Attenuation Of Myocardial Ischemia-reperfusion Injury Research Articles

BMSC‑derived exosome‑mediated miR‑25‑3p delivery protects against myocardial ischemia/reperfusion injury by constraining M1‑like macrophage polarization.

Myocardial ischemia/reperfusion injury (MIRI) is a significant challenge in the management of myocardial ischemic disease. Extensive evidence suggests that the macrophage‑mediated inflammatory response may play a vital role in MIRI. Mesenchymal stem cells and, in particular, exosomes derived from these cells, may be key mediators of myocardial injury and repair. However, whether exosomes protect the heart by regulating the polarization of macrophages and the exact mechanisms involved are poorly understood. The present study aimed to determine whether exosomes secreted by bone marrow mesenchymal stem cells (BMSC‑Exo) harboring miR‑25‑3p can alter the phenotype of macrophages by affecting the JAK2/STAT3 signaling pathway, which reduces the inflammatory response and protects against MIRI. An in vivo MIRI model was established in rats by ligating the anterior descending region of the left coronary artery for 30 min followed by reperfusion for 120 min, and BMSC‑Exo carrying miR‑25‑3p (BMSC‑Exo‑25‑3p) were administered through tail vein injection. A hypoxia‑reoxygenation model of H9C2 cells was established, and the cells were cocultured with BMSC‑Exo‑25‑3p in vitro. The results of the present study demonstrated that BMSC‑Exo or BMSC‑Exo‑25‑3p could be taken up by cardiomyocytes in vivo and H9C2 cells in vitro. BMSC‑Exo‑25‑3p demonstrated powerful cardioprotective effects by decreasing the cardiac infarct size, reducing the incidence of malignant arrhythmias and attenuating myocardial enzyme activity, as indicated by lactate dehydrogenase and creatine kinase levels. It induced M1‑like macrophage polarization after myocardial ischemia/reperfusion (I/R), as evidenced by the increase in iNOS expression through immunofluorescence staining and upregulation of proinflammatory cytokines through RT‑qPCR, such as interleukin‑1β (IL‑1β) and interleukin‑6 (IL‑6). As hypothesized, BMSC‑Exo‑25‑3p inhibited M1‑like macrophage polarization and proinflammatory cytokine expression while promoting M2‑like macrophage polarization. Mechanistically, the JAK2/STAT3 signaling pathway was activated after I/R in vivo and in LPS‑stimulated macrophages in vitro, and BMSC‑Exo‑25‑3p pretreatment inhibited this activation. The results of the present study indicate that the attenuation of MIRI by BMSC‑Exo‑25‑3p may be related to JAK2/STAT3 signaling pathway inactivation and subsequent inhibition of M1‑like macrophage polarization.

Role of mitochondrial ATP-sensitive potassium channels in dexmedetomidine-induced attenuation of myocardial ischemia-reperfusion injury in rats

Objective To evaluate the role of mitochondrial ATP-sensitive potassium (mito-KATP) channels in dexmedetomidine-induced attenuation of myocardial ischemia-reperfusion (I/R) injury in rats. Methods Forty pathogen-free healthy male Sprague-Dawley rats, aged 8-12 weeks, weighing 200-350 g, were divided into 5 groups (n=8 each) using a random number table: sham operation group (group S), I/R group, dexmedetomidine group (group DEX), a specific mito-KATP channel blocker 5-hydroxydecanoate (5-HD) group (group 5-HD) and dexmedetomidine plus 5-HD group (group DEX+ 5-HD). Myocardial I/R was produced by occlusion of the anterior descending branch of the left coronary artery for 30 min followed by 120 min reperfusion in pentobarbital sodium-anesthetized rats.Dexmedetomidine 5 μg/kg was intraperitoneally injected at 15 min prior to reperfusion in group DEX.5-HD 40 mg/kg was intraperitoneally injected at 30 min prior to reperfusion in group 5-HD.In group DEX+ 5-HD, 5-HD 40 mg/kg and dexmedetomidine 5 μg/kg were intraperitoneally injected at 30 and 15 min prior to reperfusion, respectively.The parameters of cardiac function such as left ventricular systolic pressure (LVSP), left ventricular end-diastolic pressure (LVEDP) and the maximum rate of increase or decrease in left ventricular pressure (±dp/dtmax) were recorded before ischemia (T0) and at 60 and 120 min of reperfusion (T1, 2). Blood samples were collected from the carotid artery at the end of reperfusion for determination of the concentrations of creatine kinase-MB (CK-MB) and cardiac troponin I (cTnI) in serum.The animals were then sacrificed, and hearts were removed for determination of the myocardial infarct size in the left ventricular myocardial tissues. Results Compared with group S, the LVSP and ±dp/dtmax were significantly decreased, and the LVEDP was increased at T1-2, and the concentrations of CK-MB and cTnI in serum and myocardial infarct size were increased in the other groups (P 0.05). Compared with group DEX, the LVSP and ±dp/dtmax were significantly decreased, and the LVEDP was increased at T1-2, and the concentrations of CK-MB and cTnI in serum and myocardial infarct size were increased in DEX+ 5-HD group (P<0.05). Conclusion The mechanism by which dexmedetomidine attenuates myocardial I/R injury is partially related to promotion of mito-KATP channel opening in rats. Key words: KATP channels; Dexmedetomidine; Myocardial reperfusion injury

