Efecto del posacondicionamiento isquémico remoto sobre la fracción de eyección del ventrículo izquierdo en pacientes con infarto de miocardio con elevación del segmento ST sometidos a intervención coronaria percutánea primaria / Effect of remote ischemic postconditioning on left ventricular ejection fraction in patients with ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention

Resumen Antecedentes: En los pacientes con infarto agudo de miocardio con elevación del segmento ST (IAMCEST), el acondicionamiento isquémico puede ayudar a limitar la remodelación ventricular. Objetivos: Investigar el efecto del posacondicionamiento isquémico remoto (PAIR) en la función del ventrículo izquierdo durante la intervención coronaria percutánea primaria (ICPP) en pacientes con IAMCEST. Material y métodos: Estudio de intervención pre y posprueba con un total de 60 pacientes con IAMCEST. Los pacientes fueron divididos en dos grupos: con y sin PAIR. Resultados: En el seguimiento de seis meses se observó una diferencia significativa en la fracción de eyección del ventrículo izquierdo en pacientes con ICPP, la cual fue mayor en el grupo con PAIR en comparación con el grupo sin PAIR: 1.0 (−1.0 a 4.3) versus −1.0 (−4.0 a –1.3), p = 0.033. En la medición de seis meses, el volumen sistólico final del ventrículo izquierdo en los pacientes sin PAIR fue mayor en comparación con el grupo homólogo: 79.3 ± 30.5 mL versus 64.4 ± 21.4 mL, p = 0.032. Conclusiones: PAIR muestra efectos favorables en la función ventricular izquierda y, por lo tanto, en el futuro podría ser una estrategia cardioprotectora potencial contra la lesión por isquemia-reperfusión en pacientes con IAMCEST.

Abstract Background: Ischemic conditioning may help patients with ST-segment elevation myocardial infarction (STEMI) to limit ventricular remodeling. Objectives: To investigate the effect of remote ischemic postconditioning (RIPC) on left ventricular function during primary percutaneous coronary intervention (PPCI) in patients with STEMI. Material and methods: Pre- and post-test intervention study with a total of 60 STEMI patients. Patients were divided in two groups: with and without RIPC. Results: At 6-month follow-up evaluation, a significant difference in left ventricular ejection fraction was observed in patients who underwent PPCI, which was higher in the group with RIPC in comparison with the group without RIPC: 1.0 (−1.0 to 4.3) vs. −1.0 (−4.0 to –1.3), p = 0.033. In addition, at 6-month measurement, left ventricular end-systolic volume in patients without RIPC: was higher in comparison with their counterparts: 79.3 ± 30.5 mL versus 64.4 ± 21.4 mL, p = 0.032. Conclusions: RIPC shows favorable effects on left ventricular function and, therefore, in the future, it could be a potential cardioprotective strategy against ischemia-reperfusion injury in STEMI patients.

Ischemic Postconditioning Attenuates Myocardial Ischemia-Reperfusion-Induced Acute Lung Injury by Regulating Endoplasmic Reticulum Stress-Mediated Apoptosis

ABSTRACT Objective: To explore the effect of ischemic postconditioning on myocardial ischemia-reperfusion-induced acute lung injury (ALI). Methods: Forty adult male C57BL/6 mice were randomly divided into sham operation group (SO group), myocardial ischemia-reperfusion group (IR group), ischemic preconditioning group (IPRE group) and ischemic postconditioning group (IPOST group) (10 mice in each group). Anterior descending coronary artery was blocked for 60 min and then reperfused for 15 min to induce myocardial IR. For the IPRE group, 3 consecutive cycles of 5 min of occlusion and 5 minutes of reperfusion of the coronary arteries were performed before ischemia. For the IPOST group, 3 consecutive cycles of 5 min reperfusion and 5 minutes of occlusion of the coronary arteries were performed before reperfusion. Pathological changes of lung tissue, lung wet-to-dry (W/D) weight ratio, inflammatory factors, oxidative stress indicators, apoptosis of lung cells and endoplasmic reticulum stress (ERS) protein were used to evaluate lung injury. Results: After myocardial IR, lung injury worsened significantly, manifested by alveolar congestion, hemorrhage, structural destruction of alveolar septal thickening, and interstitial neutrophil infiltration. In addition, lung W/D ratio was increased, plasma inflammatory factors, including interleukin (IL)-6, tumor necrosis factor (TNF)-α, and IL-17A, were increased, malondialdehyde (MDA) activity of lung tissue was increased, and superoxide dismutase (SOD) activity was decreased after myocardial IR. It was accompanied by the increased protein expression levels of ERS-related protein glucose regulatory protein 78 (GRP78), CCAAT/enhancer-binding protein (C/EBP) homologous protein (CHOP), and caspase-12, and the increased apoptotic indices of lung tissues. Conclusion: IPOST can effectively improve myocardial IR-induced ALI by inhibiting ERS-induced apoptosis of alveolar epithelial cells.

