Sumeray M S, Rees D D, Yellon D M
The Hatter Institute, Department of Academic and Clinical Cardiology, University College Hospital, Grafton Way, London, WC1E 6DB, UK.
J Mol Cell Cardiol. 2000 Jan;32(1):35-42. doi: 10.1006/jmcc.1999.1050.
Controversy surrounds the involvement of nitric oxide (NO) in myocardial ischaemia-reperfusion injury and the balance between deleterious and beneficial effects. NO synthase (NOS) is expressed constitutively as two isoforms: endothelial (eNOS) and neuronal (nNOS). Knockout mice lacking the gene for either eNOS (eNOS KO) or nNOS (nNOS KO), were compared with wild-types (WT) during a protocol of global ischaemia-reperfusion injury. Thirty-six mouse hearts (12 from each group) were isolated and the aorta cannulated for Langendorff perfusion with modified Krebs solution at constant pressure. An apical suture connected the left ventricle to a force transducer via a light weight coupling rod. Following stabilization hearts were subjected to 30 min of global ischaemia at 37 degrees C. During 30 min reperfusion, the recovery of baseline force-rate product (F%) was recorded. Hearts were then stained with tetrazolium, frozen, sliced, and fixed with formalin. Slices were compressed between plexiglas plates, and a magnified video image digitized to allow planimetry for infarct size (as percentage of ventricular volume I/R). Although recovery of contractile function did not differ between groups, eNOS KOs suffered significantly larger infarcts than WT or nNOS KOs (41 v 33 and 30% respectively, P<0.05 for both comparisons). A protective role for eNOS against global ischaemia-reperfusion injury has been demonstrated for the first time in murine myocardium. This may have important clinical implications for future pharmacotherapy to enhance myocardial protection.
一氧化氮（NO）在心肌缺血再灌注损伤中的作用以及有害和有益作用之间的平衡存在争议。一氧化氮合酶（NOS）以两种亚型组成性表达：内皮型（eNOS）和神经型（nNOS）。在全脑缺血再灌注损伤实验中，将缺乏eNOS基因（eNOS基因敲除小鼠，eNOS KO）或nNOS基因（nNOS基因敲除小鼠，nNOS KO）的基因敲除小鼠与野生型小鼠（WT）进行比较。分离出36只小鼠心脏（每组12只），通过主动脉插管进行Langendorff灌注，用改良的Krebs溶液恒压灌注。通过轻质连接杆将心尖缝线连接到左心室与力传感器上。稳定后，心脏在37℃下进行30分钟的全脑缺血。在30分钟的再灌注过程中，记录基线力-率乘积（F%）的恢复情况。然后将心脏用四氮唑染色，冷冻，切片，并用福尔马林固定。切片在有机玻璃板之间压缩，将放大的视频图像数字化，以便进行梗死面积的平面测量（作为心室体积I/R的百分比）。虽然各组之间收缩功能的恢复没有差异，但eNOS基因敲除小鼠的梗死面积明显大于野生型或nNOS基因敲除小鼠（分别为41%、33%和30%，两组比较P<0.05）。首次在小鼠心肌中证实了eNOS对全脑缺血再灌注损伤具有保护作用。这可能对未来增强心肌保护的药物治疗具有重要的临床意义。