Role of ATP-sensitive K+ channels in oxycodone postconditioning-induced attenuation of myocardial ischemia-reperfusion injury in rats

Objective To evaluate the role of ATP-sensitive K+ channels (KATP channels) in oxycodone postconditioning-induced attenuation of myocardial ischemia-reperfusion (I/R) injury in rats. Methods Forty healthy adult male Sprague-Dawley rats, aged 8-12 weeks, weighing 200-300 g, were randomly divided into 4 groups (n=10 each) using a random number table: sham operation group (group S), group I/R, oxycodone postconditioning group (group OP), and KATP channel blocker glibenclamide plus oxycodone postconditioning group (group GOP). Myocardial I/R was produced by 30 min occlusion of the anterior descending branch of the left coronary artery followed by 120 min reperfusion.In group S, the anterior descending branch of the left coronary artery was only exposed but not ligated.In group GOP, glibenclamide 1 mg/kg was injected via the jugular vein before ischemia.In OP and GOP groups, oxycodone 0.5 mg/kg was injected via the jugular vein at 5 min prior to reperfusion, and the equal volume of normal saline was given in S and I/R groups.At 120 min of reperfusion, blood samples were collected from the carotid artery for determination of the level of serum cardiac troponin I (cTnI). The animals were then sacrificed, and the hearts were removed for determination of the myocardial infarct size in the left ventricle. Results Compared with group S, the concentration of serum cTnI and myocardial infarct size were significantly increased in I/R, OP and GOP groups (P<0.05). Compared with group I/R, the concentration of serum cTnI and myocardial infarct size were significantly decreased in OP and GOP groups (P<0.05). Compared with group OP, the concentration of serum cTnI and myocardial infarct size were significantly increased in group GOP (P<0.05). Conclusion KATP channel opening is involved in oxycodone postconditioning-induced attenuation of myocardial I/R injury in rats. Key words: KATP channels; Oxycodone; Ischemic postconditioning; Myocardial reperfusion injury

Sparstolonin B attenuates hypoxia-induced apoptosis, necrosis and inflammation in cultured rat left ventricular tissue slices.

Ischemia/reperfusion results in tissue damage, a rapid increase in cytokines and chemokines and inflammatory cell infiltration. Herein we investigated the ability of a selective TLR2/4 antagonist, Sparstolonin B (SsnB), to protect rat cultured left ventricular tissue (LV) slices from hypoxic injury by inhibiting the myocardial inflammatory response independent of inflammatory cell infiltration. Media Lactate dehydrogenase (LDH) levels were measured to reflect hypoxia-induced cytotoxicity and cell injury with and without SsnB. Incubation with SsnB (15 and 30 μM) significantly reduced by 20 and 40%, respectively, the amount of LDH released from the hypoxic LV slices. TUNEL staining showed that SsnB significantly attenuated the levels of hypoxia-induced apoptotic cells from 61.5 ± 4.0 to 27.0 ± 2.1 (15 μM SsnB) and 23.5 ± 2.2 (30 μM SsnB) cells/unit area. Similarly, the Periodic Acid-Schiff (PAS) staining of ischemic areas in untreated hypoxic LV slices was increased 17 fold from 0.26± 0.09 to 4.41 ± 0.43%, while in hypoxic slices incubated with 15 and 30 μM of SsnB, the PAS positive ischemic areas were increased by only 6.4 fold to 1.66 ± 0.39% and 3.8 fold to 1.00 ± 0.22%, respectively. Rt-PCR confirmed that MCP1 and IL-6 expression during hypoxia was elevated by 2 and 4 fold, respectively, while their up-regulation was significantly inhibited (i.e., < 0.7 fold increase) by SsnB. The selective TLR2/4 antagonist, Sparstolonin B, can substantially protect LV myocardium via its ability to inhibit injury resulting from hypoxic myocardial-generated inflammation. Accordingly SsnB has potential as a therapeutic agent for the attenuation of myocardial ischemia-reperfusion injury.

