Aebert H, Cornelius T, Ehr T, Holmer S R, Birnbaum D E, Riegger G A, Schunkert H
Department of Thoracic and Cardiovascular Surgery, University Hospital, Regensburg, Germany.
Ann Thorac Surg. 1997 Jun;63(6):1669-75. doi: 10.1016/s0003-4975(97)00272-5.
Induction of protooncogenes such as c-fos, c-jun, and EGR-1 has been implicated in cellular growth and differentiation. Heat-shock proteins (HSPs) such as hsp 70 may mediate resistance to ischemia after heat shock and ischemic preconditioning. The effects of cardioplegia on the regulation of these immediate early genes are unclear.
Isolated rat hearts were subjected to different cold (5 degrees C) or normothermic (35 degrees C) cardioplegic solutions and reperfused with normothermic Krebs-Henseleit buffer. Right atrial biopsy specimens from patients undergoing coronary artery bypass grafting with cold cardioplegic arrest were taken before and after cardiopulmonary bypass. Analysis of immediate early gene messenger RNAs was performed using Northern blots. Related proteins were localized by immunohistochemistry.
In rat hearts, cold cardioplegia for 40 minutes with Bretschneider or St. Thomas' II solution followed by 40 minutes' reperfusion resulted in a significant increase in left ventricular c-fos, EGR-1, and c-jun messenger RNA levels (4.0-, 3.1-, and 3.0-fold, respectively, with Bretschneider solution and 3.7-, 2.8-, and 2.1-fold, respectively, with St. Thomas' II solution) compared with control hearts perfused at 35 degrees C with Krebs-Henseleit buffer. Normothermic cardioplegia with St. Thomas' II solution was without effect, whereas sequential perfusion with Krebs-Henseleit buffer at 5 degrees C and 35 degrees C resulted in a similar increase in protooncogene messenger RNA levels. Only cold Bretschneider solution was related to a 5.2-fold induction of hsp 70 messenger RNA levels. Likewise, rat atrial tissues and samples from patients after cardiopulmonary bypass displayed a significant induction of these immediate early genes. Monoclonal antibodies against c-FOS and HSP 70 proteins stained nuclei and perinuclear spaces of endothelial cells and cardiac myocytes.
Cold cardioplegic arrest and normothermic reperfusion are potent triggers for immediate early gene induction. Hypothermia emerged as the prime stimulus for the examined protooncogenes. In contrast, hsp 70 induction was dependent on the cardioplegic solution.
原癌基因如c-fos、c-jun和EGR-1的诱导与细胞生长和分化有关。热休克蛋白（HSPs）如hsp 70可能介导热休克和缺血预处理后对缺血的抵抗。心脏停搏液对这些即刻早期基因调控的影响尚不清楚。
将离体大鼠心脏置于不同的冷（5℃）或常温（35℃）心脏停搏液中，并在常温的克雷布斯-亨泽莱特缓冲液中再灌注。对接受冠状动脉搭桥术并采用冷心脏停搏的患者，在体外循环前后取右心房活检标本。使用Northern印迹法分析即刻早期基因信使核糖核酸。相关蛋白通过免疫组织化学进行定位。
在大鼠心脏中，用布雷施奈德或圣托马斯II号溶液进行40分钟的冷心脏停搏，随后再灌注40分钟，与在35℃用克雷布斯-亨泽莱特缓冲液灌注的对照心脏相比，左心室c-fos、EGR-1和c-jun信使核糖核酸水平显著升高（布雷施奈德溶液分别升高4.0倍、3.1倍和3.0倍，圣托马斯II号溶液分别升高3.7倍、2.8倍和2.1倍）。用圣托马斯II号溶液进行常温心脏停搏无影响，而在5℃和3℃依次用克雷布斯-亨泽莱特缓冲液灌注导致原癌基因信使核糖核酸水平有类似升高。只有冷布雷施奈德溶液与hsp 70信使核糖核酸水平升高5.2倍有关。同样，大鼠心房组织和体外循环后患者的样本显示这些即刻早期基因有显著诱导。针对c-FOS和HSP 70蛋白的单克隆抗体对内皮细胞和心肌细胞的细胞核及核周间隙进行染色。
冷心脏停搏和常温再灌注是即刻早期基因诱导的有效触发因素。低温是所检测原癌基因的主要刺激因素。相比之下，hsp 70的诱导取决于心脏停搏液。
