Lin Jijin, Li Yuguang, Lin Shuguang, Liang Qing, Tan Xuerui
Department of Cardiology, Guangdong Provincial People's Hospital and Guangdong Cardiovascular Institute, 106 Zhongshan Er Road, Guangzhou 510080, China.
Biochem Cell Biol. 2007 Apr;85(2):175-81. doi: 10.1139/O07-003.
The objective of this study is to investigate the effects of preconditioning on the restoration and distribution of connexin 43 (Cx43) in ischemic myocardium in dogs. In this study, 40 dogs were randomly divided into 5 groups of 8 as follows: control, 0hI-R (ischemia followed by 0 h reperfusion), 6hI-R (ischemia followed by 6 h reperfusion), 24hI-R (ischemia followed by 24 h reperfusion), and 48hI-R (ischemia followed by 48 h reperfusion). Four dogs in each group were preconditioned with brief episodes of ischemia prior to the respective treatments and were referred as the PC groups, while the other 4 were not preconditioned and were referred as the nonPC groups. The myocardial ischemia was induced by ligation of the left anterior descending coronary artery. The expression and distribution of Cx43 within the ischemic myocardium were measured by Western blot analysis and studied using laser confocal microscopy using a double-label immunohistochemistry technique. Compared with the control group, there was a significant reduction in Cx43 content within ischemic myocardium of all test groups both with and without PC (P < 0.01, P < 0.05). Within the 0hI-R, 6hI-R, and 24hI-R groups, an insignificant difference was found in the expression and distribution of Cx43 within the ischemic region between the PC and the nonPC groups. However, in the 48hI-R group, the area and intensity of Cx43 staining within the ischemic region of the PC dogs were significantly larger and more intense than those of the nonPC dogs (P < 0.01), and the ratio of Cx43 pixel density in intercalated disk areas to that in side-to-side junction areas in the PC dogs was significantly greater than that in nonPC dogs (P < 0.01). Our results suggest that preconditioning has a significant effect on the restoration and distribution of Cx43 in the ischemic myocardium in dogs after 48 h. Hence, preconditioning may be a plausible cause for the observed reductions in cardiac arrhythmias.
本研究的目的是探讨预处理对犬缺血心肌中连接蛋白43（Cx43）恢复和分布的影响。在本研究中，40只犬被随机分为5组，每组8只，分组如下：对照组、0hI-R（缺血后0小时再灌注）、6hI-R（缺血后6小时再灌注）、24hI-R（缺血后24小时再灌注）和48hI-R（缺血后48小时再灌注）。每组中的4只犬在各自治疗前进行短暂缺血预处理，称为预处理组（PC组），另外4只未进行预处理，称为非预处理组（nonPC组）。通过结扎左冠状动脉前降支诱导心肌缺血。采用蛋白质免疫印迹分析法测定缺血心肌中Cx43的表达和分布，并使用激光共聚焦显微镜通过双标免疫组织化学技术进行研究。与对照组相比，所有进行和未进行预处理的试验组缺血心肌中的Cx43含量均显著降低（P<0.01，P<0.05）。在0hI-R、6hI-R和24hI-R组中，预处理组和非预处理组缺血区域内Cx43的表达和分布无显著差异。然而，在48hI-R组中，预处理犬缺血区域内Cx43染色的面积和强度显著大于非预处理犬（P<0.01），预处理犬闰盘区域Cx43像素密度与侧向连接区域Cx43像素密度之比显著高于非预处理犬（P<0.01）。我们的结果表明，预处理对犬缺血心肌48小时后Cx43的恢复和分布有显著影响。因此，预处理可能是观察到心律失常减少的一个合理原因。
