Rate of nitric oxide release in the lung and factors influencing the concentration of exhaled nitric oxide

Am J Physiol. 1996 Jun;270(6 Pt 1):L914-20. doi: 10.1152/ajplung.1996.270.6.L914.


The level of nitric oxide (NO) in exhaled air fluctuates in normal individuals depending on the physiological conditions. We evaluated the effects of duration of exhalation and breath-holding on the exhaled concentrations of NO in 16 normal human volunteers. Exhaled gas corresponding to vital capacity was collected in 6-liter Tedlar bags and analyzed by chemiluminescence. The NO concentration in exhaled gas increased significantly in proportion to the duration of exhalation [P = 0.009 +/- 0.011 (SD)] and was increased after breath-holding. There was no significant difference in the exhaled NO concentration among 10-s phases of a 30-s exhalation, as determined from multiple breath collections. The NO released from the airways is presumably unaffected by fluctuation of exhalation speed. The NO release rate, calculated from a single regression analysis between the NO concentration and the duration of exhalation, was 39 +/- 29 pmol/s, a value which was about fourfold greater in nine patients with bronchial asthma.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Carbon Dioxide / physiology
  • Female
  • Humans
  • Lung / metabolism*
  • Male
  • Methods
  • Nitric Oxide / metabolism*
  • Osmolar Concentration
  • Pulmonary Alveoli
  • Respiration*
  • Respiratory Dead Space
  • Time Factors


  • Carbon Dioxide
  • Nitric Oxide