Reduction Of Myocardial Ischemia-reperfusion Injury Research Articles

Role of TRPV1/CGRP signaling pathway in lidocaine postconditioning-induced reduction of myocardial ischemia-reperfusion injury in rats

Objective To evaluate the role of transient receptor potential vanillic acid subtype 1(TRPV1)/calcitonin gene-related peptide(CGRP) signaling pathway in lidocaine postconditioning-induced reduction of myocardial ischemia-reperfusion(I/R) injury in rats. Methods Forty healthy male Sprague-Dawley rats, aged 3 months, weighing 250-300 g, were divided into 5 groups(n=8 each) using a random number table method: sham operation group(group Sham), group I/R, lidocaine postconditioning group(group LP), lidocaine postconditioning plus CGRP8-37 group(group LP+ CGRP8-37), and lidocaine postconditioning plus capsazepine group(group LP+ Capz). Myocardial ischemia was induced by ligating the anterior descending branch of left coronary artery for 30 min, followed by 120-min reperfusion in anesthetized rats. Lidocaine 2 mg/kg was injected via the tail vein at 5 min before reperfusion in group LP. In group LP + CGRP8-37, lidocaine was intravenously injected, and CGRP receptor selective antagonist CGRP8-37 2 mg/kg was intravenously injected at the same time. In group LP+ Capz, lidocaine was injected intravenously, and TRPV1 blocker capsazepine 3 mg/kg was injected intravenously at the same time. A catheter was retrogradely implanted to the left ventricle, and heart rate(HR), 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 continuously monitored and recorded. Blood samples were collected from the carotid artery at 120 min of reperfusion for determination of cardiac troponin I(cTnI), myoglobin(Myo) and creatine kinase-MB(CK-MB) concentrations in serum. Rats were then sacrificed for determination of myocardial infarct size. Results Compared with Sham group, the serum concentrations of cTnI, Myo and CK-MB were significantly increased, LVSP, + dP/dtmax and HR were decreased, and LVEDP and -dP/dtmax were increased in I/R group and LP group(P 0.05). Compared with group LP, the serum concentrations of cTnI and Myo, myocardial infarct size and LVEDP were significantly increased, and + dP/dtmax was decreased in group LP+ CGRP8-37, and the serum concentrations of cTnI and Myo and myocardial infarct size were significantly increased, LVSP and + dP/dtmax were decreased, and LVEDP was increased in group I/R+ Lido+ Capz(P<0.05). Conclusion The mechanism by which lidocaine postconditioning mitigates myocardial I/R injury is related to activating TRPV1/CGRP signaling pathway in rats. Key words: Lidocaine; Ischemia postconditioning; Myocardial reperfusion injury; Calcitonin gene-related peptide; TRPV cation channels

Role of mito-KATP channel in pinacidil postconditioning-induced reduction of myocardial ischemia-reperfusion injury in rats: an in vitro experiment

Objective To evaluate the role of mitochondrial KATP (mito-KATP) channel in pinacidil postconditioning-induced reduction of myocardial ischemia-reperfusion (I/R) injury in rats. Methods SPF healthy male Sprague-Dawley rats, aged 16-20 weeks, weighing 250-300 g, were anesthetized with pentobarbital.Their hearts were excised and perfused in a Langendorff apparatus with K-H solution saturated with 95% O2-5% CO2 at 36.5-37.5 ℃.Thirty-two Langendorff-perfused hearts were divided into 4 groups (n=8 each) using a random number table: control group (group C), group I/R, pinacidil postconditioning group (group P) and 5-hydroxy decanoic acid plus pinacidil postconditioning group (group 5-HD+ P). Myocardial ischemia was induced by interrupting perfusion for 40 min followed by 60 min reperfusion.Immediately after onset of reperfusion, hearts were perfused with K-H solution containing 50 μmol/L pinacidil for 2 min and then with K-H solution for 58 min in group P, hearts were perfused with K-H solution containing 100 μmol/L 5-HD for 5 min, with K-H solution containing 50 μmol/L pinacidil for 2 min and then with K-H solution for 53 min in group 5-HD+ P.The heart rate (HR), left ventricular developed pressure (LVDP), left ventricular end-diastolic pressure (LVEDP) and the maximum rate of increase in left ventricular pressure (+ dp/dtmax) were recorded at 20 min of equilibration (T1) and at the end of reperfusion(T2). Myocardial tissues were obtained at T2 for determination of myocardial infarct size and for examination of myocardial ultrastructure and Flameng scoring of the mitochondria was performed. Results Compared with group C, the HR, LVDP and + dp/dtmax were significantly decreased, and the LVEDP, myocardial infarct size and mitochondrial Flameng score were increased at T2 in group I/R (P 0.05). Compared with group P, the HR, LVDP and + dp/dtmax were significantly decreased and the LVEDP, myocardial infarct size and mitochondrial Flameng score were increased at T2 (P<0.05), and the pathological changes of myocardium were accentuated in group 5-HD+ P. Conclusion The whole mechanism by which pinacidil postconditioning reduces myocardial I/R injury is related to promoting opening of mito-KATP channel in rats. Key words: Myocardial reperfusion injury; Pinacidil; Mitochondria; KATP channels

Role of μ opioid receptor in morphine preconditioning-induced reduction of myocardial ischemia-reperfusion injury in rats with chronic heart failure: an in vitro experiment

