EFFECT OF GRAVITY ON LUNG EXHALED NITRIC-OXIDE AT REST AND DURING EXERCISE

Exhaled nitric oxide (NO) from the lungs (V-NO) in nose-clipped subjec ts increases during exercise. This may be due to endothelial shear str ess secondary to changes in pulmonary blood flow. We measured V-NO aft er modifying pulmonary blood flow with bead-out water immersion (WI) o r increased gravity (2 Gz) at rest and during exercise. Ten sedentary males were studied during exercise performed in air and WI. Nine subje cts were studied at 1 and 2 Gz. Resting NO concentrations in exhaled a ir ([NO]) were 16.3 +/- 8.2 ppb (air), 15 +/- 8.2 ppb (WI) and 17.4 +/ - 5 ppb (2 linearly with V-O2, V-E and fH during exercise in air, WI a nd at 2 Gz. These relationships did not differ among the experimental conditions. Therefore, changes in pulmonary blood flow failed to alter the output of NO exhaled from the lungs at rest or during exercise. ( C) 1997 Elsevier Science B.V.