Through the determination of manifesting features of NOS in the lung tissues of rats of experimental "deficiency of lung qi syndrome"

it was found that there were more macrophages in the interstitial tissue of the lung with positive dense reaction

demonstrating that

under the condition of "deficient lung - qi"

the NO in the immune activity of macrophages possessed important mediation action. The increase of NO synthesis was an active action of "lung - qi" against pathogens. When the invasion of pathogens persisted

causing further deficiency of the lung - qi

and the dilating vessel action of NO decrease in the blood supply of lung tissue

resulting in "blood-stasis".