Inactivation of lung surfactant is characterized by increased conversion of heavy (H) to light (L) subtypes as identified on sucrose gradients. A protease(convertase) has been implicated as a factor responsible for this conversion during surface-cycling of natural surfactant.
We studied the effects of oxidants on the proportion of L to H (L/H) aggregates (by phospholipid analysis) after surface cycling for 24 h at 37°C of natural lung surfactant (NLS), Beractant (Ber), and KL4 surfactant containing synthetic peptide leucine/lysine. With these surfactants, oxidant exposure caused significant inhibition of minimum surface tensions to >20 mN/m. In all surfactants tested, the unoxidized form had L/H of 8-10%. In Ber the L/H with OCl- (1 mmol/l) was 23.1%, with ONOO- (2 mmol/l) 13.0%, and with Fenton reactants (30 mmol/l H202 + 0.065-0.65 mmol/l FeCl2)(F) 0.0%. In KL4 the L/H with OCl- was 29.1%, with ONOO- 14.1%, and with F 0.0%. In NLS, Ber and KL4 F generated an ultraheavy band with surface activity >20 mN/m.
Oxidative inactivation of surfactant causes increased L/H independent of convertase activity; however, it may be synergistic with protease effectsin vivo. F may inactivate surfactant by molecular mechanisms different from that of OCl- and ONOO-, such as oxidative effects on proteins or peptides. Supported by R.W. Johnson PRI.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Andersson, S., Kheiter, A., Manalo, E. et al. OXIDATIVE INACTIVATION OF SURFACTANT † 1929. Pediatr Res 39 (Suppl 4), 324 (1996). https://doi.org/10.1203/00006450-199604001-01953
Issue Date:
DOI: https://doi.org/10.1203/00006450-199604001-01953