Role of delta and kappa opioid receptors in sufentanil preconditioning-induced attenuation of myocardial ischemia-reperfusion injury in rats

Objective To evaluate the role of delta and kappa opioid receptors in sufentanil preconditioning (SPC)-induced attenuation of myocardial ischemia-reperfusion (I/R) injury in rats.Methods Forty adult male Sprague-Dawley rats,aged 2-3 months,weighing 250-330 g,were randomly divided into 5 groups (n =8 each) using a random number table:sham operation group (group S),group I/R,group SPC,δ receptor antagonist naltrindole + SPC group (NTD + SPC group),and κ receptor antagonist nor-binaltorphimine (nor-BNI) + SPC group (BNI + SPC group).Myocardial I/R was induced by 30 min occlusion of left anterior descending branch of coronary artery followed by 120 min reperfusion.In group SPC,5 min infusion of sufentanil 3μg/kg was repeated 3 times at 5 min interval before myocardial ischemia.In NTD + SPC group,naltrindole 5 mg/kg was intravenously injected,at 10 before SPC.In BNI + SPC group,nor-BNI 5 mg/kg was injected intravenously at 15 min before SPC.Arterial blood samples were collected at 120 min of reperfusion for measurement of the serum cardiac troponin I (cTnI) and creatine kinase isoenzyme-MB (CK-MB) concentrations.The rats were then sacrificed and hearts removed for determination of myocardial infarct size (IS) and area at risk (AAR).IS/AAR ratio was calculated.Results Compared with S group,the serum cTnI and CK-MB concentrations were significantly increased in I/R,NTD + SPC and BNI + SPC groups,and the serum CK-MB concentrations were increased in SPC group,and IS/AAR ratio was increased in I/R group (P ＜ 0.05 or 0.01).The serum cTnI and CK-MB concentrations were significantly lower in SPC,NTD + SPC and BNI + SPC groups and IS/AAR ratio was lower in SPC and BNI + SPC groups than in I/R group,and higher in NTD + SPC and BNI + SPC groups than in SPC group (P ＜ 0.05 or 0.01).Conclusion Both κ and δ opioid receptors mediate SPC-induced attenuation of myocardial I/R injury in rats. Key words: Receptors, opioid ; Sufentanil ; Ischemic preconditioning; Myocardial reperfusion injury

Role of different opioid receptors in sufentanil postconditioning-induced attenuation of myocardial ischemia-reperfusion injury in rats

