|
Background and purpose: To date, lung ischemia - reperfusion injury (Lung Ischemia Reperfusion Injury, LIRI) is the Cardiothoracic surgeon facing serious challenges. LIRI often occurs in a variety of clinical cases of heart surgery, lung transplantation or heart and lung transplantation, pulmonary embolism and shock during cardiopulmonary bypass, especially in the process of lung transplantation, can cause severe acute respiratory distress syndrome, multiple organ dysfunction. Ischemia - reperfusion induced lung injury is characterized by nonspecific alveolar damage, pulmonary edema and hypoxemia. Lung transplant ischemia - reperfusion transplant lung injury caused by high morbidity and mortality, it is necessary to better understand the mechanism of LIRI, and find more effective measures to reduce reperfusion injury. Ischemic postconditioning (Ischemic Postconditioning, I PostC) A reperfusion the initial intermittent prefilled in the myocardium and liver has been shown to reduce ischemia - reperfusion injury. In this study, established on the basis of preliminary studies rat pulmonary ischemia - reperfusion model application after treatment intervention by their expression of SP-A in the detection of lung tissue and NO level to explore post-processing, analysis of post-treatment measures on lung ischemia - reperfusion injury protection mechanisms, to provide a theoretical basis for clinical application. Materials and Methods: 80 healthy male SD rats, 30g / L intraperitoneal injection of sodium pentobarbital (30mg/kg) anesthesia, tracheotomy after intubation connected the TKP-200C animals ventilator control breathing respiratory rate of 60 beats / min, inspiratory to expiratory ratio of 1:1.5, working pressure (tidal volume): 0.02MPa. Into the chest through left fifth intercostal space, free of the left hilar, after blocking with end sets of rubber tube forming the slipknot equipment shutoff. Before surgery by the dorsal penile intravenous heparin sodium 100U/kg to maintain heparinization. every 1h by subcutaneous injection saline 1.5ml/kg, to replenish moisture lost during reperfusion, animals were randomly divided into five groups, each group of 8 - sham group (C group): the completion of the above operative, but the hilar not blocking; ischemia - reperfusion group (IR), is divided into two periods, namely 45min after ischemia reperfusion 45min group (IR45) and reperfusion 120min (IR120); ischemic postconditioning group (P group), also divided into two periods, 45min after ischemia reperfusion 45min group (P45) and reperfusion 120min (P120), in this group, transient reperfusion after ischemia 45min 1min, ischemic 1min repeatedly 5 times, and then the full restoration of perfusion. After the end of the experiment, the rats were killed, cut fresh left lung tissue blocks, with 40g / L paraformaldehyde fixed, paraffin embedded sections using immunohistochemical methods Determination of SP-A in the lung tissue and eNOS expression levels; under the light microscope HE staining pathomorphology. 40 healthy male SD rats were randomly divided into above five groups to determine NO content and NOS, iNOS activity. Results: 1. Changes in the expression levels of SP-A in the lung tissue: cytoplasm appeared brown positive staining lung tissue after ischemia - reperfusion, IR group compared with the C group, the level of expression of SP-A decreased significantly (P lt; 0.01), and a downward trend over time; P group with the corresponding period of IR group compared expression levels were significantly increased (P lt; 0.01). 2. Lung tissue eNOS expression level changes: the cytoplasm appeared brown positive staining of lung tissue after ischemia - reperfusion, IR group compared with the C group, the level of eNOS expression was significantly decreased (P lt; 0.01 ), and as time goes on a downward trend; P group compared with the corresponding period of the IR group, the expression levels were significantly increased (P lt; 0.01). NO content and NOS in the lung tissue, iNOS activity was measured: lung tissue after ischemia - reperfusion, IR group compared with the C group, lung tissue NO content was significantly higher (P lt; 0.01), NOS and iNOS activity was significantly higher (P lt; 0.01), and they have tended to increase over time; P group and compared to the corresponding period of the IR group, NO content in the lung tissue was significantly decreased (P lt; 0.01), NOS iNOS activity was significantly decreased (P lt; 0.01). Pathological changes of the lung tissue: C group: the alveolar walls of the lung tissue thin, clear structure, approximate normal lung tissue; IR group: the alveolar septa inflammatory cell infiltration, edema, alveolar space inflammatory cells and fluid leakage, fuzzy alveolar structure The above change with time and aggravation; P group compared to the corresponding period of the IR group, the changes were significantly reduced. Conclusion: (1) I postC by increased expression of SP-A and eNOS reduce LIRI. (2) I postC through a decrease of the content of NO and reduce the activity of the NOS, iNOS, reduce LIRI. (3) I postC resume after the completion of the surgery or ischemia comprehensive blood perfusion immediately before placing the method is simple, calm time, undoubtedly much more ischemic preconditioning has direct clinical value.
|