Targeting mitochondrial shape: at the heart of cardioprotection.

There remains an unmet need to identify novel therapeutic strategies capable of protecting the myocardium against the detrimental effects of acute ischemia-reperfusion injury (IRI), to reduce myocardial infarct (MI) size and prevent the onset of heart failure (HF) following acute myocardial infarction (AMI). In this regard, perturbations in mitochondrial morphology with an imbalance in mitochondrial fusion and fission can disrupt mitochondrial metabolism, calcium homeostasis, and reactive oxygen species production, factors which are all known to be critical determinants of cardiomyocyte death following acute myocardial IRI. As such, therapeutic approaches directed at preserving the morphology and functionality of mitochondria may provide an important strategy for cardioprotection. In this article, we provide an overview of the alterations in mitochondrial morphology which occur in response to acute myocardial IRI, and highlight the emerging therapeutic strategies for targeting mitochondrial shape to preserve mitochondrial function which have the future therapeutic potential to improve health outcomes in patients presenting with AMI.

Cardiac phospholipidome is altered during ischemia and reperfusion in an ex vivo rat model.

Acute myocardial infarction (AMI) is the leading cause of death, morbidity, and health costs worldwide. In AMI, a sudden blockage of blood flow causes myocardial ischemia and cell death. Reperfusion after ischemia has paradoxical effects and may exacerbate the myocardial injury, a process known as ischemic reperfusion injury. In this work we evaluated the lipidome of isolated rat hearts, maintained in controlled perfusion (CT), undergoing global ischemia (ISC) or ischemia followed by reperfusion (IR). 153 polar lipid levels were significantly different between conditions. 48 features had q < 0.001 and included 8 phosphatidylcholines and 4 lysophospholipids, which were lower in ISC compared to CT, and even lower in the IR group, suggesting that IR induces more profound changes than ISC. We observed that the levels of 16 alkyl acyl phospholipids were significantly altered during ISC and IR. Overall, these data indicate that myocardial lipid remodelling and possibly damage occurs to a greater extent during reperfusion. The adaptation of cardiac lipidome during ISC and IR described is consistent with the presence of oxidative damage and may reflect the impact of AMI on the lipidome at the cellular level and provide new insights into the role of lipids in the pathophysiology of acute myocardial ischemia/reperfusion injury.

[Effect of electroacupuncture preconditioning on the expressions of NF-κB p65, IκBα and IKKß in myocardial tissue of the rats with acute myocardial ischemia-reperfusion injury].

OBJECTIVE: To observe the effect of electroacupuncture (EA) preconditioning on the expressions of nuclear transcription factors-kappa B (NF-κB) p65, NF-κB inhibitor (IκB) α and IκB kinase (IKK) ß in rats with acute myocardial ischemia-reperfusion injury (MIRI) and to explore the mechanism of EA on heart meridian in relieving MIRI. METHODS: A total of 40 SD rats were randomized into a sham-operation group, a model group, an EA heart meridian group and an EA lung meridian group, 10 rats in each one. In the EA heart meridian group, acupuncture was applied to "Shenmen" (HT 7) and "Tongli" (HT 5). In the EA lung meridian group, acupuncture was applied to "Taiyuan" (LU 9) and "Lieque" (LU 7). In these two groups, EA was exerted for 20 min each time, 1 V in voltage and 2 Hz in frequency once a day. A total of 7-day EA stimulation was required before model duplication. In the model group, the EA heart meridian group and the EA lung meridian group, using ligating left anterior descending coronary artery to establish the acute MIRI models. In the sham-operation group, the chest was open, but no ligation was exerted, just the needle was penetrated through the corresponding sites for one time. The electrocardiogram (ECG) was detected and ST segment displacement was analyzed. Using Western blot method, the relative expressions of NF-κB p65, IκBα and IKKß in myocardial tissue were determined in each group. Using ELISA method, the levels of serum IL-1ß and IL-10 were determined in each group. RESULTS: Compared with the sham-operation group, ST segment displacement value was elevated 30 min after ligating and reperfusion for 120 min in the model group (P<0.05), and the value in the EA heart meridian group was lower than the model group and the EA lung meridian group (P<0.05). Compared with the sham-operation group, the expressions of NF-κB p65 and IKKß in myocardial tissue were increased (P<0.05) and the expression of IκBα reduced in the rats of the model group (P<0.05). Compared with the model group, the expressions of NF-κB p65 and IKKß in myocardial tissue were reduced (P<0.05) and the expressions of IκBα increased in the rats of the EA heart meridian group and the EA lung meridian group (P<0.05). Compared with the EA lung meridian group, the expressions of NF-κB p65 and IKKß in myocardial tissue were reduced (P<0.05) and the expression of IκBα increased in the rats of the EA heart meridian group (P<0.05). Compared with the sham-operation group, the serum level of IL-1ß was increased (P<0.05) and IL-10 reduced in the model group (P<0.05). Compared with the model group, the serum level of IL-1ß was reduced (P<0.05) and IL-10 increased in the EA heart meridian group and the level of IL-1ß was was reduced in the EA lung meridian group (P<0.05). Compared with the EA lung meridian group, the serum level of IL-1ß was reduced (P<0.05) and IL-10 increased in the EA heart meridian group (P<0.05). CONCLUSION: Electroacupuncture preconditioning at heart meridian acupoints obviously alleviates acute MIRI. IKK/IκB/NF-κB signaling pathway possibly participates in the protective mechanism of electroacupuncture preconditioning on acute MIRI.

