Exhaled Nitric Oxide Decreases during Exercise-induced Bronchoconstriction in Children with Asthma

Abstract

Nitric oxide (NO) produced in the airways can be either detrimental or protective to the host. To investigate the role of NO in the pathogenesis of exercise-induced bronchoconstriction (EIB), we measured exhaled NO (ENO) after exercise challenge in 39 asthmatic and six normal children. FEV(1) and ENO were measured before and at 0, 5, 10, and 15 min after exercise performed on a treadmill for 6 min. EIB was defined as a decrease in FEV(1) of more than 15% after the exercise. Normal children (control group) did not have EIB. Twenty-one patients with asthma had EIB (EIB group) whereas the remaining 18 patients did not (non-EIB group). The baseline ENO value was significantly higher in the asthmatic children than in the normal children, and there was a positive correlation between the maximal percent decrease in FEV(1) and the baseline ENO value (r = 0.501, p = 0.012). At the end of the exercise, ENO had decreased in all the subjects. In the non-EIB and control groups, ENO rebounded to above the baseline at 5 min after the exercise and thereafter. In contrast, ENO remained at a decreased level in the EIB group. The change in ENO did not correlate with the change in minute ventilation, and beta-agonist inhalation at the peak of EIB that accelerated the recovery of FEV(1) did not affect the depressed level of ENO, demonstrating that the reduction of ENO is not a simple consequence of increased ventilation nor airway obstruction. Among the EIB group, steroid-treated patients showed sooner recovery in ENO after the exercise than steroid-naive patients. Our study suggests that NO production in response to exercise may be impaired in patients with EIB, and that ENO represents not only airway inflammation but also a protective function of NO in EIB.

Exercise-induced bronchoconstriction alters airway nitric oxide exchange in a pattern distinct from spirometry

“…These observed changes last for only a short time (Ͻ5 min) postexercise, until ventilation rate returns to baseline. In contrast, exhaled NO concentration in asthma has been reported to be significantly reduced shortly after exercise (9,48,50), and the degree of EIB is significantly associated with atopy and baseline exhaled NO (37). These observations are consistent with our current findings in asthmatic and healthy subjects.…”

“…Mean (SD) W 50 for subjects with EIB at baseline was 206 (52) and was not impacted by the exercise challenge or bronchodilator. Mean (SD) Cpeak NO , W 50 , and A I,II values for healthy controls at baseline were 72 (32) ppb, 190 (48) ppb, and 12,822 (6,571) ppb/ml respectively, and were not impacted by the exercise challenge or bronchodilator (see Fig. 2).…”

Cough and exhaled nitric oxide levels: what happens with exercise?

“…Further, the fall in FeNO was small and within the coefficient of variant of the FeNO instrument used. Nevertheless, our data supports the findings of Terada et al (8) but are in contrast to Scollo et al (9) However, our study adds further novel data as neither studies examined FeNO in children with cough but without asthma. The fall in FeNO post exercise was larger in children with EIB and this difference between groups did not reach statistical significance.…”

Exhaled nitric oxide in childhood asthma: a review

“…Several studies found short acting b 2 -agonists to increase FE NO levels, probably by their effect on airway calibre and hence ventilated airway surface [115,46], but other studies could not confirm this [47]. While most studies did not find an effect of long acting b 2 -agonists (LABA) on FE NO , neither as monotherapy or added to ICS [116][117][118], one stuy did [119].…”