Gap junction channel protein connexin40 modulates rabbit pulmonary microvascular endothelial cells permeability in traumatic acute lung injury

Abstract

Objective To investigate the influence of traumatic acute lung injury (ALI) rabbit serum on gap junction channel ( GJC ) function and connexin40 ( Cx40) expression, and the correlation of GJC and Cx40 with rabbit pulmonary microvascular endothelial cells permeability. Methods Cultured pulmonary microvessel endothelial cells were divided into three groups, control ( Gcontrol) , injured serum (Gserum) , and blocker agent ( Gblocker). GJC function was assessed by scrape-loading and dye transfer techniques. Pulmonary microvessel endothelial cells permeability was measured by Evans blue-labeled albumin transfer, and the expression of Cx40 was measured by Western blotting. Intracellular free calcium concentration was measured by fluo-3am. Results Injured serum decreased GJC function and the level of Cx40,which was aggravated by the GJC blocker (control 726 293. 2 ± 83 684. 1, serum 397 798. 1 ± 87 145. 7, blocker 316 977. 6 ±76 325. 9,n=4,P ＜0. 05). Similarly, pulmonary microvascular endothelial cells permeability was increased significantly in Gserum and Gblocker as compared with Gcontrol (P ＜0. 05). After treatment with injured serum in combination with gap junction blocker in vitro, intracellular free calcium concentration was increased [control (494. 80 ±41.94) nmol/L, serum (569. 80 ±6. 70) nmol/L, blocker (158. 80 ±13. 09) nmol/L, P＜ 0.05]. Conclusion Traumatic ALI rabbit serum inhibits the Cx40 expression and down-regulates GJC function, which contributes to the increase of pulmonary microvascular endothelial cells permeability after ALI This mechanism may participate in the increase of pulmonary vascular permeability and promote the morbidity of ALI after trauma. Key words: Acute lung injury; Connexin40; Pulmonary permeability