Nossuli T O, Lakshminarayanan V, Baumgarten G, Taffet G E, Ballantyne C M, Michael L H, Entman M L
Section of Cardiovascular Sciences and Cardiology, Department of Medicine, DeBakey Heart Center, Baylor College of Medicine and Methodist Hospital, Houston, Texas 77030, USA.
Am J Physiol Heart Circ Physiol. 2000 Apr;278(4):H1049-55. doi: 10.1152/ajpheart.2000.278.4.H1049.
Reperfusion of the ischemic myocardium is associated with a cytokine cascade that reflects a cellular response to injury. We studied this cascade in the mouse and found that acute surgical trauma in sham-operated animals obscured early changes in cytokine induction that occur during myocardial ischemia-reperfusion (MI/R). Therefore, we utilized a new implantable device that allows occlusion and reperfusion of the left anterior descending coronary artery in a closed-chest mouse at any time after instrumentation. Induction of interleukin (IL)-6 and tumor necrosis factor (TNF)-alpha mRNA in the whole heart was examined by RNase protection assay and quantitated by Phosphor- Imager. At 3 h after instrumentation, levels of IL-6 mRNA in sham-operated animals increased above those of control naive hearts, whereas this increase did not occur until after 1 day for TNF-alpha mRNA. The surgical trauma led to exaggeration of I/R cytokine induction with greater variance in response. At 3 days and 1 wk after instrumentation, levels of both IL-6 and TNF-alpha mRNA in sham-operated animals were comparable to those of naive hearts and induction responses in I/R were much less variant. We also found that 1 h of ischemia and 2 h of reperfusion at all time points of recovery (i.e., 3 h and 1, 3, and 7 days after instrumentation) led to a significant increase in IL-6 and TNF-alpha mRNA levels. In addition, 3 h of permanent occlusion, which did not induce any mRNA increase after 1 wk postinstrumentation, caused marked upregulation of IL-6 mRNA in an acutely prepared animal. This study of early cytokine responses evoked by MI/R highlights the need for dissipation of acute surgical trauma by using a chronic, closed-chest mouse preparation.
缺血心肌的再灌注与反映细胞对损伤反应的细胞因子级联反应相关。我们在小鼠中研究了这种级联反应，发现假手术动物的急性手术创伤掩盖了心肌缺血再灌注（MI/R）期间发生的细胞因子诱导的早期变化。因此，我们使用了一种新的可植入装置，该装置可在仪器植入后的任何时间对闭胸小鼠的左前降支冠状动脉进行闭塞和再灌注。通过核糖核酸酶保护试验检测全心脏中白细胞介素（IL）-6和肿瘤坏死因子（TNF）-α mRNA的诱导情况，并通过磷光成像仪进行定量分析。在仪器植入后3小时，假手术动物的IL-6 mRNA水平高于未处理的对照心脏，而TNF-α mRNA直到1天后才出现这种升高。手术创伤导致I/R细胞因子诱导的夸大，反应差异更大。在仪器植入后3天和1周，假手术动物的IL-6和TNF-α mRNA水平与未处理的心脏相当，I/R中的诱导反应变化小得多。我们还发现，在恢复的所有时间点（即仪器植入后3小时和1、3、7天），1小时的缺血和2小时的再灌注导致IL-6和TNF-α mRNA水平显著升高。此外，在急性制备的动物中，3小时的永久性闭塞在仪器植入后1周未引起任何mRNA增加，但导致IL-6 mRNA显著上调。这项对MI/R诱发的早期细胞因子反应的研究强调了使用慢性闭胸小鼠制备方法来消除急性手术创伤的必要性。
