Unfractionated heparin attenuates lung vascular leak in a mouse model of sepsis:Role of RhoA/Rho kinase pathway

Excessive vascular permeability is a characteristic feature of ALI. We have previously demonstrated that UFH prevents LPS-induced disruption of endothelial barrier function in vitro. It was the objective of this study to determine whether UFH may attenuate endotoxin-induced lung vascular leak in mice and to further explore the possible underlying mechanisms.C57BL/6J mice were randomly divided into the control, LPS and LPS plus UFH groups. Sepsis was induced by intraperitoneal injection of LPS at a dose of 30 mg/kg. Mice in the LPS plus UFH group were intravenously received 8 units UFH (heparin sodium) diluted in 20 μl sterile saline at 0.5 h before the injection of LPS.1) UFH pretreatment attenuated LPS-induced histopathological changes in Lung at 6 h; 2) Pretreatment of mice with UFH ameliorated LPS-induced lung edema and lung vascular leak at 6 h; 3) UFH pretreatment dramatically inhibited RhoA and ROCK activation in the lung tissues of LPS-treated mice (3 and 6 h). 4) UFH pretreatment significantly down-regulated ROCK1 gene expression, but did not affect the increased expression of ROCK2 mRNA in the lung tissues of LPS-treated mice at 3 or 6 h.These data suggest that UFH may attenuate endotoxin-induced lung vascular leak by regulating RhoA/Rho kinase pathway.