Antioxidant-surfactant liposomes mitigate hyperoxic lung injury in premature rabbits. Walther, Frans J., Remedios David-Cu, Susanna L. Lopez. Department of Pediatrics, Charles R. Drew University of Medicine and Science & University of California Los Angeles School of Medicine, Los Angeles, California 90059.
APStracts 2:0105L, 1995.
Surfactant liposomes, encapsulating CuZn-superoxide dismutase (SOD) and catalase, increase alveolar type II cell antioxidant activity and protect cells against oxidant stress. We examined whether intratracheal instillation of antioxidant-surfactant liposomes increases lung antioxidant activity in premature rabbits. Pregnant New Zealand White rabbits were delivered by cesarean section on day 28 or 29 of gestation or allowed to deliver spontaneously. After premature birth or at 2 d of age in the term rabbits, the pups from each litter were divided into 4 groups. One group received 0.1 ml/15 g birth weight of antioxidant-surfactant liposomes by intratracheal injection and was then exposed to hyperoxia (&GT95% oxygen) for 24 h and killed. The second group received an equal amount of surfactant liposomes without antioxidant enzymes and hyperoxia for 24 h. The third group received air placebo and hyperoxia for 24 h and the fourth group was killed after birth if premature or at 2 d of age if term. After sacrifice, lung homogenates were investigated for total SOD and catalase activity and DNA content. Each treatment group consisted of 12-15 rabbit pups. Lung antioxidant enzyme activity increased with advancing maturity. Among the premature rabbits, total lung SOD and catalase activity were lowest in the pups killed before hyperoxia and the air placebo controls exposed to hyperoxia, intermediate in the pups treated with liposomes without antioxidant enzymes and hyperoxia, and highest in the pups that received antioxidant-surfactant liposomes and hyperoxia. Among the term rabbits, lung antioxidant enzyme activity was lowest in the pups killed before hyperoxia, highest in the pups who received antioxidant-surfactant liposomes and hyperoxia, and intermediate and similar in pups treated with air placebo or surfactant liposomes and hyperoxia. These data suggest that intratracheal instillation of surfactant liposomes boosts lung antioxidant capacity in premature rabbits exposed to hyperoxia with a further elevation in antioxidant activity in pups treated with surfactant liposomes encapsulating SOD and catalase. 

Received 18 October 1994; accepted in final form 12 June 1995.
APS Manuscript Number L298-4.
Article publication pending Am. J. Physiol. (Lung Cell. Mol.
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 11 July 1995.