Objective To evaluate the role of different opioid receptors in sufentanil postconditioning-induced attenuation of myocardial ischemia-reperfusion (I/R) injury in rats.Methods Fifty adult male Sprague-Dawley rats,aged 4-6 months,weighing 200-330 g,were randomly divided into 9 groups:I/R group (n =7),ischemic postconditioning (IPC) group (n =7),sufentanil postconditiong (SP) group (n =6),κ-opioid receptor antagonist nor-binaltorphimine (nor-BNI) + SP group (group BNI + SP,n =5),δ-opioid receptor antagonist naltrindole + SP group (group NTD + SP,n =5) and μ-opioid receptor antagonist CTOP + SP group (group CTOP +SP,n =5).Myocardial I/R was produced by 30 min occlusion of left anterior descending branch of coronary artery followed by 120 min reperfusion.IPC was induced by 3 episodes of 10 s reperfusion followed by 10 s ischemia at the end of 30 min myocardial ischemia.Sufentanil 1 μg/kg was injected intravenously at 5 min before reperfusion in SP group.In groups BNI + SP,NTD + SP and CTOP + SP,nor-BNI 5 mg/kg,naltrindole 5 mg/kg and CTOP 1 mg/kg were injected intravenously,respectively,before SP and the corresponding doses of nor-BNI,naltrindole and CTOP were injected intravenously,respectively,at 5 min before reperfusion.Arterial blood samples were collected at 120 min of reperfusion for measurement of the plasma cardiac tropnin I (cTnI) concentration.The rats were then sacrificed and hearts removed for determination of myocardial infarct size (IS) and area at risk (AAR).IS/AAR was calculated.Results Compared with I/R group,the plasma cTnI concentration and IS/AAR were significantly decreased in groups IPC,SP,BNI + SP and NTD + SP (P ＜ 0.05),and no significant change was found in the plasma cTnI concentration and IS/AAR in groups CTOP + SP,NTD,BNI and CTOP (P ＞ 0.05).Compared with SP group,IS/AAR was increased in NTD + SP and BNI + SP groups and the plasma cTnI concentration and IS/AAR were significantly increased in CTOP + SP group (P ＜ 0.05).Conclusion The μ-,κ-and δ-opioid receptors mediate sufentanil postconditioning-induced attenuation of myocardial I/R injury in rats. Key words: Sufentanil ; Receptors, opioid ; Myocardial reperfusion injury

Effect of diabetes mellitus factor on attenuation of myocardial ischemia-reperfusion injury by sufentanil postconditioning in rats

Objective To investigate effect of diabetes mellitus factor on attenuation of myocardial ischemia-reperfusion injury by sufentanil postconditioning in rats.Methods Diabetes mellitus was established by intraperitoneal streptozotocin 50 mg/kg and was confirmed by blood glucose ≥ 16.7 mmol/L.Thirty healthy adult male SD rats,weighing 250-300 g which diabetes mellitus model was successfully established were randomly divided into 3 groups ( n =10 each):diabetic mellitus sham operation group (group DM-S),diabetic mellitus ischemia-reperfusion group (group DM-IR) and diabetic meltitus sufentanil postconditioning group (group DM-SP).Another 30nondiabetic mellitus rats were also randomly divided into 3 group ( n =10 each):nondiabetic mellitus sham operation group (group NDM-S),nondiabetic mellitus ischemia-reperfusion group (group NDM-IR) and nondiabetic mellitus sufentanil postconditioning group (group NDM-SP).Myocardial ischemia-reperfusion was induced by 30 min occlusion of left anterior descending branch of coronary artery followed by reperfusion.Sufentanil postconditioning was induced by iv injection of sufentanil 1.0 μg/kg at 5 min before reperfusion.MAP,SBP,HR and RPP (HR × SBP) were recorded before ischemia,30 min of ischemia and 120 min of reperfusion.Arterial blood samples were collected at 120 min of reperfusion for measurement of plasma cardiac troponin 1 (cTnI) concentration.The animals were then sacrificed for determination of total areas of right and left ventricles ( LV + RV),infarct area (IS),area at risk (AAR) and IS/AAR.Results MAP and RPP were significantly lower,while plasma cTnI concentration was higher during myocardial ischemia reperfusion in diabetic and nondiabetic rats.Sufentanil postconditioning significantly decreased IS,IS/AAR and plasma cTnI concentration in nondiabetic rats during myocardial ischemia reperfusion but had no effect on IS,IS/AAR and plasma cTnI concentration in diabetic rats.The IS,IS/AAR and plasma cTnI concentration were significantly higher in DM-SP group than in NDM-SP gnoup ( P ＜ 0.05).Conclusion Diabetes mellitus factor can negate sufentanil postconditioning induced protection against myocardial ischemia-reperfusion injury in rats. Key words: Diabetes mellitus; Sufentanil; Myocardial reperfusion injury; Postconditioning

Role of Janus kinase 2/signal transducer and activator of transcription 3 signaling pathway in attenuation of myocardial ischemia-reperfusion injury by teramethylpyrazine in rats

