Exhaled nitric oxide and exercise-induced bronchoconstriction in asthmaticchildren

It is known that exhaled nitric oxide (ENO) is increased in asthmatic indiv iduals, probably as an expression of airway inflammation, but no studies ha ve been reported of ENO and exerciser-induced bronchoconstriction (EIB). We assessed the effect of a treadmill exercise challenge on ENO concentration in 24 asthmatic children aged 11.2 +/- 0.4 yr (mean +/- SEM). According to the presence or absence of EIB, the children were divided into an EIB grou p (n = 10) and a non-EIB group (n = 14). ENO was measured with a single-bre ath reservoir technique. FEV1 ENO, and heart rate were measured at baseline and 1, 6, 12, and 18 min after the end of exercise. We also measured ENO i n 18 healthy control children aged 10.8 +/- 0.6 yr, of whom nine underwent an exercise challenge identical to that of the asthmatic children. After th e exercise test, the mean decrease in FEV1 was 34% in the EIB group and 5% in the non-EIB group. The EIB group had higher baseline ENO values (12.3 +/ - 1.6 ppb) than the healthy children (6.1 +/- 0.2 ppb) (p < 0.01). The time course of ENO was similar in the EIB, non-EIB, and control groups, with no significant changes after exercise (p = NS). In the overall group of asthm atic children there was a significant correlation (r = 0.61, p < 0.01) betw een baseline (preexercise) ENO and magnitude of the maximal decrease in FEV 1 after exercise. In conclusion, our study shows that ENO levels do not cha nge during acute airway obstruction induced by exercise challenge in asthma tic children. In addition, baseline ENO values correlate with the magnitude of postexercise bronchoconstriction, suggesting that NO may be a predictor of airway hyperresponsiveness to exercise.