Zeevi-Levin Naama, Barac Yaron D, Reisner Yotam, Reiter Irina, Yaniv Gal, Meiry Gideon, Abassi Zaid, Kostin Sawa, Schaper Jutta, Rosen Michael R, Resnick Nitzan, Binah Ofer
Rappaport Faculty of Medicine, Technion, Haifa, Israel.
Cardiovasc Res. 2005 Apr 1;66(1):64-73. doi: 10.1016/j.cardiores.2005.01.014.
Altered gap junctional coupling of ventricular myocytes plays an important role in arrhythmogenesis in ischemic heart disease. Since hypoxia is a major component of ischemia, we tested the hypothesis that hypoxia causes gap junctional remodeling accompanied by conduction disturbances.
Cultured neonatal rat ventricular myocytes were exposed to hypoxia (1% O(2)) for 15 min to 5 h, connexin43 (Cx43) expression was analyzed, and conduction velocity was measured using the Micro-Electrode Array data acquisition system.
After 15 min of hypoxia, conduction velocity was unaffected, while total Cx43, including the phosphorylated and nonphosphorylated isoforms, was increased. After 5 h of hypoxia, total Cx43 protein was decreased by 50%, while the nonphosphorylated Cx43 isoform was unchanged. Confocal analyses yielded a 55% decrease in the gap junctional Cx43 fluorescence signal, a 55% decrease in gap junction number, and a 26% decrease in size. The changes in Cx43 were not accompanied by changes in mRNA levels. The reduction in Cx43 protein levels was associated with a approximately 20% decrease in conduction velocity compared to normoxic cultures.
Short-term hypoxia (5 h) decreases Cx43 protein and conduction velocity, thereby contributing to the generation of an arrhythmogenic substrate.
心室肌细胞间隙连接偶联的改变在缺血性心脏病的心律失常发生中起重要作用。由于缺氧是缺血的主要组成部分，我们检验了以下假说：缺氧会导致间隙连接重塑并伴有传导障碍。
将培养的新生大鼠心室肌细胞暴露于缺氧环境（1% O₂）15分钟至5小时，分析连接蛋白43（Cx43）的表达，并使用微电极阵列数据采集系统测量传导速度。
缺氧15分钟后，传导速度未受影响，而包括磷酸化和非磷酸化异构体在内的总Cx43增加。缺氧5小时后，总Cx43蛋白减少50%，而非磷酸化Cx43异构体未变。共聚焦分析显示间隙连接Cx43荧光信号减少55%，间隙连接数量减少55%，大小减少26%。Cx43的变化未伴随mRNA水平的改变。与常氧培养相比，Cx43蛋白水平的降低与传导速度降低约20%相关。
短期缺氧（5小时）会降低Cx43蛋白和传导速度，从而导致致心律失常基质的产生。
