Pulmonary surfactant, a complex lipoprotein, is secreted by alveolar type 11 cells. It lies at the alveolar air-fluid interface and prevents alveolar collapse by reducing surface tension. The high incidence of respiratory distress syndrome (RDS) in premature infants results principally from a deficiency of pulmonary surfactant. Surfactant protein A (SP-A) is the most abundant surfactant protein and reduces surface tension at the alveolar air-liquid interface in lung cells. In this study, RT-PCR and Western blot analyses of SP-A were performed to evaluate the biological activity of baicalin, a Chinese medicine prescribed extensively for preventing miscarriage. In in vitro experiments, lung adenocarcinoma cell line H441 was cultured with baicalin in varying concentrations and for varying lengths of time. The results show that the expression of SP-A gene was positively affected by baicalin in dose-dependent and time-course manners. The maximal expression of the SP-A gene, 1.7-fold greater than control, is induced at 150 nM of baicalin treated for 48 h.
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