Objective To evaluate the role of Janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) signaling pathway in attenuation of myocardial ischemia-reperfusion (I/R) injury by tetramethylpyrazine in rats.Methods Sixty-four healthy male Wistar rats weighing 250-300 g were randomly divided into 4 groups( n ＝ 16 each):sham operation group (group S),myocardial I/R group(group I/R),teramethylpyrazine group (group T) and AG,490( a JAK2 inhibitor) group (group AG).Myocardial I/R was induced by 30 min occlusion of left anterior desecending coronary artery (LAD) followed by 120 min reperfusion in groups I/R,T and A.In groups T and A teramethylpyrazine 20 mg/kg was injected iv 20 min before LAD occlusion.In group A AG490 3 tμg/g was injected iv at 5 min before reperfusion.Blood samples were then taken from inferior vena cava at 120 min of reperfusion for measurement of serum creatine phosphokinase (CK) and lactose dehydrogenase (LDH) activities.Myocardial infarct size was then measured and myocardial tissue was obtained for microscopic examination.Results Serum CK and LDH activities were significantly higher in group I/R than in group S.Pretreatment with tetramethylpyrazine significantly decreased myocardial infarct size and I/R-induced increase in serum CK and LDH activities and histologic damage.The protective effect of tetramethylpyrazine against myocardial 1/R injury was attenuated by postconditioning with AG490.Conclusion JAK2/STAT3 signaling pathway is involved in attenuation of myocardial I/R injury by tetramethyl pyrazine in rats. Key words: TETRAMETHYLPYRAZINE; Myocardial reperfusion injury; Janus kinase 2; STAT3transcription factor

Role of autophagy in attenuation of myocardial ischemia-reperfusion injury by diazoxide in isolated rat heart

Objective To evaluate the role of autophagy in attenuation of myocardial ischemia-reperfusion (I/R) injury by diazoxide in the isolated rat heart.Methods Thirty-two male SD rats were randomly assigned into 4 groups ( n = 8 each) : I/R group, diazoxide group (group D), an inhibitor of autophagy wortmannin + diazoxide group (group WT＞) and wortmannin group (group W) . The animals were anesthetized with intraperitoneal pento-barbital sodium 40 mg/kg. Their hearts were excised and passively perfused in a Langendorff apparatus with an oxygenated (95% O2-5% CO2 ) K-H solution at 37 °C . The isolated hearts were made globally ischemic for 20 min followed by 30 min reperfusion. In I/R and W groups, the isolated hearts were perfused with K-H solution for 10 min before ischemia, while the isolated hearts were perfused with K-H solution containing diazoxide 100 /xmol/L for 10 min before ischemia in D and WD groups. The HR, left ventricular end-diastolic pressure (LVEDP) and left ventricular developed pressure (LVDP) were recorded immediately before perfusion with diazoxide, immediately before the end of perfusion and at 30 min of reperfusion.Myocardial tissues were obtained at 30 min of reperfusion for determination of SOD activity, MDA content and autophagy-related protein Beclin-1 expression (by immunohistochemistry). The formation of autophagosomes was observed by transmission electron microscopy. ResultsCompared with group I/R, LVDP, HR, SOD activity and Beclin-1 expression were significantly increased at 30 min of reperfusion, while LVEDP and MDA content were significantly decreased at 30 min of reperfusion in group D(P＜0.05),and Beclin-1 expression was significantly decreased in WD and W groups(P＜0.05).Compared with group D, LVDP and Beclin-1 expression were significantly decreased, and MDA content was significantly increased in WD and W groups, and LVEDP was significantly increased, while SOD activity decreased in group W (P＜0.05). Microscopic examination showed that a large number of autophagosomes, a small number of autophagosomes and an extremely small number of autophagosomes were observed in D, WD and I/R groups respectively. Conclusion Autophagy is involved in attenuation of myocardial I/R injury by diazoxide in the isolated rat heart. Key words: Autophagy; Diazoxide; Myocardial reperfusion injury

Role of mitochondrial permeability transition pore in attenuation of myocardial ischemia-reperfusion injury by delayed preconditioning with sevoflurane in rats

