Zhang Wei-Hua, Lu Fang-Hao, Zhao Ya-Jun, Wang Li-Na, Tian Ye, Pan Zhen-Wei, Lv Yan-Jie, Wang Yan-Li, Du Li-Juan, Sun Zhi-Rui, Yang Bao-Feng, Wang Rui, Xu Chang-Qing
Department of Pathophysiology, Harbin Medical University, Harbin 150086, China.
Biochem Biophys Res Commun. 2007 Sep 28;361(3):659-64. doi: 10.1016/j.bbrc.2007.07.077. Epub 2007 Jul 24.
Protein kinase C (PKC) plays a role in cardioprotection through reduction of intracellular Ca(2+) concentration Ca(2+) during ischemic preconditioning (IPC). Cardioprotection against ischemic post-conditioning (PC) could be associated with reduced Ca(2+) through PKC. The calcium-sensing receptor (CaR), G protein-coupled receptor, causes accumulation of inositol phosphate (IP) to increase the release of intracellular Ca(2+). However, this phenomenon can be negatively regulated by PKC through phosphorylation of Thr-888 of the CaR. This study tested the hypothesis that the prevention of cardiomyocyte damage by PC is associated with Ca(2+) reduction through an interaction of PKC with the CaR. Isolated rat hearts were subjected to 40min of ischemia followed by 90min of reperfusion. The hearts were post-conditioned after the 40min of ischemia by three cycles of 30s of reperfusion and 30s of re-ischemia applied before the 90min of reperfusion. Immunolocalization of PKCepsilon in the cell membrane was observed with IPC and PC, and in hearts exposed to GdCl(3) during PC. CaR was expressed in cardiac cell membrane and interacted with PKC in IPC, PC, and exposure to GdCl(3) during PC groups. On laser confocal microscopy, intracellular Ca(2+) was significantly decreased with IPC, PC, and exposure to GdCl(3) during PC compared with the I/R and PKC inhibitor groups, and cell structure was better preserved and promoted the recovery of cardiac function after reperfusion in the same groups. These results suggested that PKC is involved in cardioprotection against PC through negative feedback of a CaR-mediated reduction in Ca(2+).
蛋白激酶C（PKC）在缺血预处理（IPC）期间通过降低细胞内Ca²⁺浓度[Ca²⁺]i发挥心脏保护作用。对缺血后处理（PC）的心脏保护可能与PKC介导的[Ca²⁺]i降低有关。钙敏感受体（CaR）是一种G蛋白偶联受体，可导致肌醇磷酸（IP）积累，从而增加细胞内Ca²⁺释放。然而，这种现象可被PKC通过对CaR的苏氨酸-888磷酸化进行负调控。本研究检验了以下假设：PC对心肌细胞损伤的预防与PKC与CaR相互作用导致的[Ca²⁺]i降低有关。将离体大鼠心脏进行40分钟缺血，然后再灌注90分钟。在40分钟缺血后，通过在90分钟再灌注前进行三个30秒再灌注和30秒再缺血的循环对心脏进行后处理。在IPC和PC以及PC期间暴露于GdCl₃的心脏中观察到PKCε在细胞膜中的免疫定位。CaR在心肌细胞膜中表达，并在IPC、PC以及PC期间暴露于GdCl₃的组中与PKC相互作用。在激光共聚焦显微镜下，与缺血/再灌注和PKC抑制剂组相比，IPC、PC以及PC期间暴露于GdCl₃时细胞内Ca²⁺显著降低，并且相同组中细胞结构得到更好的保存，促进了再灌注后心脏功能的恢复。这些结果表明，PKC通过CaR介导的[Ca²⁺]i降低的负反馈参与对PC的心脏保护。
