Study On The Correlation Between Connexin40 And Lung Vascular Permeability

Objective: To observe the expressions of connexin40 and VE-cadherin at different durations of the acute lung injury(ALI) model of C57BL/6 mice and explore the functional correlation between connexin and lung vascular permeability.Methods: C57BL/6 mice were treated with LPS(0.01 mg/g) intraperitoneally for 24 hours, and then weight gain at baseline and after elevation of left atrial pressure in isolated perfused lungs were measured by PLUGSYS system. Connexin40 and VE-cadherin protein levels at 6h, 24 h, 72 h post-LPS treatment were measured by Western Blot, respectively. To explore correlation between connexin40 and lung vascular permeability, weight gains in isolated perfused lungs at baseline and after bolus infusion of PAF in the absence(PAF) or presence of gap2740(0.02 mg/m L;gap2740, PAF) or carbenoxolone(1mg/ml; carbenoxolone, PAF) were measured by PLUGSYS system, respectively. In addition, resistance changes at baseline and after treatment of thrombin in the absence(thrombin) or presence of carbenoxolone(carbenoxolone, thrombin) were recorded in ECIS, respectively. To further identify whether Cx40 knockout could have effect on lung vascular permeability, weight gains in isolated perfused lungs of Cx40+/+ and Cx40–/– mice at baseline and after bolus infusion of PAF were measured by PLUGSYS system,respectively.Results: Increase of weight gain at 24 h post-treatment of LPS was more than control group significantly following elevation of left atrial pressure so that intraperitoneal LPS-treatment could effectively reproduce the model of ALI. Western Blot analysis showed that, the expressions of connexin40 and VE-cadherin were lower at 6h post-LPS treatment compared with control levels. The expression still declined to a very low levels at 24 h post-LPS treatment. At 72 h post-LPS treatment, Connexin40 and VE-cadherin protein levels begain to return. Perfusion of mouse lungs with PAF caused severe edema, but application of Cx40-specific inhibitory mimetic peptide gap2740 or connexin inhibitor carbenoxolone to isolated perfused mouse lungs reduced the extent of PAF-induced edema. Results of ECIS showed that thrombin increased pulmonary endothelial permeability, which chould be attenuated by carbenoxolone.Also, PAF-induced edema in isolated perfused lungs of Cx40 deficiency mice was blocked.Conclusions: Our data reveal that endothelial Cx40 and VE-cadherin levels vary during recovery from endotoxin-induced lung injury. In addition, blockage or knockout of Cx40 could attentuate increased lung vscular permeability. Future studies are needed to elucidate further correlation between Cx40 and lung vascular permeability, especially regarding the roles of Cx40-regulatory mechanisms in lung vascular permeability.