| Background and purposes: Pulmonary thromboembolism(PTE) was ever considered as a rare disease, and in a great extent resulted in ignoring to identify and diagnose it in medical society in China , however, PTE is not rare .In recent years , data from some hospitals of China show that morbidity rate and proportional morbidity rate of PTE have an increasing trend .Clinical presentations of PTE are so complicated and variable that it is often misdiagnosed . PTE has a broad spectrum of manifestations from minimal disease to sudden death. Clinical presentations of PTE lack specificity .About 67% of PTE unsuspected were confirmed in autopsy series and about 18%~39% patients with PTE were diagnosed before demise. In addition, mortality rate of PTE is high, and according to epidemiological data, PTE is estimated to the third most cause of death in the United States. Mortality of PTE is approximately 25%~30% if it is not treated, conversely, mortality reduces to <10% if diagnosed and treated correctly. PTE is a common and potentially life-threatening disorder, moreover, there has been no significant reduction in mortality of PTE over past 40 years. So it is urgent to prevent and treat PTE effectively in current medical research .After PTE , on one hand, functions of respiratory and cardiovascular systems are affected due to mechanical obstruction, on the other hand, lots of physiological functions and metabolisms are changed due to factors associated with nerve and body fluid . At early stage of PTE, perhaps the latter is more important. When thrombus is translocated by blood stream, vascular endothelia and platelets are activated. Activated platelets release granules, and then both levels ofendothelin-l(ET-l) and P-selectin(Ps) are raised .ET-1 may induce vasoconstriction and bronchoconstriction , moreover, promote various cells to secrete and proliferate . Lung is not only targeted organ of ET-1, but also a place of synthesis, secretion and metabolism of ET-1. Sofia proved that that metabolism of ET-1 was not normal by monitoring plasma levels of ET-1 after PTE. Ps is stored in a-granules of platelets and Weibel-Palade bodies of endothelial cells . Increased Ps levels may contribute to secondary thrombosis, and then aggravates PTE. The purpose of this study is to investigate the significance of ET-1 and Ps in the mechanism of PTE by monitoring the plasma levels of ET-1 and Ps in rabbits with PTE.Materials and methods: Thirty rabbits were randomed to either PTE group (n=15) or control group (n=15). PTE model of rabbits were established with injection of autologous blood clots stabilized in a temperature-controlled (70癈) of distilled water for ten minutes through the femoral vein . 4ml blood was collected from ears' vein of rabbits periodically , and 2 ml of 4 ml blood was put into the tube with 10% EDTANa2 30 ml and bestatin 40ul , and 1.8 ml was placed into the tube with 2% EDTANa2 0.2 ml .Under temperature 4癈 , blood samples were discentered for ten minutes at 3000 rounds/minutes , and then was stored in temperature -80'C in refrigerator . The PTE models of rabbits were explored at dissection and upon microscopical examination after they were killed . The plasma levels of ET-1 were measured by radioimmunoassay and the plasma tevels of Ps were examined by ELISA . Statistical analysis was analysed with software SPSS 10.0 using T-test and analysis of variance of repeated measurement. P value < 0.05 is considered as statistically significant.Results: 1. Changes of ET-1 levels.(1) Self comparisons: The plasma levels of ET-1 in the third, fifth, seventh and tenth day are significantly higher than before PTE in the PTE group, respectively P<0.05, and there are significant statistical differences.(2) Comparisons between groups: The plasma levels of ET-1 are significantly higher in PTE group in the third, fifth, seventh day and tenth day than in control group in the corresponding day, and P<0.05, respectively. And there are significant statistical differences.2. Changes of P-selectin levels(1) Self comparisons:... |