Objective To evaluate the role of μ opioid receptor in morphine preconditioning-induced reduction of myocardial ischemia-reperfusion (I/R) injury in rats with chronic heart failure. Methods Adult male Sprague-Dawley rats, weighing 170-230 g, in which chronic heart failure was induced by injecting doxorubicin via the tail vein, were studied.The rats were sacrificed and their hearts were excised and perfused in a Langendorff apparatus with K-H solution saturated with 95% O2-5% CO2 at 37 ℃.Forty isolated rat hearts with I/R injury were randomly divided into 4 groups (n=10 each): group I/R, morphine preconditioning group (group MP), μ opioid receptor antagonist CTOP plus morphine preconditioning group (group CTOP+ MP) and CTOP group.Myocardial I/R was induced by occlusion of the left coronary artery for 30 min followed by 120 min of reperfusion.In group MP, the hearts were perfused with K-H solution for 15 min, with K-H solution containing 1 μmol/L morphine for 5 min and with K-H solution for 5 min, 3 cycles in total, and then the model of myocardial I/R was established.The hearts were perfused with K-H solution containing 1 μmol/L CTOP starting from 10 min before morphine preconditioning until 5 min of ischemia in group CTOP+ MP.The hearts were perfused with K-H solution containing 1 μmol/L CTOP starting from 40 min before ischemia until 5 min of ischemia in group CTOP.The coronary effluent was collected at 15 min of equilibration (baseline) and 5 and 10 min of reperfusion to detect the activity of lactate dehydrogenase (LDH). Myocardial infarct size (IS) and the area at risk (AAR) were measured by 2, 3, 5-triphenyl-tetrazolium staining, and IS/AAR percentage was calculated.The expression of Bcl-2 and Bax mRNA was determined using uantitative real-time polymerase chain reaction, and the ratio of Bcl-2/Bax was calculated. Results Compared with group I/R, the IS and IS/AAR percentage were significantly decreased, the activity of LDH in coronary effluent was decreased, the expression of Bax mRNA was down-regulated, the expression of Bcl-2 mRNA was up-regulated, and the Bcl-2/Bax ratio was increased in group MP (P 0.05). Compared with group MP, the IS and IS/AAR percentage were significantly increased, the activity of LDH in coronary effluent was increased, the expression of Bax mRNA was up-regulated, the expression of Bcl-2 mRNA was down-regulated, and the Bcl-2/Bax ratio was decreased in group CTOP+ MP (P<0.05). Conclusion The mechanism by which morphine preconditioning reduces myocardial I/R injury may be related to activating μ opioid receptors and thus maintaining the balance between Bcl-2 and Bax gene expression in the rats with chronic heart failure. Key words: Morphine; Receptors, opioid, mu; Heart failure; Myocardial reperfusion injury

Effect of diabetes mellitus on adenosine postconditioning-induced reduction of myocardial ischemia-reperfusion injury in rats

Objective To investigate the effect of diabetes mellitus (DM) on adenosine postconditioning-induced reduction of myocardial ischemia-reperfusion (I/R) injury in rats. Methods Adult male Sprague-Dawley rats, weighing 230-260 g, were used in the study.Type 2 DM was induced by high-fat diet and intraperitoneal l% streptozocin 35 mg/kg and confirmed by fasting blood glucose concentration>16.7 mmol/L 72 h later.Eighteen rats with type 2 DM were divided into 3 groups (n=6 each) using a random number table: sham operation group (DS group), I/R group (DI/R group) and adenosine postconditioning group (DAP group). Eighteen healthy nondiabetic rats were selected and randomly divided into 3 groups (n=6 each): sham operation group (NS group), I/R group (NI/R group) and adenosine postconditioning group (NAP group). Myocardial I/R was induced by 30 min occlusion of the left anterior descending branch of coronary artery followed by 2 h of reperfusion.Venous blood samples were collected from the femoral vein at 2 h of reperfusion for measurement of plasma cardiac troponin I (cTnI) and creatine kinase-MB (CK-MB) concentrations (by enzyme-linked immunosorbent assay). The rats were then sacrificed immediately after blood sampling for determination of the myocardial ischemic area and infarct size. Results The plasma cTnI and CK-MB concentrations were significantly increased, and the percentage of myocardial infarct size was increased after myocardial I/R in nondiabetic and diabetic rats.Adenosine postconditioning significantly decreased plasma cTnI and CK-MB concentrations and percentage of myocardial infarct size in nondiabetic and diabetic rats (P<0.05). Compared with group NAP, the plasma concentrations of cTnI and CK-MB were significantly increased, and the percentage of myocardial infarct size was increased in group DAP (P<0.05). Conclusion DM can weaken cardioprotection induced by adenosine postconditioning in rats. Key words: Diabetes mellitus; Adenosine; Ischemic postconditioning; Myocardial reperfusion injury

Liraglutide-induced reduction of myocardial ischemiareperfusion injury in rats via ERK1/2 signaling pathway

Purpose: To investigate the protective effect of liraglutide on myocardial ischemia reperfusion (I/R) injury and its molecular mechanism. Methods: Ischemia reperfusion model male Sprague-Dawley (SD) rats were randomly divided into negative control group, I/R group (saline), liraglutide group (liraglutide) and PD group (liraglutide + PD98059). The weight of myocardium in ischemic and infarction areas of the heart, myocardial injury biomarker, oxidative stress, as well as expressions of mRNA molecules of apoptosis were determined. Results: The myocardial mass of ischemic and infarcted areas of the heart (relative to left ventricular mass) of I/R group were significantly higher ( p ˂ 0.05) than those of negative control group, but significantly lower in liraglutide group than in I/R group ( p > 0.05). However, the parameters were significantly higher in PD group than in liraglutide group ( p ˂ 0.05). CK, CK-MB and LDH activities, as well as levels of cTnI and cTnT in I/R group were significantly higher ( p ˂ 0.05) than those of negative control group. However, the parameters were significantly lower ( p ˂ 0.05) in liraglutide group than in I/R group, but higher in PD group ( p ˂ 0.05) than in liraglutide group. Serum SOD, GSH-Px, CAT activities and tBcl-2 mRNA expression were significantly lower in I/R group than those of negative control group ( p ˂ 0.001), while those PD group were significantly lower than those of liraglutide group ( p ˂ 0.001). Conclusion: Liraglutide alleviates myocardial ischemia-reperfusion injury and inhibits oxidative stress and apoptosis via ERK1/2 signaling pathway in rats, but further studies are required to ascertain the clinical efficacy and safety of the compound. Keywords: Ischemia-reperfusion injury, Liraglutide, ERK1/2 signal pathway, Oxidative stress, Apoptosis

