Oxygen therapy and hyaline membrane disease: the effect of hyperoxia on pulmonary superoxide dismutase activity and the mediating role of plasma or serum.

In vitro and in vivo hyperoxic exposure of the lungs of normal immature animals resulted in a rapid increase of pulmonary superoxide dismutase activity. The increase of pulmonary SOD activity with in vitro hyperoxic exposure requires the presence of plasma or serum in the incubation medium. Twenty-three out of 26 plasma samples from premature infants without hyaline membrane disease were found to support the hyperoxic increaase of pulmonary SOD activity, whereas only five of 15 plasma samples from infants with HMD were effective. A defective plasma-lung interaction in infants with HMD may result in an inability to increase pulmonary levels of this presumed protective enzyme during hyperoxic therapy.