Effects of local and remote ischemic postconditioning methods on ischemiareperfusion injury in a young animal model of acute mesenteric ischemia

Purpose: Acute mesenteric ischemia (AMI) is a condition in pediatric surgery that ranges from intestine necrosis to death. Ischemic postconditioning (IPoC) methods were developed to reduce the damage caused by revascularization. This study aimed to evaluate the efficacy of these methods in an experimental weaning rat model. Methods: Thirty-two 21-day-old Wistar rats were allocated into four groups according to the surgical procedure performed: control, ischemia-reperfusion injury (IRI), local (LIPoC) and remote IPoC (RIPoC). At euthanasia, fragments of the intestine, liver, lungs, and kidneys were submitted to histological, histomorphometric, and molecular analyses. Results: In the duodenum, intestines, and kidneys histological alterations promoted by IRI were reversed by remote postconditioning method. In the distal ileum, the histomorphometric alterations could be reversed by the postconditioning methods with more evident effects promoted by the remote method. The molecular analysis found that the levels of expression of Bax (proapoptotic) and Bcl-XL (antiapoptotic) genes in the intestine were increased by IRI. These alterations were equally reversed by the postconditioning methods, with more evident effects of the remote method. Conclusions: IPoC methods positively reduced the damage caused by IRI in weaning rats.

Effect of xenon post-conditioning on spinal cord ischemia/reperfusion injury in rats: regulating Akt signaling pathway and autophagy / 中国康复理论与实践

ObjectiveTo investigate the effect of xenon post-conditioning on autophagy after spinal cord ischemia/reperfusion injury (SCIRI) in rats and its relationship with protein kinase B (Akt) signaling pathway. MethodsA total of 30 male rats were randomized into sham-operated group (sham group), spinal cord ischemia/reperfusion injury group (I/R group) and I/R + xenon post-conditioning group (Xe group), with ten rats in each group. In the latter two groups, SCIRI was induced by clamping the abdominal aorta for 85 minutes followed by reperfusion for four hours. Xe group inhaled xenon and oxygen (1∶1) for one hour at one hour after initiation of reperfusion, while the other groups inhaled nitrogen and oxygen (1∶1) for one hour. After the reperfusion, they were assessed with Basso-Beattie-Bresnahan (BBB) scale and slanting board test. And then, their spinal cords of L3-5 were obtained. Nissl staining was used to count the number of normal neurons. Western blotting was used to detect the protein expression of Akt, p-Akt, p62, Beclin 1, microtubule-associated protein 1 light chain 3 (LC3) Ⅰ, LC3 Ⅱ. The mRNA expression of Beclin 1, p62 and LC3 Ⅱ in the spinal cord was measured with reverse transcription real-time quantitative polymerase chain reaction. ResultsCompared with the sham group, the BBB score and the maximum inclination of the slanting board test decreased, the count of normal neurons decreased, the protein expression of p62 and the p-Akt/Akt ratio decreased (P < 0.01), the protein and mRNA expression of Beclin 1 and LC3 Ⅱ, and the LC3 Ⅱ/LC3 Ⅰ ratio increased, the p62 mRNA expression decreased (P < 0.01) in the I/R group. Compared with the I/R group, the BBB score and the maximum inclination of the slanting board test increased, the count of normal neurons increased, the protein expression of p-Akt and p62 increased, the p-Akt/Akt ratio increased, the protein and mRNA expression of Beclin 1, LC3 Ⅱ and LC3 Ⅱ/LC3 Ⅰ ratio decreased, and the mRNA expression of p62 increased (P < 0.01) in Xe group. ConclusionXenon post-conditioning may relieve SCIRI in rats, which is related to activating Akt signaling pathway to inhibit autophagy.

