Activated Protein C Protects Myocardium Via Activation of Anti-apoptotic Pathways of Survival in Ischemia-reperfused Rat Heart

Activated protein C (APC) is known to be beneficial on ischemia reperfusion injury in myocardium. However, the protection mechanism of APC is not fully understood. The purpose of this study was to investigate the effects and possible mechanisms of APC on myocardial ischemic damage. Artificially ventilated anaesthetized Sprague-Dawley rats were subjected to a 30 min of left anterior descending coronary artery occlusion followed by 2 hr of reperfusion. Rats were randomly divided into four groups; Sham, I/R, APC preconditioning and postconditioning group. Myocardial infarct size, apoptosis index, the phosphorylation of ERK1/2, Bcl-2, Bax and cytochrome c genes and proteins were assessed. In APC-administrated rat hearts, regardless of the timing of administration, infarct size was consistently reduced compared to ischemia/reperfusion (I/R) rats. APC improved the expression of ERK1/2 and anti-apoptotic protein Bcl-2 which were significantly reduced in the I/R rats. APC reduced the expression of pro-apoptotic genes, Bax and cytochrome c. These findings suggest that APC produces cardioprotective effect by preserving the expression of proteins and genes involved in anti-apoptotic pathways, regardless of the timing of administration.

The effect of protease-activated receptor2 on rat apoptotic cardiomyocytes underwent ischemia reperfusion injury / 中华心血管病杂志

<p><b>OBJECTIVE</b>To investigate the effect of protease-activated receptor 2 (PAR-2) on rat apoptotic cardiomyocytes underwent ischemia reperfusion (I/R) injury.</p><p><b>METHODS</b>Healthy male Sprague-Dawley rats were randomly divided into five groups (n = 8 each): sham-operation group, I/R (ligating the left coronary artery for 30 minutes and followed by 120 minutes reperfusion) group and three SLIGRL-NH2 groups treated with intravenous PAR-2 agonist SLIGRL-NH2 at different doses (0.5, 1, 3 mg/kg) 5 minutes before reperfusion. Apoptic cardiomyocytes was detected by TUNEL staining and by DNA ladder on agarose gel electrophoresis. Bax and Bcl-2 expression in myocardium was analyzed by immunohistochemical technique. The mRNA expression of PAR-2 was determined by Real-time quantitative polymerase chain reaction (RT-PCR).</p><p><b>RESULTS</b>(1) The apoptosis index and the expression of Bcl-2 and Bax were significantly increased in IR group and SLIGRL-NH2 groups than those in sham group (P < 0.05-0.01). (2) Compared with I/R group, the apoptosis index and the expression of Bax were significantly reduced while the expression of Bcl-2 and PAR-2 mRNA were significantly upregulated by SLIGRL-NH2 in a dose-dependent manner. (3) DNA Agarose gel electrophoresis demonstrated that DNA ladder existed in I/R and 0.5 mg/kg SLIGRL-NH2 group, but not in 1, 3 mg/kg SLIGRL-NH2 groups.</p><p><b>CONCLUSIONS</b>PAR-2 agonist SLIGRL-NH2 could reduce myocardial apoptosis by upregulating the Bcl-2 and PAR-2 mRNA level and downregulating Bax expression in a dose-dependent manner in this rat I/R model.</p>

Myocardial toll like receptor 4 expression in a rat model of myocardial ischemia reperfusion injury / 中华心血管病杂志

<p><b>OBJECTIVE</b>To explore the role of TLR4 in myocardial ischemia reperfusion injury (MI/RI) by observing the dynamic TLR4 expression changes at mRNA and protein levels early after myocardial ischemia reperfusion.</p><p><b>METHODS</b>Male SD rats were randomly divided into Sham and IR group and the rats were killed according to different reperfusion time (0, 0.5, 1, 2, 4 and 8 hours). Myocardial changes under light microscope and transmission electronic microscope were observed. TLR4 expressions at protein and mRNA levels were detected by immunohistochemistry and realtime RT-PCR respectively. Myocardial TNF-alpha was determined by ELISA.</p><p><b>RESULTS</b>(1) Myocardial injury was observed in IR but not in Sham group and histopathological and ultrastructural changes in IR group remained unchanged up to 8 hours after reperfusion. (2) Positive TLR4 protein staining was visualized in both Sham and IR groups and significantly increased and peaked at 1 hour of reperfusion in IR group. (3) Compared to Sham group, TLR4 mRNA level was upregulated in myocardium in IR group and peaked at 1 hour of reperfusion. (4) Concentration of TNF-alpha in IR group was significantly higher than that of Sham group at corresponding time points (all P < 0.05), and myocardial TLR4 mRNA level correlated positively with myocardial TNF-alpha (r = 0.728, P < 0.01).</p><p><b>CONCLUSION</b>Expression of TLR4 in myocardium during early after myocardial ischemia reperfusion was upregulated and actived TLR4 might play an important role in MI/RI through promoting myocardial TNF-alpha excretion.</p>

Application status of using clopidogrel during perioperative period of percutaneous coronary intervention / 中国临床药理学与治疗学

Percutaneous coronary intervention(PCI) has become one of the most important therapeutic methods for atherosclerotic heart disease(AHD),but the following complications such as stent thrombosis and restenosis af- fected its long-term efficacy.Platelet activation was a key component of thrombosis of during perioperative period PCI.As one of the most effective antiplatelet drugs,clo- pidogrel has been established its important role in preven- ting thrombosis during perioperative period of PCI.After several large-scale clinical trials in recent years.

Adenosine protects cardiomyocytes from hypoxia/reoxygenation injury / 生理学报

The aim of this study was to investigate the protective effect of adenosine (ADO) on cardiomyocytes following hypoxia/reoxygenation (H/R) and its molecular mechanism. Primary cultured cardiomyocytes of neonatal rats were divided into two groups, namely H/R (control) and ADO (1.0 micromol/L) groups. The morphologic changes in cardiomyocytes were observed under an inverted phase-contrast microscope. The following parameters of the two groups were determined: lactate dehydrogenase (LDH) activity, intracellular calcium concentration and malondialdehyde (MDA) content. Tumor necrotic factor (TNF-alpha) assay was performed using an ELISA kit and NF-kappaB in the nucleus was analyzed by electrophoretic mobility shift assay (EMSA). The results are as follows: (1) after H/R injury, cardiomyocytes contracted, tending to get round in shape and its pseudopods decreased, while marked morphological changes were not observed in ADO group; (2) LDH leakage maintained at a lower level in ADO group than that in the control group during H/R (both P<0.01); (3) ADO significantly reduced the concentration of calcium in cells and prevented calcium overload during H/R (both P<0.01); (4) ADO markedly reduced the content of MDA during H/R (both P<0.01); (5) ADO inhibited the production of TNF-alpha during H/R (both P<0.01); and (6) ADO down-regulated NF-kappaB binding activity of cardiomyocytes during H/R (both P<0.01) The results suggest that (1) exogenous ADO attenuates H/R injury of cultured cardiomyocytes; (2) exogenous ADO inhibits the production of TNF-alpha after H/R injury; (3) exogenous ADO prevents the activation of NF-kappaB, which may be the molecular mechanism of down-regulation of TNF-alpha expression.