Role of hypoxia-inducible factor-1α in sevoflurane postconditioning-induced reduction of myocardial ischemia-reperfusion injury in mice

Objective To evaluate the role of hypoxia-inducible factor-1α(HIF-1α) in sevoflurane postconditioning-induced reduction of myocardial ischemia-reperfusion (I/R) injury in mice. Methods Forty pathogen-free healthy male C57 mice, aged 8 weeks, weighing 20-30 g, were assigned into 4 groups (n=10 each) using a random number table: sham operation group(group Sham), myocardial I/R group (group I/R), sevoflurane postconditioning group (group SPC) and HIF-1α inhibitor 2Me2 group (group 2Me2). Myocardial I/R was induced by occlusion of the left anterior descending branch of the coronary artery for 30 min followed by 120 min of reperfusion in pentobarbital sodium-anesthetized mice.In group SPC, 3% sevoflurane was inhaled for 15 min starting from the onset of reperfusion.In group 2Me2, 30% 2Me2 (30 mg/kg) was intraperitoneally injected at 30 min before ischemia.The mice were sacrificed at the end of reperfusion, and the hearts were removed for determination of the myocardial infarct size (using the Image J software) and expression of HIF-1α in the nucleus of cardiomyocytes (by Western blot). Results Compared with group Sham, the myocardial infarct size was significantly increased in I/R, SPC and 2Me2 groups, the expression of HIF-1α was significantly up-regulated in I/R and SPC groups, and the expression of HIF-1α was significantly down-regulated in group 2Me2 (P<0.05). Compared with group I/R, the myocardial infarct size was significantly decreased, and the expression of HIF-1α was up-regulated in group SPC, and the myocardial infarct size was significantly increased, and the expression of HIF-1α was down-regulated in group 2Me2 (P<0.05). Compared with group SPC, the myocardial infarct size was significantly increased, and the expression of HIF-1α was down-regulated in group 2Me2 (P<0.05). Conclusion The mechanism by which sevoflurane postconditioning reduces myocardial I/R injury is related to up-regulation of HIF-1α expression in mice. Key words: Hypoxia-inducible factor 1, alpha subunit; Anesthetics, inhalation; Myocardial reperfusion injury; Ischemic postconditioning

Role of mitochondrial ATP-sensitive potassium channel in reduction of myocardial ischemia-reperfusion injury by calcitonin gene-related peptide in rats: an in vitro experiment

Objective To evaluate the role of the mitochondrial ATP-sensitive potassium (mito-KATP) channel in reduction of myocardial ischemia-reperfusion (I/R) injury by calcitonin gene-related peptide (CGRP) in rats in an in vitro experiment. Methods Healthy adult male Sprague-Dawley rats, weighing 250-300 g, were used in this study.After the animals were anesthetized, their hearts were immediately removed and retrogradely perfused with oxygenated K-H solution at 37 ℃ in a Langendorff apparatus.Twenty-four isolated rat hearts were assigned into 4 groups (n=6 each) using a random number table: control group (C group), I/R group, CGRP group and 5-hydroxydecanoate (5-HD) group.The hearts were first perfused with K-H solution for 30 min in the three groups.The hearts were continuously perfused with K-H solution for 150 min in group C. The hearts were subjected to ischemia for 30 min followed by 120 min of reperfusion to establish the model of myocardial I/R injury.In group CGRP, after the hearts were perfused with K-H solution for 10 min, 10-8 mol/L CGRP was infused for 20 min at a rate of 0.5 ml/min via the aorta, and then the model of myocardial I/R injury was established.In 5-HD group, specific mito-KATP channel blocker 5-HD 100 μmol/L was infused for 10 min at a rate of 0.5 ml/min via the aorta, and the other treatments were similar to those previously described in CGRP group.At the end of equilibration and 30, 60, 90 and 120 min of reperfusion, heart rate (HR), 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.The myocardial infarct size was measured by 2, 3, 5-triphenyltetrazolium chloride staining at 120 min of reperfusion. Results Compared with C group, HR, LVSP and ±dp/dtmax were significantly decreased and LVEDP was increased during reperfusion, and the percentage of myocardial infarct size was increased at 120 min of reperfusion in the other three groups (P<0.05). Compared with I/R group, HR, LVSP and ±dp/dtmax were significantly increased and LVEDP was decreased during reperfusion, and the percentage of myocardial infarct size was decreased at 120 min of reperfusion in CGRP group (P<0.05). Compared with CGRP group, HR, LVSP and ±dp/dtmax were significantly decreased and LVEDP was increased during reperfusion, and the percentage of myocardial infarct size was increased at 120 min of reperfusion in 5-HD group (P<0.05). Conclusion Opening of mito-KATP channels is involved in CGRP-induced reduction of myocardial I/R injury in rats in an in vitro experiment. Key words: Calcitonin gene-related peptide; Myocardial reperfusion injury; Mitochondria; KATP channels

Role of PI3K/Akt or JAK/STAT-3 signaling pathways in reduction of myocardial ischemia-reperfusion injury by combination of limb ischemic and morphine postconditioning in rats

