| Background and Objectives pulmonary thromboembolism (PTE) is a kind of disease, in which lung artery system or its branches is obstructed by embolus who mostly comes from vein system or right heart. PTE is the most frequent type of pulmonary embolism(PE), and it occupies a large part of PE. In the world, pulmonary thromboembolism continues to be responsible for substantial morbidity ,high mortality and misdiagnostic rate, which have severe negative effect on treatment and diagnose. Clinical presentations of are so complicated and variable that it is often misdiagnose. In China, PTE was traditionally considered as a rare disease, and in a great extent resulted in ignoring to identify and diagnose it. Over the years, however, a number of observations has challenged this concept. Attaching importance to pulmonary thromboembolism in hospital, doctors find that morbidity rate has an increasing trend . As a result, it become a ordinary cardiopulmonary disease. Recently, because pathogenesis, early diagnose and effective treatment are not thorough researched, it is urgent to discuss pulmonary thromboembolism in rabbits by studying on pathophysiology of PTE.In the past years, most study on pathophysiology of PTE focus on vessel activating matter which associates with nervous system or body fluid, for example, thromboxaneA2, platelet activating factor, endothelin-1 and 5-hydroxytryptamine.Many scholars tried to look for the inhibition of vessel activating matter, but not make the breakthrough now. Recently, they pay attention to connection between the inflammatory response and shaping thromboembolism, in which cytokine play importance role. The study on TNF α and IL-6 widely range from cardiovascular and hematologic disease to lung disease, but a great shortage of them in PTE is common. In the present study, we consecutively investigated the level of TNFa and IL-6 on different time points before and after acute PTE model of rabbits by injection of autologous blood clots stabilized in a temperature-controlled (70℃) of distilled water for ten minutes through the femoral vein . Thus we tested function of those two factors in PTE, and tried to understand pathophysiological alterations in connection with pulmonary thromboembolism, and present new thoughts that may help prognosis clue and treatment measure of PTE.in the earlier period.Materials and methods Twenty-six rabbits were randomly divided into either PTE group (n=13) or control group (n=13). Pulmonary thromboemoblism model of rabbits were established with injection of autologous blood clots stabilized in a temperature-controlled (70℃) of distilled water for ten minutes through the femoral vein. 2ml blood was collected form earlap vein of rabbits periodically. Blood was put into a sterile testtube which was placed about 1 hour in air. Blood samples were discentered for twenty minutes at 3000 rotates per minute under temperature 4℃ ,then were stored in temperature -80 ℃ in refrigerator.The pulmonary thromboemoblism model of rabbits were explored at dissection and upon microscopical examination after they were killed on the 9th day . The dynamical changes of tumor necrosis factor-a and interleukin-6 in blood was observed by ELISA or radioimmunoassay. The data were analysed by software SPSS 10.0. T-test was used to compare the difference between two groups and repeated measures ANOVA was used to compare between before and after PTE. P value<0.05 is considered as statistically significant.Results 1. The 13 rabbits of PTE group all had symptoms including increase of respiratory tachycardia, panting, dysphoria, ect. The 13 rabbits of control group were normal.2. Petechial and patchy hemorrhages were observed on the surfaces of emboliclungs. The injected blood clots and secondary thrombus in the pulmonary arteries, inflammatory cell infiltration around alveoli and emboloic arteries,local hemorrhages in the alveoli and interstitial tissue could be found by microscopy. The lungs of control group were normal.3. The concentration of TNFa in blood: In PTE group there was very significant statistical differences between before and after PTE(P<0.01): After PTE, it began to go up at 30min, then rapidly elevated on 1th day and 3th day and peaking at 6th day, but went down on 9th day. In control group there was no significant difference (P>0.05). Comparisions between groups: there was statistical significantce on point, before PTE, after PTE 30min, 1 hour, 9th day.4.The level of IL-6 in blood: In PTE group there was very significant statistical differences between before and after PTE(P<0.01): After PTE, it began to go up at 30min, then gradually elevatedand remained higher level till 6th day, but went down on 9th day. In control group there was no significant difference (P>0.05). Comparisions between groups: there was statistical significantce on point, before PTE, after PTE 30min, 1 hour,2 hour, 1 th day,9th day.Conclusions 1. It has scientificity and feasibility to establish pulmonary thromboemoblism model of rabbits with injection of autologous blood clots.2. After acute PTE the concentration of IL-6 in blood remains higher , which promote the state of hypercoagulability of blood , and involves in the inflammatory response . Its inhibition may be a new kind treatment drugs of pulmonary thromboembolism.3. After acute PTE the concentration of TNF a in blood remains higher, which involves in the inflammatory response and secondary thrombosis after pulmonary thromboembolism and contributes to the pathophysiological alterations in connection with pulmonary thromboembolism. It may help doctors to provide prognosis clue and treatment measure of PTE.
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