Abstract: Objective To study the role of surfactant protein C (SP-C) in rat lung of chronic obstructive pulmonary disease (COPD). Methods Forty healthy conventional Sprague-Dawley (SD) rats were randomly divided into four groups, normal control group (control group), smoke exposure group (smoking group), lipopolysaccharide group (LPS group), smoke exposure + Lipopolysaccharide group (COPD group). The arterialpartialpressureofoxygen (PaO2)andarterialpartialpressureofcarbondioxide pathological (PaCO2) were detected. The ultrastructure of lung tissue were observed by transmission electron microscope. Enzyme-linked immuno sorbent assay (ELISA) were performed to determine protein expression of SP-C in lung and bronchoalveolar lavage fluid (BALF). RT-qPCR were performed to determine mRNA expression of SP-C in lung. Results Compared with control group, smoking group and LPS group, the PaO2 of COPD group was obviously lower, the PaCO2 of COPD group was obviously higher; the ultrastructure and histological analysis of lung tissues showed chronic inflammatory injury; Compared with control group, the expression of SP-C protein in was reduced, as well as SP-C mRNA expression. Conclusions The expression of SP-C in lung of rats COPD model down-regulated. SP-C may be involved in COPD.

Key words: chronic obstructive pulmonary disease, Surfactantassociated protein C, respiratory function