Objective To evaluate the role of the phosphatidylinositol 3-kinase(PI3K)/protein kinase B(Akt)or Janus kinase(JAK)/signal transducer and activator of transcription 3(STAT-3)signaling pathways in reduction of myocardial ischemia-reperfusion(I/R)injury by combination of limb ischemic and morphine postconditioning in rats. Methods Eighty SPF healthy male Sprague-Dawley rats, aged 8 weeks, weighing 280-320 g, were used in the study.Myocardial I/R was induced by occlusion of the left anterior descending branch of the coronary artery for 30 min followed by 120 min reperfusion.The rats were divided into 8 groups(n=10 each)using a random number table: I/R group, limb ischemic postconditioning group(LIP group), morphine postconditioning group(group MP), combination of limb ischemic and morphine postconditioning group(LIP+ MP group)and signaling pathway blocker groups(I/Rb group, LIPb group, MPb group, LIP+ MPb group). In I/R, LIP, MP and LIP+ MP groups, the animals were sacrificed at the end of reperfusion, and myocardial specimens in ischemic and non-ischemic regions were obtained for determination of phosphorylated STAT-3(p-STAT-3), STAT-3, phosphorylated Akt(p-Akt)and Akt expression(by Western blot)and STAT-3 and Akt mRNA expression(by polymerase chain reaction). In I/Rb, LIPb, MPb and LIP+ MPb groups, PI3K/Akt signaling pathway blocker LY294002 0.3 mg/kg was intravenously injected in 5 rats of each group, and JAK/STAT-3 signaling pathway blocker AG490 5 mg/kg was intravenously injected in the other 5 rats of each group.The animals were sacrificed at the end of reperfusion, and myocardial specimens in the ischemic region were obtained for determination of myocardial infarct size. Results Compared with I/R group, the p-STAT-3/STAT-3 ratio in LIP, MP and LIP+ MP groups and p-Akt/Akt ratio in LIP+ MP group were significantly increased, and the expression of STAT-3 and Akt mRNA was up-regulated in LIP+ MP group(P 0.05). When JAK2 inhibitor AG490 was applied, the myocardial infarct size was significantly smaller in LIP+ MPb group than in I/Rb, LIPb and MPb groups(P 0.05). Conclusion Combination of limb ischemic and morphine postconditioning can enhance the activation of PI3K/Akt or JAK/STAT-3 signaling pathways, and the cardioprotection is dependent on the integrity of the PI3K/Akt signaling pathway and partially dependent on the integrity of the JAK/STAT-3 signaling pathway when applied in combination in rats. Key words: 1-Phosphatidylinositol 3-kinase; Protein-tyrosine kinases; Extremities; Morphine; Myocardial reperfusion injury; Postconditioning

Role of p38MAPK signaling pathway in reduction of myocardial ischemia-reperfusion injury by morphine preconditioning in rats with chronic heart failure in vitro

Objective To investigate the role of p38 mitogen-activated protein kinase (p38MAPK) signaling pathway in reduction of myocardial ischemia-reperfusion (I/R) injury by morphine preconditioning in the rats with chronic heart failure in vitro. Methods Adult male Sprague-Dawley rats, weighing 200-230 g, aged 6-7 weeks, in which doxorubicin 2 mg/kg was injected via the tail vein once a week for 6 consecutive weeks to induce chronic heart failure, were studied.At the end of 8th week, 30 rats with chronic heart failure were randomly divided into 5 groups (n=6 each) using a random number table: sham operation group (group Sham), I/R group, morphine preconditioning group (group MPC), SB203580 (p38MAPK inhibitor) + morphine preconditioning group (group SBM), and SB203580 group (group SB). The hearts were quickly excised and passively perfused in a Langendorff apparatus and subjected to 30 min of occlusion of the anterior descending branch of the left coronary artery followed by 120 min of reperfusion to establish the model of myocardial I/R injury.After equilibration, the hearts were subjected to 3 cycles of 5 min perfusion with K-H solution containing morphine 1 μmol/L at 5-min intervals before ischemia in group MPC.In group SBM, the hearts were perfused with K-H solution containing SB203580 (5 μmol/L) for 45 min starting from 10 min before morphine preconditioning until 5 min of ischemia.In group SB, morphine preconditioning was not performed, and the hearts were only perfused with K-H solution containing SB203580 (5 μmol/L) starting from 40 min before ischemia until 5 min of ischemia.At 15 min of equilibration (baseline), 5 and 10 min of reperfusion, the coronary effluent was collected to detect the activity of lactate dehydrogenase (LDH) using the chemical colorimetry.At 10 min of reperfusion, the expression of phosphor-p38MAPK (p-p38MAPK) in the myocardium was determined by Western blot in Sham, I/R and MPC groups.At 120 min of reperfusion, the area at risk (AAR), total areas of right and left ventricles (LV+ RV), and infarct size (IS) were measured, and the IS/AAR ratio was calculated. Results Compared with group Sham, the LDH activity in coronary effluent during reperfusion and IS/AAR ratio were significantly increased in the other groups, and the expression of p-p38MAPK was significantly up-regulated in I/R and MPC groups (P 0.05). Compared with group MPC, the LDH activity in coronary effluent during reperfusion was significantly increased, and the IS and IS/AAR ratio were significantly increased in group SBM (P<0.05). Conclusion The mechanism by which morphine preconditioning reduces myocardial I/R injury is related to activation of p38MAPK signaling pathway in the rats with chronic heart failure in vitro. Key words: p38 Mitogen-activated protein kinases; Heart failure; Myocardial reperfusion injury; Morphine; Ischemic preconditioning

Mechanical tissue resuscitation (MTR): a nonpharmacological approach to treatment of acute myocardial infarction.

