The Effect Of Endoplasmic Reticulum Stress And Apoptosis In Myocardial Protection By NECA

Objective The aim of this article is to reveal whether ERS (Endoplasmic ReticulumStress) and ERS-induced apoptosis is involved in the cardioprotective effects of adenosinereceptor agonists NECA and explore its possible mechanism.Methods In this study,56Wistar rats of SPF grade were divided into Control group,Ischemia/Reperfusion group, NECA group and TUDCA group. Firstly we examined theeffect of NECA on the cardiac function by using the device of Langendorff isolated ratheart perfusion and RM6240BD multi-channel physiological signal acquisition system tomonitor and record the cardiac function. Secondly, isolated rat hearts were subjected to30min ischemia followed by2h of reperfusion, and myocardial samples were collected fromthe risk zone for Western blot analysis to detect the protein expression of ERS-relatedmolecules GRP94and ERS-induced apoptosis iconic elements CHOP. In addition, TUNELwas used to observe myocardial cell apoptosis. Ultrastructural changes was observed bytransmission electron microscopy. Changes in cardiac pathology was detected by HEstaining.Result1Multi-channel physiological recorder acquisition results showed that: coronaryflow, heart rate and left ventricular developed pressure decreased significantly (P<0.05)during ischemia and reperfusion, but end-diastolic pressure was significantly higher(P<0.05). Granted NECA (100nmol/L) reperfusion can significantly increase coronaryblood flow, heart rate and left ventricular developed pressure (P<0.05), and makes the end-diastolic pressure significantly lower (P<0.05). Tip NECA can improve the cardiacfunction at reperfusion.2Western blot analysis results showed that GRP94expression inI/R group was significantly increased compared to the Sham group (P<0.05) in isolated ratheart at the onset of reperfusion, suggesting that myocardial ischemia/reperfusion injurycan induce ERS. And GRP94expression in NECA group, which NECA was given beforereperfusion, was significantly decreased than the I/R group (P<0.05), it has the sametendency as giving the ERS inhibitor TUDCA (30μmol/L) before reperfusion, indicatingthat NECA can inhibit endoplasmic ERS and protect the heart from ischemia/reperfusioninjury.3Western blot analysis results showed that the expression of CHOP in I/R groupwas significantly increased compared to the Sham group (P<0.05) in isolated rat heart at reperfusion, suggesting that myocardial ischemia/reperfusion injury can induce apoptosis.And CHOP expression in NECA group, which NECA was given before reperfusion, wassignificantly decreased than the I/R group (P<0.05), it has the same tendency as giving theERS inhibitor TUDCA (30μmol/L) before reperfusion, indicating that NECA can inhibitendoplasmic ERS-induced apoptosis and protect the heart from ischemia/reperfusion injury.4Transmission electron microscopy results showed that Sham group mitochondrial neatlyarranged along the long axis of the filaments and endoplasmic reticulum normal when theisolated rat heart reperfused30min, I/R group appeared cardiomyocytes extensivemitochondrial damage, mitochondrial disorder, crest disappeared, edema, or a vacuolardegeneration, dilated endoplasmic reticulum; while after giving NECA, to reduce thedegree of mitochondrial damage, except for some changes in mitochondria, but with nosignificant difference between the control group endoplasmic reticulum morphology werenormal, no significant expansion.5Myocardial apoptosis by TUNEL assay showed thatafter reperfusion for120min, Sham group had no apoptosis occurred, while I/R groupapparent cardiomyocyte apoptosis. Compared with I/R group, group of NECA significantlyreduced apoptotic cells.Conclusions NECA reduces myocardial ischemia/reperfusion injury by inhibitingendoplasmic reticulum stress and apoptosis.