Zhang Li, Kumar Sanjeev, Kaminski Alexander, Kasch Cornelius, Sponholz Christoph, Stamm Christof, Ladilov Yury, Steinhoff Gustav
Department of Cardiac Surgery, University of Rostock, Rostock, Germany.
J Thorac Cardiovasc Surg. 2006 May;131(5):969-74. doi: 10.1016/j.jtcvs.2005.12.033.
The hypothesis that the protective effects of mild hypothermia against the pulmonary ischemia-reperfusion injury are mediated by endothelial nitric oxide synthase was tested.
Endothelial nitric oxide synthase knock-out and wild-type mice were sham operated or underwent a 1-hour occlusion of the left pulmonary hilum, followed by 5 hours of reperfusion. Temperature in the left pleural cavity during ischemia was maintained at either 36 degrees C (normothermia) or 32 degrees C (hypothermia). Inflammatory response (myeloperoxidase activity), endothelial barrier function (extravasation of Evans blue-labeled albumin), and endothelial nitric oxide synthase expression and phosphorylation were determined at the end of reperfusion.
After normothermic ischemia both strains had a similar mortality (wild-type, 22.9%; knock-out, 15.4%), which was completely abolished by hypothermia. Endothelial barrier function was disturbed after normothermic ischemia in both wild-type and knock-out mice. Mild hypothermia significantly reduced pulmonary Evans blue extravasation in wild-type mice, but not in knock-out mice. Myeloperoxidase activity increased after normothermic ischemia to the same degree in both strains. This response was significantly attenuated by hypothermia in wild-type mice, but not in knock-out mice. In wild-type mice, endothelial nitric oxide synthase expression and phosphorylation were higher after hypothermic ischemia than after normothermic ischemia. No effect of ischemia on expression of inducible nitric oxide synthase was found in wild-type or knock-out mice.
Hypothermic protection against pulmonary ischemia-reperfusion injury is dependent on endothelial nitric oxide synthase and is associated with increased expression and phosphorylation of endothelial nitric oxide synthase.
验证轻度低温对肺缺血-再灌注损伤的保护作用是由内皮型一氧化氮合酶介导的这一假说。
对内皮型一氧化氮合酶基因敲除小鼠和野生型小鼠进行假手术，或对左肺门进行1小时阻断，随后进行5小时再灌注。缺血期间左胸腔温度维持在36℃（正常体温）或32℃（低温）。在再灌注结束时测定炎症反应（髓过氧化物酶活性）、内皮屏障功能（伊文思蓝标记白蛋白的渗出）以及内皮型一氧化氮合酶的表达和磷酸化。
常温缺血后，两种品系的死亡率相似（野生型为22.9%，基因敲除型为15.4%），低温可完全消除这种死亡率。野生型和基因敲除型小鼠在常温缺血后内皮屏障功能均受到干扰。轻度低温显著降低了野生型小鼠肺伊文思蓝的渗出，但对基因敲除型小鼠没有影响。常温缺血后，两种品系的髓过氧化物酶活性均升高到相同程度。这种反应在野生型小鼠中被低温显著减弱，但在基因敲除型小鼠中没有。在野生型小鼠中，低温缺血后内皮型一氧化氮合酶的表达和磷酸化高于常温缺血后。在野生型或基因敲除型小鼠中未发现缺血对诱导型一氧化氮合酶表达有影响。
低温对肺缺血-再灌注损伤的保护作用依赖于内皮型一氧化氮合酶，且与内皮型一氧化氮合酶表达和磷酸化增加有关。
