent sodium cromoglycate. The urinary concentrations of 9a,11β-PGF2 (a metabolite of PGD2 and a marker of mast cell activation) and leukotriene E4 (LTE4) were measured by enzyme immunoassay 60 min before and for 90 min after the challenge. In the EIB+ group, the maximum fall in forced expiratory volume in 1 s (FEV1) of 20.3% ± 3% on placebo was reduced to 11.5% ± 1.9% after SCG (P = 0.003). There was an increase in the urinary excretion of 9α,11β-PGF2 on the placebo day after EVH in both groups (P < 0.05) that was abolished by SCG. In the EIB+ group, there was also an increase of urinary LTE4 on the placebo day that was abolished by SCG, whereas the urinary excretion of LTE4 was inconsistent in the EIB- group. The results support mast cell activation with release of bronchoconstrictive mediators after hyperpnea in athletes with and without EIB and inhibition by SCG. The degree of airway responsiveness to the specific mediator released is likely to determine whether or not bronchoconstriction will occur after EVH.