无搏动血流对肺微循环血管结构和功能的长期影响

目的探讨长期肺循环无搏动血流对肺微血管床结构和功能的影响，以明确在该血流灌注下是否存在肺血管重塑。方法建立犬右肺单侧无搏动血流灌注的动物模型，6个月后采用链亲和素-生物素-酶复合物法检测两侧肺组织血管内皮细胞内皮型一氧化氮合酶（endothelial nitric oxide synthase，eNOS）和肺动脉微平滑肌细胞fas的表达，在光学显微镜下观察两侧肺组织毛细血管床微小动脉结构的变化。结果无搏动血流灌注的右肺微小动脉eNOS表达积分值显著低于左肺（10846．7±177．8vs．13136．1±189．6；t=2．240，P=0．040）；右肺微动脉平滑肌细胞fas表达显著高于左肺（14254．1±217．1vs．11976．7±195．7；t=2．160，P=0．040）；肺微动脉图象分析显示，管壁厚度与血管外径比值（13．64％±12．80％vs．14．96％±13．10％）、管壁面积与血管总面积比值（46．40％±11．70％vs．47．80％±12．20％）显著小于左肺（P〈0．05）。结论长期无搏动血流灌注会引起肺血管内皮细胞eNOS合成减少，一方面导致肺泡真毛细血管网的前括约肌毛细血管收缩，肺小血管阻力升高，直捷通路及动静脉短路持续开放，引起低氧血症及活动耐力下降；另一方面导致微动脉血管壁平滑肌细胞凋亡增加，动脉静脉化。

The Long Effect of Nonpulsatile Flow on Changes of Structure and Function in Pulmonary Microcirculation

Objective To investigate the long effect of nonpulsatile flow on changes of structure and function in pulmonary microcirculation and to identify the pulmonary reconstruction under this blood perfusion. Methods Canine models with nonpulsatile flow in the right lung was established, and sacrificed 6 months later. Compare endothelial nitric oxide synthase （eNOS） in vascular endothelium, apoptosis in smooth muscle cell with immunohistochemistry by streptavidin-bioepiderm-muhienzyme complex methodes, and observe structural changes in pulmonary arterioles with optical microscope. Results The expression of eNOS in the right nonpulsatile flow perfusing lung was weaker as compared to the left lung （10 846.7±177.8 vs. 13 136. 1±189. 6;t=2.240, P= 0.040）, the fas was stronger as compared to the left lung（14 254. 1±217. 1 vs. 11 976. 7±195.7; t=2.160, P= 0. 040）. The ratio of wall thichness/vessel diameter in the right lung（13.64%±12.80% vs. 14.96%±13.10%） and wall area/vessel area（46.40%±11.70% vs. 47.80%±12.20%） was lower as compared to the left lung（P〈0. 05）. Conclusion Long-term nonpulsatile flow can decrease the expression of eNOS, contract the muscles in capillary net, and increase pulmonary vascular resistance. Moreover it can increase the arteriole apoptosis, leading to vascular structure remodeling.