Methods
Type 1 and 2 cells were isolated from lung epithelium. After hypoxia reoxygenation treatment, the primary cell cultures were transfected with a plasmid over-expressing PBEF. Sodium-potassium ATPase (NKA), epithelial sodium channel (ENaC), type I cell marker rT140, surfactant protein (SP) and PBEF protein were analyzed at mRNA and protein levels using PCR and Western blot analysis. Immunofluorescence assays showed type 1 and 2 cells were successfully isolated. After the transfection with PBEF over-expression vector, PBEF and RTI40 levels were increased, while ENaC and SP as well as NKA, were decreased in both cells. It is clear that PBEF negatively regulates the expression of ENaC and NKA in the Na+ and fluid transport in lung epithelial cells.