PROTECTION AGAINST PULMONARY OXYGEN-TOXICITY IN RATS BY THE INTRATRACHEAL ADMINISTRATION OF LIPOSOME-ENCAPSULATED SUPEROXIDE-DISMUTASE OR CATALASE

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Abstract
To test the feasibility of using liposomes to deliver therapeutic agents to the lungs, the effect of liposome-encapsulated superoxide dismutase (SOD) or catalase on pulmonary O2 toxicity was studied in rats. The SOD or catalase was encapsulated in negatively charged multilamellar liposomes and administered directly into the trachea of adult rats, which were subsequently exposed to hyperoxia (> 95% O2). Response to hyperoxia was examined by studying lung SOD and catalase activities, survival rates and lung morphology. Rats receiving liposome-encapsulated SOD or catalase showed increased levels of enzyme activities in the lung homogenates compared with those in the control groups after 24-72 h of hyperoxic exposure. Elevated enzyme levels in the lungs of rats treated with liposome-encapsulated SOD or catalase were accompanied by a significant improvement in survival rates after 72 h of hyperoxic exposure and less lung injury than in the other control groups.