Myocardial ischemia-reperfusion injury is known to trigger an inflammatory response involving edema, apoptosis, and neutrophil activation/accumulation. Recently, mechanical tissue resuscitation (MTR) was described as a potent cardioprotective strategy for reduction of myocardial ischemia-reperfusion injury. Here, we further describe the protective actions of MTR and begin to define its therapeutic window. A left ventricular, free-wall ischemic area was created in anesthetized swine for 85 minutes and then reperfused for three hours. Animals were randomized to two groups: (1) untreated controls (Control) and (2) application of MTR that was delayed 90 minutes after the initiation of reperfusion (D90). Hemodynamics and regional myocardial blood flow were assessed at multiple time points. Infarct size and neutrophil accumulation were assessed following the reperfusion period. In separate cohorts, the effect of MTR on myocardial interstitial water (MRI imaging) and blood flow was examined. Both groups had similar areas at risk (AAR), hemodynamics, and arterial blood gas values. MTR, even when delayed 90 minutes into reperfusion (D90, 29.2 ± 5.0% of AAR), reduced infarct size significantly compared to Controls (51.9 ± 2.7%, p = 0.006). This protection was associated with a 33% decrease in neutrophil accumulation (p = 0.047). Improvements in blood flow and interstitial water were also observed. Moreover, we demonstrated that the therapeutic window for MTR lasts for at least 90 minutes following reperfusion. This study confirms our previous observations that MTR is an effective therapeutic approach to reducing reperfusion injury with a clinically useful treatment window.

Role of Nrf2/ARE signaling pathway in reduction of myocardial ischemia-reperfusion injury by propofol in rats

Objective To evaluate the role of nuclear factor erythroid 2-related factor 2/antioxidant responsive element (Nrt2/ARE) signaling pathway inthe reduction of myocardial ischemia-reperfusion (I/R) injury by propofol in rats.Methods Sixty adult male Sprague-Dawley rats,weighing 200-240 g,were randomly divided into 5 groups (n =12 each) using a random number table:sham operation group (S group),I/R group,propofol group (P group),propofol + Nrf2 vehicle-plasmid group (PNV group) and propofol + Nrf2 siRNA plasmid group (PNS group).The animals were anesthetized with inhalation of 2％ isoflurane,tracheally intubated and mechanically ventilated.Myocardial I/R was produced by 5 min occlusion of left anterior descending branch of coronary artery followed by 60 min reperfusion.In P,PNV and PNS groups,isoflurane inhalation was stopped after successful intubation and propofol was infused via the caudal vein at 6 mg· kg-1 · h-1 until 30 of reperfusion.At 30 min of propofol infusion,Nrf2 vehicle-plasmid 10 μg (100 μl) was injected intramyocardially before myocardial ischemia in group PNV,and Nrf2 siRNA 10 μg (100 μl) was injected intramyocardially before myocardial ischemia in group PNS.The animals were sacrificed at 60 min of reperfusion and myocardial specimens were taken for determination of the infarct size,apoptosis index,and the expression of Nrf2 and heme oxygenase-1 (HO-1).Results Compared with group S,the infarct size and apoptosis index were significantly increased,and the expression of Nrf2 and HO-1 was up-regulated in I/R and P groups.Compared with group I/R,the infarct size and apoptosis index were significantly decreased,and the expression of Nrf2 and HO-1 was up-regulated in group P.Compared with group P,no significant changes were found in the infarct size,apoptosis index and expression of Nrf2 and HO-1 in group PNV,and the infarct size and apoptosis index were significantly increased,and the expression of Nrf2 and HO-1 was down-regulated in group PNS.Conclusion Nrf2/ARE signaling pathway is involved in the reduction of myocardial I/R injury by propofol in rats. Key words: Propofol ; Myocardial reperfusion injury ; NF-E2-related factor 2 ; Response elements

Autofluorescence spectroscopy for NADH and flavoproteins redox state monitoring in the isolated rat heart subjected to ischemia-reperfusion

Reduction of myocardial ischemia-reperfusion injury in the patients undergoing cardiac surgery under cardiopulmonary bypass represents an important goal. Intraoperative monitoring of myocardial metabolic state using continuous registration of nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD) fluorescence might contribute to the solution of the problem. The successful application of fluorescent spectroscopy in the clinical field requires additional refinement of the technique, particularly using excitation of both NADH and FAD with different wavelengths. The experiments were performed on the isolated Langendorff-perfused rat hearts (n=28) subjected to either regional or global ischemia-reperfusion. Two principles of NADH and FAD autofluorescence (AF) measurement were used for ischemia monitoring: (1) analysis of photographs and videos obtained with multispectral organoscopy technique allowing the assessment of both spatial and temporal characteristics of the process (n=16); (2) continuous registration of tissue redox state in a representative area of the heart by application of local spectroscopy, assisted by fiber optic spectrometer (n=12). It was found that regional myocardial ischemia resulted in a rapid, substantial increase in the intensity of NADH AF excited at 360nm in the ischemic versus non-ischemic area of the heart. The same result was obtained when the heart was made globally ischemic, while the restoration of perfusate flow completely reversed the increase in NADH AF. During the transition from ischemia to reperfusion, the spatial heterogeneity of myocardial AF was noted on video recordings, probably reflecting the microheterogeneity of myocardial blood flow. Local spectroscopy studies demonstrated opposite changes in the NADH and FAD AF during ischemia. Using both methodological approaches, we found that repetitive brief episodes of global myocardial ischemia resulted in progressive decrease in the magnitude of AF elevation, which might point to preconditioning effect. The application of multispectral fluorescent organoscopy offers the advantage of monitoring myocardial redox state at the level of the entire heart. Local spectroscopy is characterized by better precision and, in addition, provides the unique opportunity to measure AF in different parts of the spectrum. AF measurements are non-invasive, rapid, and technically easy to perform. For future clinical applications, it might be recommended to combine the measurement of redox state of both NADH and FAD, using excitation wavelength and emission filter optimal for each fluorophore.