Objective To investigate the role of mitochondrial permeability transition pore (mPTP) in attenuation of myocardial ischemia-reperfusion (I/R) injury by delayed preconditioning with sevoflurane in rats.Methods Eighty male SD rats, weighing 250-300 g, were randomly assigned into 5 groups ( n = 16 each): Ⅰsham operation group (group S), Ⅱ group I/R, Ⅲ sevoflurane delayed preconditioning group (group SP), Ⅳ the mPTP opener atractyloside + sevoflurane delayed preconditioning group (group A + SP), and Ⅴ atractyloside group (group A). Myocardial I/R was induced by ligation of anterior descending branch of left coronary artery for 30 min followed by 120 min of reperfusion in group I/R, SP, A + SP and A. In group SP and A + SP, 2.5%sevoflurane was inhaled for 1 h, while pure oxygen was inhaled for 1 h in the other groups, and then myocardial ischemia was performed 24 h later. In group A + SP and A, atractyloside 5 mg/kg was injected intravenously via caudal vein 15 min before ischemia. Blood samples were taken from carotid arteries for detection of serum cardiac troponin-Ⅰ (cTnI) concentrations at the end of reperfusion. Then the rats were sacrificed and hearts removed. The myocardial infarct size (IS) and expression of Bcl-2 and Bax in the myocardium were determined. Myocardial ultrastructure was examined with the electron microscope. Results Serum cTnI concentrations and Bax expression were significantly higher, the myocardial IS was significantly larger and Bcl-2 expression was significantly lower in the other groups than in group S ( P ＜ 0.05). Serum cTnI concentrations and Bax expression were significantly lower, the myocardial IS was significantly smaller and Bcl-2 expression was significantly higher in group SP than in group I/R ( P ＜ 0.05). Microscopic examination showed less damage in group SP than in group I/R. The protection provided by sevoflurane preconditioning was abolished by atractyloside. Conclusion Inhibition of mPTP opening can result in an up-regulation of Bcl-2 expression and down-regulation of Bax expression, which plays a role in attenuation of myocardial I/R injury by delayed preconditioning with sevoflurane in rats. Key words: Mitochondrial membrane transport proteins; Mitochondria, heart; Ischemic preconditioning, myocardial; Myocardial reperfusion injury; Sevoflurane

Nicorandil-induced Neural Protection might Contribute to the Attenuation of Myocardial Ischemia-Reperfusion Injury

Nicorandil-induced Neural Protection might Contribute to the Attenuation of Myocardial Ischemia-Reperfusion Injury

Anti‐inflammatory effect of high‐dose insulin treatment after urgent coronary revascularization surgery

The administration of insulin has been shown to exert cardioprotective and immunomodulatory properties. Ischemia and inflammation are typical features of acute coronary syndrome, thus it was hypothesized that high-dose glucose-insulin-potassium (GIK) treatment could suppress the systemic inflammatory reaction and attenuate myocardial ischemia-reperfusion injury in patients with unstable angina pectoris after urgent coronary artery bypass surgery. Forty patients with unstable angina pectoris scheduled for urgent coronary artery bypass surgery and cardiopulmonary bypass were randomly assigned to receive either high-dose insulin treatment (short-acting insulin 1 IU/kg/h with 30% glucose 1.5 ml/kg/h administered separately) or control treatment (saline). Blood glucose levels were targeted to 6.0-8.0 mmol/l in both groups by adjusting the rate of glucose infusion in the GIK group and by additional insulin in the control group as needed. High-dose insulin treatment was associated with significantly lower average C-reactive protein (23.8 vs. 40.1 mg/l, P= 0.008) and free fatty acid levels (0.22 vs. 0.41 mmol/l, P= < 0.001) post-operatively. Average blood glucose levels were comparable during the intensive care unit (ICU) stay (7.1 vs. 6.9 mmol/l, P= 0.5) and 95% of the control patients received supplemental insulin. The pro-inflammatory cytokine response [interleukin-6 (IL-6), interleukin-8 (IL-8) and tumor necrosis factor-alpha (TNF-alpha)] did not differ between the groups and beneficial effects on myocardial injury were not detected. High-dose insulin treatment has potential anti-inflammatory properties independent of its ability to lower blood glucose levels. Even profound suppression of free fatty acid levels, the attenuation of myocardial ischemia-reperfusion injury was not detected.

