[The expression and function of pulmonary surfactant protein A in severe acute pancreatitis in rats].

OBJECTIVE: To investigate the expression and function of surfactant protein A (SP-A) in lung in rats with acute lung injury (ALI) induced by severe acute pancreatitis (SAP). METHODS: Twenty Sprague-Dawley (SD) rats were randomly divided into 2 groups: sham operation group (sham, n=10) and SAP model group (SAP, n=10). SAP model was reproduced in SAP group. In sham group laparotomy only was done. Serum amylase (AMY) levels, partial pressure of oxygen in artery (PaO2) and lung wet/dry (W/D) ratio were determined. SP-A mRNA expression in lung was detected by reverse transcription-polymerase chain reaction (RT-PCR). SP-A protein expression in lung tissues was assessed by immunohistochemistry. The pathologic changes in pancreas and lung were observed 24 hours after reproduction of the model. RESULTS: Compared with sham group, PaO(2) in SAP group was decreased significantly [(96.78+/-3.81) mm Hg vs. (79.24+/-5.84) mm Hg, 1 mm Hg=0.133 kPa, P<0.05]. Serum levels of AMY and W/D ratio in SAP group were remarkably higher than that in sham group [(1 193.41+/-192.54) U/L vs. (7 144.19+/-727.91) U/L, 3.70+/-0.90 vs. 8.57+/-2.45, both P<0.05]. The expression of SP-A mRNA in lung tissues in SAP group was significantly down-regulated compared with that in sham group (1.21+/-0.10 vs. 0.80+/-0.11, P<0.05). The expression of SP-A protein in lung in SAP group was significantly decreased than that in sham group (7 982.22+/-3 689.57 vs. 3 497.99+/-2 958.21, P<0.05). The pathologic changes in pancreas and lung were marked in SAP group. The expression of SP-A protein and mRNA showed significant negative correlation with the extent of lung injury (r1= -0.876, P<0.01; r2= -0.713, P<0.05). CONCLUSION: SP-A decreases remarkably in ALI induced by SAP. Type II alveolar epithelial cells might play an important role in ALI induced by SAP.