The Role Of The Micro-Cycle Sysyterm Dysfunction In Radiation-Induced Lung Injury

AIM To investigate the mechanisms of radiation-induced lung injury based on the microcirculation dysfunction performance including the changes of coagulation, anti-coagulation system and tissue hypoxia.METHODS AND MATERIALS Wistar 75 rats were irradiated to the right hemithorax with a single dose of OGy,7.OGy,14.4Gy. Serial studies were performed before and 1,7,30,90,180 days after irradiation. Histological studies were carried out to detect histological changes in the pulmonary after irradiation.immunohistochemistry assay was to detect the expression of TM, PAI-1, HIF-la.RESULTS In control group and 7.0Gy groups, there were no notable hispathological changes, just including little tissue exudates, congestion, edema and infiltration of inflammatory cells, red blood cell leakage. However, the inflammation was more obviously and the formation of collagen and fibrosis could be observed in 14.4Gy group.Compared with the control group, there was no difference of the expression of TM in 7.OGy group except lday.However, there was statistically significant in 14.4Gy group except 7 days. The expession of PAI-1 were difference in 7.0Gy group before 90days. Otherwise, there was statistically significant in 14.4Gy group at all time points. The expression of HIF-la was negative or weak positive in control and 7.OGy group.The expression of HIF-la had statistical significance atl,90,180 days after radiation, and also it was increased after 90 days.CONCLUSION Firstly the coagulation and anti-coagulation system changes persistently after radiation which was primary factor of radiation firbrosis. Secondly,tissue hypoxia may be no an important factor in the process of pulmonary fibrosis, it maybe the result of the later peride of radiation-induced lung injury. Thirdly when more than "threshold" dose of radiation, the microcirculation dysfunction was the main mechanism of radiation-induced lung injury.