Comparison of two gene transfer models for the attenuation of myocardial ischemia–reperfusion injury following preservation for cardiac transplantation☆

Two models of ex vivo gene transfer were compared by examining the protective effect of adenovirus-mediated transfection of a free radical scavenger superoxide dismutase (SOD) during experimental ischemia-reperfusion mimicking preservation for cardiac transplantation. Donor rat hearts (n=6 per group) were infused (subgroups IA and IB) or continually perfused (subgroups IIA and IIB) with solution containing adenoviral vector carrying beta-galactosidase (subgroups IA and IIA) or Mn-SOD (subgroups IB and IIB) over 5s with 1h storage and 15 min, at 4 degrees C, respectively. Hearts were then implanted heterotopically into the abdomen of recipient rats. Four days later, transplanted hearts were collected, connected to Langendorff perfusion apparatus and subjected to 6h of ischemia followed by 1h of reperfusion. Cardiac function was evaluated using intraventricular balloon at the beginning of Langendorff perfusion and following ischemia-reperfusion. Blue staining from hydrolyses of X-gal by beta-galactosidase was confirmed in AdLacZ transduced hearts. Immunoreactivity with anti-human Mn-SOD antibody then staining was positive in AdMnSOD-transduced hearts. Percent recovery of preischemic left ventricular developed pressure (LVDP) increased from 55.9+/-3.1% to 67.3+/-6.2% (P=0.048) and from 58.0+/-8.0% to 78.9+/-6.0% (P<0.001) in subgroups IA, IB, IIA and IIB, respectively. The difference in LVDP recovery between treatment groups of the two transfection methods (IB vs IIB) was significant (P=0.044). Adenoviral Mn-SOD ex vivo delivery using continuous myocardial perfusion is superior to bolus infusion in the attenuation of myocardial ischemia-reperfusion injury.

Attenuation of Myocardial Ischemia-Reperfusion Injury by Trimetazidine Derivatives Functionalized with Antioxidant Properties

Trimetazidine (TMZ), an anti-ischemic metabolic drug, is used to treat chest pain (angina pectoris). We hypothesized that derivatives of TMZ with antioxidant functions may improve the cardiac dysfunction caused by ischemia-reperfusion (I/R) above that observed with TMZ alone. Isolated rat hearts perfused with Krebs-Henseleit buffer according to the Langendorff method were subjected to 30 min of global ischemia followed by 45 min of reperfusion. Trimetazidine, TMZ-NH (TMZ modified with a pyrroline moiety), or TMZ-PhiNH (TMZ-NH with a phenyl substitute) were infused (50 microM) for 1 min before the onset of ischemia. Untreated (control) hearts at the end of 45 min of reperfusion showed a significant decrease in the recovery of coronary flow (42%), left ventricular-developed pressure (22%), and rate-pressure product (25%) compared with preischemic baseline values. The I/R hearts also showed markedly increased lactate dehydrogenase and creatine kinase activities in the coronary effluent, significant myocardial infarction (46% of risk area), and activation of Akt, extracellular signal-regulated kinase, and p38 mitogen-activated protein kinase. Pretreatment of hearts with TMZ-NH or TMZ-PhiNH significantly enhanced the recovery of heart function and decreased infarct size. The I/R-induced activation of Akt was further enhanced by TMZ-PhiNH. The present study demonstrated that TMZ-NH and TMZ-PhiNH significantly protected hearts against I/R-mediated cardiac dysfunction and injury. The protective effect of the TMZ derivatives could be due to the combined effects of antioxidant and anti-ischemic activities as well as enhanced pro-survival Akt activity.

Attenuation of myocardial ischemia-reperfusion injury with nitric oxide replacement therapy

The coronary vascular endothelium produces nitric oxide (NO) during the conversion of L-arginine to L-citrulline. Although NO is a potent vasodilator, at lower concentrations, it also has antineutrophil actions that reduce the inflammatorylike components of ischemia-reperfusion injury. The endothelium is damaged in the early minutes after reperfusion, ie, before neutrophils accumulate and before myocardial necrosis fully develops, and this suggests that endothelial injury is a springboard event in the postischemic inflammatory cascade. Studies of coronary artery occlusion and reperfusion suggest that early damage to the coronary endothelium impairs NO production, which, in turn, abrogates the endogenous antineutrophil effects of NO. However, this impaired endogenous NO-related cardioprotection can be restored either by providing specifically at the onset of reperfusion the precursor to NO (L-arginine) or by providing agents that donate NO. In studies, L-arginine or NO donors reduce infarct size in models of coronary occlusion and reperfusion. The mechanism or mechanisms of this cardioprotection involve preservation of endothelial function and inhibition of neutrophil accumulation in ischemic-reperfused tissue. The cardioprotective potential of NO offers a new therapeutic approach to the reduction of ischemia-reperfusion injury after coronary artery occlusion.