Role of PI3K/Akt signaling pathway in dexmedetomidine postconditioning-induced reduction of myocardial ischemia-reperfusion injury in rats

Objective To evaluate the role of phosphatidylinositol 3-kinase (PI3K)/protein-serinethreonine kinases (Akt) signaling pathway in dexmedetomidine postconditioning-induced reduction of myocardial ischemia-reperfusion (I/R) injury in rats.Methods Seventy-two healthy male Sprague-Dawley rats,aged 4-5 months,weighing 200-240 g,were heparinized and anesthetized with intraperitoneal pentobarbital sodium 40 mg/kg.Their hearts were rapidly excised and perfused in a Langendorff apparatus with oxygenated (95％ O2-5％ CO2) K-H solution at 0-4℃.The isolated hearts were randomly divided into 6 groups (n =12 each):control group (group C),group I/R,dexmedetomidine postconditioning group (gruop D),solvent group (group DMSO),PI3K inhibitor LY294002 group (group L) and LY294002 + dexmedetomidine postconditioning group (group L + D).After a 20 min stabilization period,the hearts were continuously perfused with K-H solution for 120 min in group C and were subjected to 30 min of global no-flow ischemia followed by 90 min of repeffusion in the other groups.Dexmedetomidine 100 nmo/L was added during the initial 30 min of reperfusion in D and L + D groups.LY294002 15 μmol/L was added in L group.0.02％ DMSO containing 15 μmol/L LY294002 was added in L + D group.0.02％ DMSO was added in DMSO group.HR,left ventricular end-diastolic pressure,left ventricular developed pressure and ± dp/dtmax were recorded at the end of 20 min stabilization and 15,30 and 90 min of reperfusion.The expression of phosphorylated Akt (p-Akt) and Akt was measured at 30 min of reperfusion.Myoeardial infarct size was determined using TTC staining at 90 min of reperfusion.Results Compared with group C,HR,left ventricular developed pressure and ± dp/dtmax were significantly decreased,and left ventricular enddiastolic pressure and myocardial infarct size were increased in the other 5 groups,and the expression of p-Akt was significantly up-regulated in group D (P ＜ 0.05).Compared with group I/R,HR was significantly decreased at 15 and 30 min of reperfusion,the expression of p-Akt was up-regulated,and myocardial infarct size was decreased in group D (P ＜ 0.05).Compared with group D,the expression of p-Akt was down-regulated,and myocardial infarct size and HR was increased in L + D group (P ＜ 0.05).Conclusion Dexmedetomidine postconditioning attenuates myocardial I/R injury throuth activating PI3K/Akt signaling pathway in rats. Key words: 1-PhosphatidyIinositol 3-kinase ; Protein-serine-threonine kinases ; Dexmedetomidine ; Myocardial reperfusion injury; Postconditioning

Rosuvastatin Reloading before Cardiac Surgery with Cardiopulmonary Bypass

Background/Purpose: Recent evidence suggests that statin-mediated cardioprotection after chronic statin therapy decreases over time and can be reactivated by preprocedural high-dose statin reloading therapy. We tested in a porcine cardiopulmonary bypass (CPB) model whether statin-related cardioprotection is further enhanced by a preoperative rosuvastatin reloading therapy. Methods: Control (n = 6), rosuvastatin-pretreated (n = 6; 20 mg/day for 7 days p.o.) and rosuvastatin-reloaded (n = 6; p.o. treatment plus 0.10 mg/kg/h i.v. during surgery) pigs (Deutsche Landrasse) were subjected to CPB for 2 h with 1 h of cardioplegic cardiac arrest. Systemic hemodynamics, cardiac index (CI), coronary blood flow (CBF) and left ventricular (LV) function [pressure-volume area (PVA), preload recruitable stroke work (PRSW)] were determined before and 4 h after CPB. Myocardial expression (PCR) and protein content (Western blot) of endothelial NO synthase (eNOS) and phosphatase and tensin homolog deleted on chromosome ten (PTEN) were measured, and right coronary relaxation was assessed postmortem. All data are given as mean ± SD. Results: Preoperative plasma LDL, HDL and cholesterol did not differ between treatment groups. Compared to control, oral treatment improved post-CPB CI, CBF, first derivative of maximal LV-pressure (LVdp/dt) and PVA (p < 0.05). Significant enhancement was achieved with perioperative reloading therapy (CI: 5.2 ± 1.0 vs. 3.9 ± 1.5 l/min/m²; CBF: 76 ± 32 vs. 43 ± 8 ml/min; LVdp/dt: 1,980 ± 333 vs. 1,249 ± 461 mm Hg/s; PVA: 6,954 ± 941 vs. 3,252 ± 1,822 mm Hg·ml; p < 0.05) with improved in vitro NO-dependent coronary relaxation (102 ± 10 vs. 79 ± 14%; p = 0.003). Irrespective of recapture therapy statin pretreatment augmented myocardial eNOS and PTEN (p < 0.05), but failed to increase cardiac eNOS or PTEN expression after CPB. Conclusions: Periprocedural statin reloading therapy enhances myocardial and coronary function after cardiac surgery with CPB and may therefore provide a valuable therapeutic approach for the reduction of myocardial ischemia-reperfusion injury.

