ENDOGENOUS NITRIC-OXIDE IN EXPIRED AIR - EFFECTS OF ACUTE EXERCISE INHUMANS

Nitric oxide (NO) is present in the exhaled breath of humans and exper imental animals, but its physiologic role and cellular source(s) remai n to be determined. Possible sites of origin are pulmonary endothelial cells and/or resident macrophages. Here we have tested the hypothesis that changes in cardiovascular status can alter the apparent pulmonar y excretion of NO. Exercise on a stationary bicycle produced rapid and reversible increases in pulmonary NO excretion rate, and changes in N O excretion rate during exercise were well correlated with observed ch anges in heart rate. These results suggest that changes in expired NO during exercise are related to corresponding cardiovascular responses.