Gap junction channel modulates pulmonary vascular permeability through calcium in acute lung injury: an experimental study.
BACKGROUND
Increased pulmonary vascular permeability is a hallmark of acute lung injury (ALI). Gap junction channels (GJCs) connect adjacent cells and facilitate ion exchange. It remained unclear whether GJCs modulate pulmonary permeability in ALI through intracellular calcium.


OBJECTIVE
This study aimed to verify if GJCs in pulmonary microvessel endothelial cells (PMVECs) modulate pulmonary vascular permeability in ALI via intracellular calcium.


METHODS
Firstly, an animal model of ALI was studied using connexin 40 (Cx40) immunohistochemistry in the lung with Evans' blue (EB) leakage. Then cultured PMVECs were divided into three groups: G(control), G(serum) and G(blocker). Serum was obtained from animals with ALI following gunshot injury (injured serum). Initially, G(blocker) was treated with the blocker of GJCs, and then G(serum) and G(blocker) were stimulated with the injured serum, respectively. GJCs, the permeability of cell monolayers and intracellular Ca(2+) were assessed.


RESULTS
Cx40 time-dependently decreased, whereas EB leakage increased. Cx40 and EB leakage exhibited a strong inverse correlation (rho = -0.934, p < 0.05). Injured serum decreased GJCs and expression of Cx40, whereas the blocker aggravated this effect. Similarly, when PMVEC monolayer was treated with injured serum, both permeability and intracellular Ca(2+) increased. These effects were also aggravated with the blocker.


CONCLUSIONS
Depression of GJCs of PMVECs increased pulmonary vascular permeability in ALI; this effect may be mediated by the overload of intracellular calcium.
Zhang
Jinzhou
J
Department of Cardiovascular Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an, People's Republic of China.
Wang
Wen
W
Sun
Jing
J
Li
Qiang
Q
Liu
Jincheng
J
Zhu
Hailong
H
Chen
Tao
T
Wang
Hongbing
H
Yu
Shiqiang
S
Sun
Guocheng
G
Chen
Wensheng
W
Yi
Dinghua
D
D055371:Acute Lung Injury / Q000209:etiology / Q000378:metabolism*; D000818:Animals; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism*; D002199:Capillary Permeability; D002478:Cells, Cultured; D004396:Coloring Agents; D017630:Connexins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D042783:Endothelial Cells / Q000187:drug effects; D005070:Evans Blue; D017629:Gap Junctions / Q000378:metabolism; D019850:Heptanol / Q000494:pharmacology; D016209:Interleukin-8 / Q000097:blood; D007424:Intracellular Fluid / Q000378:metabolism; D008168:Lung / Q000098:blood supply / Q000166:cytology; D011817:Rabbits; D014409:Tumor Necrosis Factor-alpha / Q000097:blood; D014948:Wounds, Gunshot / Q000150:complications / Q000378:metabolism*; D000097003:Gap Junction alpha-5 Protein
D002118:Calcium; D004396:Coloring Agents; D017630:Connexins; D005070:Evans Blue; D019850:Heptanol; D016209:Interleukin-8; D014409:Tumor Necrosis Factor-alpha; D000097003:Gap Junction alpha-5 Protein