[Effects of electroacupuncture preconditioning on expression of aquaporin-1 and activity of protein kinase C in myocardium of rats with acute myocardial ischemia-reperfusion injury].

OBJECTIVE: To explore the partial action mechanism and the myocardial protective effect differences between electroacupuncture (EA) preconditioning at "Neiguan"(PC 6) and "Taiyuan"(LU 9) in rats with acute myocardial ischemia-reperfusion injury. METHODS: Ninety-six Wistar rats were randomly assigned into a sham-operation group, a model group, a Neiguan group and a Taiyuan group, 24 rats in each one. The rats in the Neiguan group and Taiyuan group were treated with EA (2 Hz in frequency, 1 mA in intensity) at "Neiguan" (PC 6) and "Taiyuan" (LU 9) respectively, 20 min per treatment, once a day for consecutive 7 days. The rats in the sham-operation group and model group were treated with immobilization for the same time, and no EA was given. The model of myocardial ischemia-reperfusion injury was established in the model group, Neiguan group and Taiyuan group 24 h after the end of EA, while the rats in the sham-operation group were treated with sham operation (no ligation was made during surgery). The myocardial ischemic size, infarction size, activity of protein kinase C (PKC) and expression of aquaporin1 (AQP1) in each group were detected. RESULTS: Compared with sham-operation group, the myocardial ischemic size, infarction size, AQP1 expression and PKC activity in the model group were significantly increased (all P<0.01); compared with the model group and Taiyuan group, the myocardial ischemic size, infarction size, PKC activity and AQP1 expression were significantly decreased in the Neiguan group (P<0.01, P<0.05). By Pearson correlation analysis, the changes of AQP1 expression were positively correlated with those of PKC activity after EA preconditioning. CONCLUSIONS: EA preconditioning at "Neiguan" (PC 6) could significantly decrease myocardial AQP1 expression and PKC activity in rats with acute myocardial ischemia-reperfusion injuing, but the effect of EA preconditioning at "Taiyuan"(LU 9) is not obvious; its protective effect is likely to be achieved by inhibiting PKC activity and AQP1 expression.

Fenofibrate protects against acute myocardial I/R injury in rat by suppressing mitochondrial apoptosis as decreasing cleaved caspase-9 activation.

BACKGROUND AND AIMS: Peroxisome proliferator-activated receptor-α (PPAR-α) activation has been reported to reduce myocardial ischemia-reperfusion (I/R) injury by inhibiting cell apoptosis. However, the antiapoptotic mechanism of PPAR-α is still unknown. Fenofibrate is a PPAR-α agonist In the present study, we investigate the effects and relevant mechanism of fenofibrate on experimental myocardial ischemia-reperfusion (I/R) injury in rats. METHODS: Adult male Wistar rats were pretreated with fenofibrate (80 mg/kg) daily for a period of 7 days. After the treatment period, myocardial I/R injury model was made by left anterior descending coronary artery ligation for 45 min and reperfusion for 120 min. Myocardial infarct size, malondialdehyde (MDA) cleaved-caspase-9 protein expression, PPARα and uncoupling protein 2 (UCP2) mRNA levels in myocardial tissue were detected Cell apoptosis was detected by Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL). Serum lactate dehydrogenase and creatine kinase activities were measured in rats pretreated with fenofibrate The ultrastructure of myocardial tissues was observed. RESULTS: Significant increases in myocardial cell apoptosis, malondialdehyde (MDA) level and cleaved-caspase-9 protein expression level in myocardial tissue were observed, along with reductions of PPARα and uncoupling protein 2 (UCP2) mRNA levels in myocardial tissue of the experimental myocardial ischemia-reperfusion (I/R) injury in rats. Impaired mitochondria were also observed under electron microscopic. However, pretreatment of ischemia/reperfusion rats with fenofibrate brought the biochemical parameters and related genes expression levels to near normalcy, indicating the protective effect of fenofibrate against myocardial ischemia/reperfusion injury in rats. CONCLUSIONS: The PPAR-α activator fenofibrate conferred cytoprotective effect against myocardial ischemia-reperfusion (I/R) injury in rats. Associated mechanisms involved decreased cleaved-caspase-9 expression and decreased cell apoptosis.