Role of signal transducer and activator of transcription 3 signaling pathway in reduction of myocardial ischemia-reperfusion injury by diazoxide postconditioning in rats

Objective To evaluate the role of signal transducer and activator of transcription 3 (STAT3) signaling pathway in the reduction of myocardial ischemia-reperfusion (I/R) injury by diazoxide postconditioning in rats.Methods Sixty adult male Sprague-Dawley rats,aged 3 months,weighing 240-260 g,were randomly divided into 5 groups (n =12 each):sham operation group (S group),I/R group,vehicle group (V group),diazoxide postconditioning group (D group),and STAT3 signaling pathway inhibitor Stattic group (St group).Myocardial I/R was produced by 30 min occlusion of left anterior descending branch of coronary artery followed by 120 min reperfusion.In V and D groups,0.4％ dimethyl sulfoxide and 7 mg/kg diazoxide (in 1 ml of 0.4％ dimethyl sulfoxide) were injected through the femoral vein at the onset of reperfnsion,respetively.In St group,Stattic was injected through the femoral vein 10 min before reperfusion,and the other procedures were the same as those in D group.The infarct size (IS) and myocardial apoptosis were detected by TTC staining and TUNEL,respectively.Apoptotic index (AI) was calculated.STAT3 mRNA expression in myocardial tissues was detected using RT-PCR.Western blot was used to detect the phosphorylation of STAT3.Results Compared with S group,the IS and AI were significantly increased and the expression of STAT3 mRNA and phosphorylation of STAT3 were decreased in I/R group (P ＜ 0.05).Compared with I/R group,the IS and AI were significantly decreased and the expression of STAT3 mRNA and phosphorylation of STAT3 were increased in D group (P ＜ 0.05).There was no significant difference in IS,AI,expression of STAT3 mRNA and phosphorylation of STAT3 between V group and St group (P ＞0.05).Compared with group D,the IS and AI were significantly increased and the expression of STAT3 mRNA and phosphorylation of STAT3 were decreased in St group (P ＜ 0.05).Conclusion STAT3 signaling pathway is involved in the reduction of myocardial I/R injury by diazoxide postconditioning in rats. Key words: STAT3 transcription factor; Diazoxide ; Myocardial reperfusion injury; Apoptosis

Roles of reactive oxygen species in the reduction of myocardial ischemia-reperfusion injury by fentanyl postconditioning and remote limb ischemic postconditioning in rats

Objective To investigate the role of reactive oxygen species (ROS) in the reduction of myocardial ischemia-reperfusion (I/R) injury by fentanyl postconditioning and remote limb ischemic postconditioning in rats.Methods Sixty-three male Sprague-Dawley rats,aged 8 weeks,weighing 250-350 g,were equally and randomly allocated into 7 groups:sham operation group (group S),group I/R,fentanyl postconditioning group (group F),remote limb ischemic postconditioning group (group R),ROS scavenger N-(2-Mercaptopropionyl) glycine (MPG) group (group M),MPG + fentanyl postconditioning group (group MF),and MPG + remote limb ischemic postconditioning group (group MR).Myocardial I/R was induced by occlusion of anterior descending branch of left coronary artery for 30 min followed by 180 min of reperfusion.In group S the anterior descending branch was only exposed but not ligated.MPG 5 mg/kg was infused intravenously from 5 min before ischemia to 15 min of reperfusion in groups M,MF and MR,while the equal volume of normal saline was given in the other four groups.In groups F and MF,fentanyl 30 μg/kg was injected intravenously at 15 min of myocardial ischemia.In groups R and MR,the animals underwent 10 min ischemia of bilateral hind limbs starting from 15 min of myocardial ischemia.Arterial blood samples were taken at 180 min of reperfusion to determine the serum cardiac troponin I (cTnI) concentration.The rats were then sacrificed.The infarct size was measured by TTC.Results Compared with group S,the serum cTnI concentration and infarct size were significantly increased in the other six groups (P ＜0.05).Compared with group I/R,no significant change was found in the serum cTnI concentration and infarct size in M group,and the serum cTnI concentration and infarct size were significantly decreased in F and R groups (P ＜ 0.05).There was no significant difference in the serum cTnI concentration and infarct size between MF group and F group (P ＞ 0.05).The serum cTnI concentration was significantly higher and the infarct size was larger in group MR than in group R (P ＜ 0.05).Conclusion ROS is involved in the reduction of myocardial I/R injury by remote limb ischemic postconditioning in rats,but not in the myocardial protection provided by fentanyl postconditioning. Key words: Reactive oxygen species; Fentanyl ; Lower extremity ; Myocardial reperfusion injury; Ischemic postconditioning

Role of inducible nitric oxide synthase in reduction of myocardial ischemia-reperfusion injury by sufentanil preconditioning in rats

Objective To investigate the role of inducible nitric oxide synthase (iNOS) in reduction of myocardial ischemia-reperfusion (I/R) injury by sufentanil preconditioning in rats. Methods Thirty adult male SD rats, weighing 250-330 g, were randomly divided into 5 groups ( n =6 each): sham operation group (group S),I/R group, sufentanil preconditioning group (group SF), sufentanil preconditioning + a specific inhibitor of iNOS S-methyl thiourea (SMT) group (group SF+ SMT) and S-methyl thiourea group (group SMT). In I/R,SF,SF+SMT and SMT groups, myocardial I/R was produced by occlusion of left anterior descending coronary artery for 30 min followed by 120 min reperfusion. Group SF received 30 min infusion of sufentanil 120 μg/kg via caudal vein 24 h before ischemia. Group SF + SMT received infusion of sufentanil 120 μg/kg via caudal vein 24 h before ischemia and then SMT 10 mg/kg was injected 10 min before ischemia. In group SMT, SMT 10 mg/kg was injected 10min before ischemia. MAP and HR were recorded at 30 min before ischemia, at 30 min of ischemia and at the end of reperfusion. The rate-pressure product (RPP) was calculated. Arterial blood samples were obtained immediately at the end of reperfusion to determine the plasma concentration of NO. Then the animals were sacrificed and myo cardial tissues were obtained to determine the area at risk (AAR), infarct size (IS) and iNOS expression. IS/AAR was calculated. Results Compared with group S, MAP and RPP were significantly decreased, while IS/AAR was significantly increased at 120 min of reperfusion in the other four groups, and MAP and RPP were significantly decreased at 30 min of ischemia in I/R and SMT groups ( P ＜ 0.05). Compared with group I/R, no significant change was found in HR, MAP and RPP in SF, SF + SMT and SMT groups, and in IS/AAR and plasma NO concentrations in SF + SMT and SMT groups ( P ＞ 0.05), but IS/AAR was significantly decreased, and the plasma NO concentration and iNOS expression were significantly increased in group SF ( P ＜ 0. 05). Conclusion iNOS is involved in reduction of myocardial I/R injury by sufentanil preconditioning in rats. Key words: Nitric oxide synthase; Sufentanil; Ischemia preconditioning, myocardial; Myocardial reperfusion injury

