Moderate exercise decreases nitric oxide exhalation in patients with stable coronary artery disease

Nitric oxide (NO) is present in exhaled air in humans and its level may decrease in heart diseases. Nitrates are metabolised to NO. In the present study we prospectively investigated how coronary disease treated with oral nitrates and physical exercise influence the exhaled NO concentration (exNO). The study was performed in 44 patients with stable coronary artery disease (CAD) treated with oral nitrates (31 nonsmokers and 13 smokers). End-tidal concentration of exhaled NO was measured by the use of a chemiluminescence method. The Bruce protocol of an exercise test was performed in 21 coronary patients and 11 volunteers. NO was measured before and 2-5 min after the test. We found no significant differences in the exNO level between healthy controls and CAD patients as analyzed either for the whole groups or non-smoker and smoker subgroups (6.01 parts per billion (ppb) vs. 4.91 ppb; 7.02 ppb vs. 5,89 ppb; 3.62 ppb vs. 3.33 ppb, respectively). However, the coronary patients group, as a whole, had lower exNO after exercise (4.22 ppb vs. 3,84 ppb, P<0.01). The difference persisted after division of this group into non-smokers and smokers; 5.19 ppb vs. 4,79 ppb, P<0.05 and 3.63 ppb vs. 3.27 ppb, P<0.05, respectively). The level of exNO changed inappreciably after exercise in control subjects. We conclude that coronary disease and oral nitrates, in themselves, do not influence the exhaled NO concentration. Physical exercise, on the other side, lowers the exhaled NO level in coronary patients.