Role of SIRT1/NLRP3 signaling pathway in sevoflurane postconditioning-induced attenuation of oxygen-glucose deprivation and restoration injury in HT22 cells / 中华麻醉学杂志

Objective:To evaluate the role of silent information regulator-1 (SIRT1)/nucleotide-binding domain (NOD)-like receptor protein-3 (NLRP3) signaling pathway in sevoflurane postconditioning-induced attenuation of oxygen-glucose deprivation and restoration (OGD/R) injury in mouse hippocampal neuronal cell line (HT22) cells.Methods:The HT22 cells were seeded in a culture plate (96-well plate, 100 μl/well; 6-well plate, 2 ml/well) at the density of 5×10 4 cells/ml or in a culture dish (6 cm in diameter) and then divided into 4 groups ( n=24 each) using a random number table method: control group (Control group), OGD/R group, sevoflurane postconditioning group (SPC group), and SIRT1 small interfering RNA group (si-SIRT 1 group). In Control group, cells were cultured at 37 ℃ in normal culture atmosphere. In OGD/R group, the culture medium was replaced with glucose-free serum-free culture medium, and cells were exposed to 95% N 2+ 5% CO 2 for 4 h in an incubator at 37 ℃, and then the glucose-free serum-free culture medium was replaced with the primary culture medium, and cells were cultured for 24 h at 37 ℃ in normal culture atmosphere. In SPC group, the glucose-free serum-free culture medium was replaced with the primary cell culture medium after 4-h oxygen and glucose deprivation, the cells were put into the hypoxia incubator chamber which was filled with 2% sevoflurane immediately after start of reoxygenation, then the chamber was placed in an incubator and the cells were cultured for 1 h at 37 ℃ in normal culture atmosphere, and finally the cells were removed from the chamber and cultured for 23 h at 37 ℃ in normal culture atmosphere. In si-SIRT1 group, SIRT1 small interfering RNA 150 pmol was added at 24 h before surgery, cells were then incubated, and the other procedures were the same as those previously described in group SPC. The cell survival rate was determined using MTT assay. TUNEL assay was used to detect cell apoptosis, and the apoptosis rate was calculated. The expression of SIRT1, NLRP3, IL-1β and IL-18 mRNA was determined using polymerase chain reaction. The expression of SIRT1, NLRP3, interleukin-1beta (IL-1β) and IL-18 was detected using Western blot. Results:Compared with Control group, the cell survival rate was significantly decreased, the apoptosis rate was increased, the expression of SIRT1 protein and mRNA was down-regulated, and the expression of NLRP3, IL-1β and IL-18 protein and mRNA was up-regulated in OGD/R group ( P<0.05). Compared with OGD/R group, the cell survival rate was significantly increased, the apoptosis rate was decreased, the expression of SIRT1 protein and mRNA was up-regulated, and the expression of NLRP3, IL-1β and IL-18 protein and mRNA was down-regulated in SPC group ( P<0.05). Compared with SPC group, the cell survival rate was significantly decreased, the apoptosis rate was increased, the expression of SIRT1 protein and mRNA was down-regulated, and the expression of NLRP3, IL-1β and IL-18 protein and mRNA was up-regulated in si-SIRT1 group ( P<0.05). Conclusions:Activation of SIRT1-NLRP3 signaling pathway is involved in sevoflurane postconditioning-induced attenuation of OGD/R injury in HT22 cells.

Role of succinate dehydrogenase in hypoxic postconditioning-induced reduction of hypoxia-reoxygenation injury in myocardial cells of rats and the relationship with mito-K ATP / 中华麻醉学杂志

Objective:To evaluate the role of succinate dehydrogenase (SDH) in hypoxic postconditioning (HPC)-induced reduction of hypoxia-reoxygenation (H/R) injury in myocardial cells of rats and the relationship with mitochondrial ATP-sensitive potassium channels (mito-K ATP). Methods:Myocardial cells isolated from adult male Sprague-Dawley rats were cultured for 48 h and then divided into 7 groups ( n=24 each) using a random number table method: blank control group (Nor group), H/R group, SDHA-siRNA adenovirus+ H/R group (siRNA+ H/R group), HPC group, SDHA-siRNA adenovirus+ HPC group (siRNA+ HPC group), 5-HD+ HPC group, and SDHA-siRNA adenovirus+ 5-HD+ HPC group (siRNA+ 5-HD+ HPC group). Nor group was continuously cultured for 195 min under normoxic conditions. The H/R injury model was prepared by exposing the cells to hypoxia for 45 min in 5% CO 2 + 1% O 2 + 94% N 2, followed by reoxygenation for 150 min. The HPC method involved three cycles of 5 min reoxygenation/5 min hypoxia at the end of 45 min ischemia before 120 min reoxygenation. The mito-K ATP blocker 5-HD administration method involved adding 5-HD at a final concentration of 100 μmol/L at 30 min of hypoxia. The myocardial cells in each siRNA group were successfully transfected with SDHA-siRNA adenovirus to silence SDHA expression. The cell viability, calcium ion level, SDH activity, ATP content, degree of mitochondrial permeability transition pore (mPTP) opening, and mitochondrial membrane potential (MMP) were measured at the end of reoxygenation. Results:Compared with Nor group, the cell viability, ATP content and MMP were significantly decreased, and the degree of mPTP opening, level of calcium ion and activity of SDH were increased in H/R group ( P<0.05). Compared with H/R group, the cell viability, ATP content and MMP were significantly increased, and the degree of mPTP opening, calcium ion level and SDH activity were decreased in siRNA+ H/R group and HPC group ( P<0.05). Compared with HPC group, the cell viability, ATP content and MMP were significantly decreased, and the degree of mPTP opening, calcium ion level and SDH activity were increased in 5-HD+ HPC group ( P<0.05), and the cell viability, ATP content and MMP were significantly increased, and the degree of mPTP opening, calcium ion level and SDH activity were decreased in siRNA+ HPC group ( P<0.05). Compared with siRNA+ HPC group, the cell viability, ATP content and MMP were significantly decreased, the opening degree of mPTP and calcium ion level were increased ( P<0.05), and no significant change was found in the SDH activity in siRNA+ 5-HD+ HPC group ( P>0.05). Compared with 5-HD+ HPC group, the SDH activity was significantly decreased, and no significant change was found in the other parameters in siRNA+ 5-HD+ HPC group ( P>0.05). Conclusions:HPC alleviates H/R injury probably by reducing SDH activity and opening mito-K ATP in myocardial cells of rats.

