Experimental study on prevention of simulated high altitude ALI by tetramethylpyrazine in dogs

Twenty-one hybird dogs were randomly divided into acute lung injury (ALI) treated and control groups at simulated high altitude environment of 4000 m. All animals were sacrificed after 6 h. The tetramethylpyrazine (IMP) treated group showed that the WBC count was significantly higher at 15 min after fat tissue extract was given (P < 0.05), the edema of both capillary endothelial cells and alveolar epithelial cells was less serious, the number of leukocytes accumulated in the lungs was less. The increase in production of leukotriene B (LTB) by polymorphonuclear neutrophil (PMN), alveolar macrophage (AM), and the activity of platelet-activating factor (PAF) by PMN were partially inhibited (P < 0.01). Although the ratio of the pulmonary extravascular water volume/blood free dry lung weight (PEWV/BFDL) of TMP group was significantly elevated as compared with that of control group, no significant difference was seen (P > 0.05). However, the level of PaO₂, the PMN and AM count, and the albumin level of the BALF in both groups had no significant difference. These results demonstrated that the early treatment with TMP could inhibit the decrease in the WBC count, and reduce the accumulation of leukocytes in the lungs.