LATE-BREAKING ABSTRACT: Effects of growth and ageing on pulmonary nitric oxide dynamics in healthy subjects

The age dependence of NO parameters has not been addressed. We hypothesize that alveolar NO (C A NO) is affected by age and that F E NO 50 and airway flux (J aw NO) reflect airway surface. The lung matures up to the age of 20, hence age groups; young Healthy subjects (n=284) were investigated, see Table. There was only a gender difference in the middle age group for both J aw NO (p=0.001) and F E NO 50 (p=0.001). There was a correlation of J aw NO to both age (r=0.30, p=0.007) and height (r=0.38, p=0.002) in the young group, correlations were not found in the middle age group, but in the older group J aw NO correlated with age (r=0.23, p=0.024). C A NO was correlated to age in the middle group (r=0.32, p=0.001) as well as in the old group (r=0.48, p In the middle and older age groups pulmonary aging seems to increase C A NO possibly reflecting decreased diffusivity of gases in the acinar area. In the growing lung F E NO 50 and J aw NO were related to age and even more to height, possibly reflecting increasing bronchial mucosal surface area with increasing height. Further studies are needed before we can give age related reference values for the NO parameters.