Role of Endogenous Nitric Oxide in Airflow Obstruction in Smokers (Results)

14 Dec
2013

Role of Endogenous Nitric Oxide in Airflow Obstruction in Smokers (Results)The two groups were age matched, and in both, pulmonary function was within the normal range, but FEVi o% and maximum expiratory flow at 25% and 50% vital capacity were significantly lower in smokers than in nonsmokers. In nonsmokers, the concentration of exhaled NO increased after breath-holding in a time-dependent manner (Fig 1). However, the concentration of exhaled NO was not affected by breath-holding in smokers. The level of exhaled NO was higher in nonsmokers than in smokers, and this difference became larger as breath-holding time increased. To evaluate the correlation between endogenous NO level in exhaled air and the degree of airflow obstruction in smokers, we used a new parameter. 

NO concentration difference (ANO), which we determined as follows: ANO=NO -N0; where NO is the concentration of NO in exhaled air after 15 s breath-holding, and NO is the concentration of NO in exhaled air during normal breathing. We found a positive correlation between ANO and airflow obstruction (FEVi o%) (Fig 2).
figure-1 

Figure 1. Top: NO in exhaled air measured by the sequential breath-holding method. Bars indicate breath-holding. A, Nonsmoker (33 years old); B, smoker (35 years old). Bottom: Comparison of NO concentrations in exhaled air by nonsmokers and smokers.

figure-2

Figure 2. Correlation between NO concentration difference (ANO) and airflow obstruction (FEVi.o%).

top