Endothelin-1 expression in lung of ventilator-induced lung injury canine model

Objective To determine the change of endothelin-1 (ET-1) expression in the lung tissue of ventilator-induced lung injury (VILI) model. Methods The dogs were randomly divided into control group (N group, n =6) and acute lung injury (ALI) group ( n =14). ALI model was established by intravenously injecting with oleic acid. Thereafter two animals were obtained as ALI group, and the others were randomly divided into low tidal ventilation group (LV group, n =6) and high tidal ventilation group (i. e. VILI group, n =6). The tidal volume was respectively 6 ml/kg and 20 ml/kg in LV group and VILI group, and positive end expiratory pressure was 10 cm H2O. Lung tissues were stained with HE,the pathological changes of lung injury were evaluated with Smith scoring, the distribution of ET-1 was observed with immunohistochemistry technique, and changes of pathology and ET-1 expression in different groups were compared. Results There were widened alveolar septum, inflammatory cell infiltration,alveolar hemorrhage, exudation, and necrosis in LV group and VILI group. The lung injury score in LV group was lower than that in VILI group ( P <C0. 01). The immunohistochemistry results showed that small amount of ET-1 was expressed in pulmonary vascular endothelial cells and alveoli of N group,et-1 expression in pulmonary vascular endothelial cells and alveoli of LV group and VILI group was significantly higher than that in N group (all P < 0. 01), and ET-1 expression in VILI group was significantly higher than that in LV group ( P <0. 01). Conclusions ET-1 is overexpressed in pulmonary vascular endothelial cells and lung tissues of VILI model, which indicates that ET-1 may be involved in the pathophsiologic process of VILI. Key words: Ventilator-induced lung injury; Endothelin-1; Mechanical ventilation; Tidal volume; Acute lung injury