Objective  To investigate the expression and significance of connexin43 (Cx43) in the increased vascular permeability induced by LPS.   Methods  Rat vascular endothelial cells (VECs) were primary isolated from normal SD rats’ superior mesenteric arteries (SMAs)

and then cultured with treatment of 1

2

3 or 4 μg/ml LPS for 15 and 30 min

and 1

2

3

4

5

6 or 7 h. Cell vitality and permeability were determined with MTT assay and Transwell chamber technique respectively. The mRNA and protein expression of Cx43 were determined in the cells after 2 μg/ml LPS treatment.   Results  LPS at 1 and 2 μg/ml didn’t change the cell vitality

while 3 and 4 μg/ml LPS diseased it obviously (P0.01). LPS of 2 μg/ml increased the cell permeability (P0.01). The expression of Cx43 at mRNA and protein levels was gradually decreased after 2 μg/ml LPS treatment. VECs’ permeability and the expression of Cx43 had a negative correlationship.   Conclusion  Cx43 is involved in the regulation of vascular permeability following septic shock. Cx43 may be used to attenuate vascular permeability in septic shock.