Role of NO in reduction of myocardial ischemia-reperfusion injury by ginsenoside Rb1 preconditioning in diabetic rats

Objective To evaluate the role of by NO in reduction of myocardial ischemia-reperfusion （IR）injury by ginsenoside Rb1 preconditioning in diabetic rats. Methods Forty healthy adult male SD rats weighing 220-280 g were used in this study. Diabetes mellitus was induced by intraperitoneal streptozotocin 65 mg/kg and confirmed by fasting blood glucose 〉 16.7 mmol/L. The animals were randomly divided into 4 groups （ n = 10each）： sham operation group （group S）, group IR, ginsenoside Rb1 group （group R） and L-NAME ＋ ginsenoside Rb1 group （group LR）. IR was produced by occlusion of the anterior descending branch of left coronary artery （LAD） for 30 min followed by 120 min reperfusion in group IR, R and LR. In group S, LAD was exposed but not occluded. In group LR, L-NAME 10 mg/kg was injected iv 25 min before ischemia. In group R and LR, ginsenoside Rb1 40 mg/kg was injected iv 10 min before ischemia. In group S and IR, eaqual volume of normal saline was injected instead of ginsenoside Rb1. The blood sample was taken from carotid artery at 120 min of reperfusion for determination of serum activities of creatine kinase （CK） and lactate dehydrogenase （LDH）. Then the animals were sacrificed and myocadial tissues were obtained for determination of infarct size, endothelial nitric oxide synthase （eNOS） expression, MDA and NO contents, SOD activity and microscopic examination. Results The serum activities of CK and LDH were significantly increased and the myocardial infarct size was enlarged in group IR, R and LR, and eNOS expression was significantly down-regulated, MDA content was increased, and SOD activity and NO content was significantly decreased in group IR and LR compared with group S （ P 〈 0.05）. The serum activities of CK and LDH, and MDA content were significantly decreased, the myocardial infarct size was reduced, the expression of eNOS was up-regulated and the activity of SOD was increased in group R compared with group IR and LR （ P 〈 0.05）. There was no significant difference in the indices mentioned above between group IR and LR （ P〉 0.05）. Conclusion Ginsenoside Rb1 preconditioning can attenuate myocardial IR injury in diabetic rats via activation of eNOS, increase in NO production, and inhibition of the lipid peroxidation reaction. Key words: Nitric oxide; Ginsenosides; Ischemic preconditioning; Diabetes mellitus; Myocardial reperfusion injury

Reduction of Myocardial Ischemia-Reperfusion Injury by Mechanical Tissue Resuscitation Using Sub-Atmospheric Pressure

Reperfusion-induced injury after myocardial infarction is associated with a well-defined sequence of early and late cardiomyocyte death. Most present attempts to ameliorate this sequence focus on a single facet of the complex process in an attempt to salvage cardiomyocytes. We examined, as proof of concept, the effects of mechanical tissue resuscitation (MTR) with controlled negative pressure on myocardial injury following acute myocardial infarction. Anesthetized swine were subjected to 75 minutes of left coronary artery occlusion and three hours of reperfusion. Animals were assigned to one of three groups: (A) untreated control; treatment of involved myocardium for 180 minutes of MTR with (B) -50 mmHg, or (C) -125 mmHg. All three groups were subjected to equivalent ischemic stress. Treatment of the ischemic area with MTR for 180 minutes significantly (p < 0.001) reduced infarct size (area of necrosis/area at risk) in both treatment groups compared to control: 9.3 +/- 1.8% (-50 mmHg) and 11.9 +/- 1.2% (-125 mmHg) versus 26.4 +/- 2.1% (control). Total area of cell death was reduced by 65% with -50 mmHg treatment and 55% in the -125 mmHg group. Treatment of ischemic myocardium with MTR, for a controlled period of time during reperfusion, successfully reduced the extent of myocardial death after acute myocardial infarction. These data provide evidence that MTR using subatmospheric pressure may be a simple, efficacious, nonpharmacological, mechanical strategy for decreasing cardiomyocyte death following myocardial infarction, which can be delivered in the operating room.

Reduction of Myocardial Ischemia-Reperfusion Injury with Pre- and Postconditioning: Molecular Mechanisms and Therapeutic Targets

Reduction of infarct size as well as alleviation of other ischemia- and reperfusion-associated injuries are the goals of primary importance in cardiology. One of the remedies is considered to be myocardial preconditioning (PreCon) referred usually to as an increased myocardial tolerance to prolonged ischemia following brief ischemic or non-ischemic challenge. In this review, PreCon stimuli tested to date are considered including a number of mildly noxious factors applied either locally to the myocardium or systemically. Recently, one more mode of heart protection against reperfusion injury termed postconditioning (PostCon) has been developed. On the basis of ample evidence published, along with our findings, a detailed comparative analysis of PreCon and PostCon is presented, with special emphasis on the cellular, molecular, and pharmacological aspects of the topic as well as clinical applications, both implemented and awaiting practical approval.