Waldow Thomas, Witt Wolfgang, Ulmer André, Janke Andreas, Alexiou Konstantin, Matschke Klaus
Clinic for Cardiac Surgery, University Hospital Dresden, Fetscherstr. 76, 01307 Dresden, Germany.
Pulm Pharmacol Ther. 2008;21(2):418-29. doi: 10.1016/j.pupt.2007.10.005.
Since the generation of nitric oxide (NO) is an essential step in the trigger phase of ischemic preconditioning, short-term inhalation of NO before ischemia should ameliorate ischemia/reperfusion (I/R) injury of the lung. We tested this hypothesis in high oxygen (>99%) ventilated rats in order to additionally evaluate compatibility of NO and exposure to hyperoxia. Male adult Sprague-Dawley rats inhaled NO (15 ppm, 10 min) before the left lung hilum was clamped for 1 h, and the reperfusion phase was observed for 4 h (NO group). Animals in the I/R group underwent the same treatment, but without NO inhalation. A third group without I/R served as time-matched controls. Animals in the I/R group showed severe I/R injury in terms of arterial pO2 (apO2), which was reduced to 22% of surgical controls (SCs) at time point 30 min reperfusion, and increased endothelial permeability (Evans blue procedure). The pretreatment with NO attenuated these effects. The pO2 after 4 h reperfusion was still 3.0-fold higher in the NO group compared to I/R. In contrast, the I/R- and hyperoxia-induced invasion of leukocytes, as determined by measuring myeloperoxidase (MPO) activity, was not affected by NO. These data were correlated with the activity of major cellular signaling pathways by measuring the phosphorylation at activating and inhibitory sites of extracellular-signal regulated kinase (ERK), c-Jun N-terminal kinase (JNK), p38, protein kinase B (AKT), and glycogen synthase kinase 3beta (GSK-3beta), and by determination of cGMP in plasma and lung tissue. Inhalation of NO partly prevented the loss of activation by I/R and hyperoxic ventilation of ERK, JNK, and AKT, and it reduced the I/R-induced activation of GSK-3beta. The level of cGMP in plasma and lung tissue was increased in the NO group after 4 h reperfusion. In conclusion, application of inhaled NO in the preconditioning mode prevented I/R injury in the rat lung without interfering effects of hyperoxic ventilation. The effects of NO on cellular signaling pathways resemble mechanisms of ischemic preconditioning, but further studies have to evaluate the physiological relevance of these results.
由于一氧化氮（NO）的生成是缺血预处理触发阶段的关键步骤，缺血前短期吸入NO应能减轻肺的缺血/再灌注（I/R）损伤。我们在高氧（>99%）通气的大鼠中验证了这一假设，以额外评估NO与高氧暴露的兼容性。成年雄性Sprague-Dawley大鼠在左肺门夹闭1小时前吸入NO（15 ppm，10分钟），并观察4小时的再灌注阶段（NO组）。I/R组动物接受相同处理，但不吸入NO。第三组无I/R作为时间匹配对照。I/R组动物在动脉血氧分压（apO2）方面表现出严重的I/R损伤，在再灌注30分钟时降至手术对照（SCs）的22%，且内皮通透性增加（伊文思蓝法）。NO预处理减轻了这些影响。再灌注4小时后，NO组的pO2仍比I/R组高3.0倍。相反，通过测量髓过氧化物酶（MPO）活性确定的I/R和高氧诱导的白细胞浸润不受NO影响。这些数据通过测量细胞外信号调节激酶（ERK）、c-Jun氨基末端激酶（JNK）、p38、蛋白激酶B（AKT）和糖原合酶激酶3β（GSK-3β）激活和抑制位点的磷酸化，以及测定血浆和肺组织中的cGMP，与主要细胞信号通路的活性相关。吸入NO部分防止了I/R和高氧通气导致的ERK、JNK和AKT激活丧失，并降低了I/R诱导的GSK-3β激活。再灌注4小时后，NO组血浆和肺组织中的cGMP水平升高。总之，以预处理模式吸入NO可预防大鼠肺的I/R损伤，且无高氧通气的干扰作用。NO对细胞信号通路的影响类似于缺血预处理机制，但进一步研究必须评估这些结果的生理相关性。
