Clq Content of Serum and Lung Lavage Fluid of Rats Exposed to Toxic Levels of Oxygen

Abstract

We used a sensitive hemolytic assay to measure the level of Clq, a subcomponent of the first complement protein in the classic pathway, in bronchoalveolar lavage fluid and serum of rats exposed to air and hyperoxia. The serum level was 125 ± 5 μn/ml and the lavage level was 41. ± 17 ng/ml in rats breathing air. In rats exposed to acute oxygen toxicity (95% O₂ for 56 hr), the serum level was at 107 ± 10 μn/ml, but the level in lavage fluid increased to 2457 ± 400 ng/ml (p < 0.05 compared to air). Administration of the proline analogue cis-4-hydroxy-L-proline to air-and O₂-exposed rats reduced the serum Clq level by 28% and 34%, respectively (both p < 0.05), presumably by interfering with metabolism of the collagen-like sequence of Clq. The level of Clq in bronchoalveolar lavage fluid is a sensitive marker of acute lung injury.

Key Words:

• Complement
• Lung injury
• Oxygen toxicity
• Proline analogues
• Lung lavage