Department of Cardiology, The First Affiliated Hospital of Harbin Medical University, Harbin, China.
Mol Cell Biochem. 2012 Feb;361(1-2):123-34. doi: 10.1007/s11010-011-1096-7. Epub 2011 Oct 5.
Our previous studies demonstrated that caclium-sensing receptor (CaR) stimulation elicited phospholipase C (PLC)-mediated inositol triphosphate (IP(3)) formation, leading to an elevation in Ca(2+) released from the endo(sarco)plasmic reticulum (ER) to induce ER stress and perturbations of ER function, which cause cardiomyocyte apoptosis during ischemia/reperfusion (I/R). The aim of this study was to determine whether the protection of post-conditioning (PC) from I/R heart injury involved relieving calcium-sensing receptor (CaR)-induced ER stress. Male Wistar rats were subjected to 30 min of ischemia followed by 2 h of reperfusion. The rats were post-conditioned after the 30 min of ischemia by three cycles of 10 s of reperfusion followed by 10 s of ischemia at the onset of reperfusion. Meanwhile, GdCl(3), an activator of CaR, and NPS-2390, a specific inhibitor, were administered. We found that the PC and PC with NPS-2390 groups improved the recovery of cardiac function during reperfusion compared to the IR and PC groups with GdCl(3), respectively. Ca(2+) and Ca(2+) were determined using Fluo-4 AM and Fluo-5N AM, respectively, using laser confocal microscopy. Ca(2+) was significantly increased, whereas Ca(2+) was significantly decreased in the I/R and PC groups with GdCl(3). The rate of apoptotic cells was significantly decreased as shown by TUNEL (Terminal deoxy-nucleotidyl transferase-mediated dUTP nick end labeling) assay in PC and PC with NPS-2390 groups compared to the I/R and PC groups with GdCl(3). In the I/R and PC groups with GdCl(3), the activated fragments of caspase-12, the cleavage products of activating transcription factor 6 (ATF6) and phospho-JNK (c-Jun NH(2)-terminal kinase) were increased compared to the PC and PC with GdCl(3) groups. These results demonstrated that PC could protect the myocardium from I/R injury by inhibiting CaR-induced sarcoplasmic reticulum stress.
我们之前的研究表明，钙敏感受体（CaR）的刺激引发了磷脂酶 C（PLC）介导的三磷酸肌醇（IP3）形成，导致内质网（ER）中钙离子的释放增加，从而引发内质网应激和 ER 功能紊乱，这导致缺血/再灌注（I/R）期间心肌细胞凋亡。本研究旨在确定后适应（PC）是否从 I/R 心脏损伤中涉及缓解钙敏感受体（CaR）诱导的内质网应激。雄性 Wistar 大鼠进行 30 分钟缺血，随后进行 2 小时再灌注。大鼠在再灌注开始时，通过 3 个 10 秒的再灌注和 10 秒的缺血的循环进行后适应。同时，给予 GdCl3（CaR 的激活剂）和 NPS-2390（特异性抑制剂）。我们发现，与 I/R 和 PC+GdCl3 组相比，PC 和 PC+NPS-2390 组在再灌注期间改善了心脏功能的恢复。使用激光共聚焦显微镜分别使用 Fluo-4 AM 和 Fluo-5N AM 测定[Ca2+]（i）和[Ca2+]（ER）。I/R 和 PC+GdCl3 组[Ca2+]（i）明显增加，而[Ca2+]（ER）明显降低。TUNEL（末端脱氧核苷酸转移酶介导的 dUTP 缺口末端标记）检测显示，与 I/R 和 PC+GdCl3 组相比，PC 和 PC+NPS-2390 组的凋亡细胞比例明显降低。与 PC+GdCl3 组相比，I/R 和 PC+GdCl3 组的半胱氨酸天冬氨酸蛋白酶-12 的激活片段、激活转录因子 6（ATF6）和磷酸化-JNK（c-Jun NH2-末端激酶）的裂解产物增加。这些结果表明，PC 可以通过抑制 CaR 诱导的肌浆网应激来保护心肌免受 I/R 损伤。
