Post-conditioning protecting rat cardiomyocytes from apoptosis via attenuating calcium-sensing receptor-induced endo(sarco)plasmic reticulum stress

Abstract

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+)](i) 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+)](i) and [Ca(2+)](ER) were determined using Fluo-4 AM and Fluo-5N AM, respectively, using laser confocal microscopy. [Ca(2+)](i) was significantly increased, whereas [Ca(2+)](ER) 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.

Neuregulin‐1 protects myocardial cells against H2O2‐induced apoptosis by regulating endoplasmic reticulum stress

“…The digested cells were neutralized by the addition of DMEM medium containing 10% fetal bovine serum. NRCMs were separated by differential attachment and cultured at a density of 500 cells per mm 2 . At 24 h of culture, cellular attachment and individual cell beating were observed, while monolayer myocardial cells and synchronous pulsation of cell clusters were observed at 48 h of culture.…”

“…Interestingly, endoplasmic reticulum (ER) stress has been shown to induce cardiomyocyte apoptosis during ischemia/reperfusion . During protein synthesis, 25% of cellular reactive oxygen species (ROS) such as H 2 O 2 are produced in the ER resulting from the activity of oxidoreductases, a family of proteins that catalyse protein folding .…”

“…Interestingly, endoplasmic reticulum (ER) stress has been shown to induce cardiomyocyte apoptosis during ischemia/reperfusion. 5 During protein synthesis, 25% of cellular reactive oxygen species (ROS) such as H 2 O 2 are produced in the ER resulting from the activity of oxidoreductases, a family of proteins that catalyse protein folding. 6 Unfortunately, ROS formation as a result of oxidoreductase activity is not exclusively linked to protein folding; excessive ROS would lead to oxidative stress and cause damage to a variety of molecules such as proteins, lipid and nucleic acids.…”

Discrepancy in calcium release from the sarcoplasmic reticulum and intracellular acidic stores for the protection of the heart against ischemia/reperfusion injury

“…Interestingly, stimulation of Ca 2+ release from the SR was demonstrated to be beneficial by conserving myocyte contractility [31]. Contradictory findings were demonstrated by postconditioning studies showing that blockade of Ca 2+ release from the SR is protective [18]. This controversy concerning the role of Ca 2+ release from SR contributes to the ambiguity regarding the role of Ca 2+ in postconditioning.…”

Ischemic postconditioning and pinacidil suppress calcium overload in anoxia-reoxygenation cardiomyocytes via down-regulation of the calcium-sensing receptor

“…It’s even reported that during cardiac I/R process, CaSR was over-expressed, which was involved in the calcium overload induced cardiomyocyte apoptosis (Zhang et al, 2006). Although CaSR activation during ischemic preconditioning may be myocardial protective in mice (Sun & Murphy, 2010), it has been well documented that IPC achieved myocardium protection partially by CaSR inhibition (Dong et al, 2010; Gan et al, 2012). …”