Effects of electroacupuncture preconditioning on expression of aquaporin-1 and activity of protein kinase C in myocardium of rats with acute myocardial ischemia-reperfusion injury / 中国针灸

<p><b>OBJECTIVE</b>To explore the partial action mechanism and the myocardial protective effect differences between electroacupuncture (EA) preconditioning at "Neiguan"(PC 6) and "Taiyuan"(LU 9) in rats with acute myocardial ischemia-reperfusion injury.</p><p><b>METHODS</b>Ninety-six Wistar rats were randomly assigned into a sham-operation group, a model group, a Neiguan group and a Taiyuan group, 24 rats in each one. The rats in the Neiguan group and Taiyuan group were treated with EA (2 Hz in frequency, 1 mA in intensity) at "Neiguan" (PC 6) and "Taiyuan" (LU 9) respectively, 20 min per treatment, once a day for consecutive 7 days. The rats in the sham-operation group and model group were treated with immobilization for the same time, and no EA was given. The model of myocardial ischemia-reperfusion injury was established in the model group, Neiguan group and Taiyuan group 24 h after the end of EA, while the rats in the sham-operation group were treated with sham operation (no ligation was made during surgery). The myocardial ischemic size, infarction size, activity of protein kinase C (PKC) and expression of aquaporin1 (AQP1) in each group were detected.</p><p><b>RESULTS</b>Compared with sham-operation group, the myocardial ischemic size, infarction size, AQP1 expression and PKC activity in the model group were significantly increased (all<0.01); compared with the model group and Taiyuan group, the myocardial ischemic size, infarction size, PKC activity and AQP1 expression were significantly decreased in the Neiguan group (<0.01,<0.05). By Pearson correlation analysis, the changes of AQP1 expression were positively correlated with those of PKC activity after EA preconditioning.</p><p><b>CONCLUSIONS</b>EA preconditioning at "Neiguan" (PC 6) could significantly decrease myocardial AQP1 expression and PKC activity in rats with acute myocardial ischemia-reperfusion injuing, but the effect of EA preconditioning at "Taiyuan"(LU 9) is not obvious; its protective effect is likely to be achieved by inhibiting PKC activity and AQP1 expression.</p>

Effect of umbilical cord mesenchymal stem cells on VEGF and MCP-1 of acute myocardial ischemia-reperfusion injury in rats / 国际生物医学工程杂志

Objective To investigate the effects of human umbilical cord mesenchymal stem cells (UC-MSCs ) on vascular endothelial growth factor ( VEGF ) and monocyte chemoattractant protein-1 ( MCP-1 ) of acute myocardial ischemia-reperfusion (AMI-R) injury in rats. Methods 24 Sprague-Dawley rats were randomly divided into sham group, AMI-R group and UCMSCs treatment groups on average. The rats were sacrificed on the 10th day after UCMSCs transplantation, and the myocardial tissues below the ligature were taken. The mRNA and protein expressions of MCP-1 of the tissue were detected by RT-PCR and Western Blot respectively, and the expression of VEGF protein was detected by immunohistochemistry. Results The relative expression levels of MCP-1 mRNA and the protein in UCMSCs group were significantly lower than those in sham group and AMI-R group (all P<0.05). The expression of VEGF protein in UCMSCs group was significantly higher than that in sham group and AMI-R group, the differences were statistically significant(all P<0.05). Conclusion UCMSCs transplantation can promote the angiogenesis and decrease the inflammation reaction in the treatment of acute myocardial ischemia-reperfusion injury.