Role of reactive oxygen species in hypoxia postconditioning-induced activation of Nrf2/ARE signaling pathway in rat cardiomyocytes / 中华麻醉学杂志

Objective:To evaluate the role of reactive oxygen species (ROS) in hypoxia postconditioning-induced activation of nuclear factor erythroid 2-related factor 2 (Nrf2)/antioxidant response element (ARE) signaling pathway in rat cardiomyocytes.Methods:Primary cardiomyocytes of adult rats were isolated and cultured and divided into 4 groups ( n=20 each) using a random number table method: normal group (group N), hypoxia-reoxygenation group (group HR), hypoxia postconditioning group (group HPO) and hypoxia postconditioning plus an ROS scavenger N-(2-Amidinopropionyl)-glycine (MPG) group (group HPO+ MPG). Cells were exposed to hypoxia for 45 min followed by 60 min reoxygenation to develop the cardiomyocyte hypoxia-reoxygenation injury model.In HPO group, cells were subjected to 3 cycles of 5-min hypoxia/5-min reoxygenation after 45 min hypoxia, followed by reoxygenation for 60 min.In HPO+ MPG group, MPG (final concentration 2 mmol/L) was added at 35 min of hypoxia, cells were subjected to hypoxia for 10 min, and the other treatments were similar to those previously described in group HPO.At the end of reoxygenation, the intracellular calcium level and Nrf2 activity were measured, the ultrastructure of cardiomyocytes was observed, and the Flameng score of mitochondria was assessed, and the expression of Nrf2, NAD(P)H quinine oxidoreductase 1 (NQO1), superoxide dismutase 1 (SOD1) and heme oxygenase-1 (HO-1) protein and mRNA was detected using real-time polymerase chain reaction and Western blot. Results:Compared with group N, the intracellular free Ca 2+ level, Nrf2 activity and Flameng score were significantly increased, and the expression of Nrf2, NQO1, SOD1 and HO-1 protein and mRNA was down-regulated in group HR ( P<0.05). Compared with group HR, the intracellular free Ca 2+ level and Flameng score were significantly decreased, the Nrf2 activity was increased, and the expression of Nrf2, NQO1, SOD1 and HO-1 protein and mRNA was up-regulated in group HPO ( P<0.05). Compared with group HPO, the intracellular free Ca 2+ level and Flameng score were significantly increased, the Nrf2 activity was decreased, and the expression of Nrf2, NQO1, SOD1 and HO-1 protein and mRNA was down-regulated in group HPO+ MPG ( P<0.05). Conclusions:The mechanism by which hypoxia postconditioning activates the Nrf2/ARE signaling pathway in rat cardiomyocytes may be related to ROS.

Role of GLP-1R signaling pathway in sevoflurane postconditioning-induced attenuation of myocardial ischemia-reperfusion injury in rats / 中华麻醉学杂志

Objective:To evaluate the role of glucagon-like peptide-1 receptor (GLP-1R) signaling pathway in sevoflurane postconditioning-induced attenuation of myocardial ischemia-reperfusion (I/R) injury in rats.Methods:Eighty SPF healthy adult male Sprague-Dawley rats, aged 8-10 weeks, weighing 300-340 g, were divided into 4 groups ( n=20 each) by a random number table method: sham operation group (group S), myocardial I/R group (group I/R), myocardial I/R plus sevoflurane postconditioning group (group ISP), and myocardial I/R plus sevoflurane postconditioning plus GLP-1R antagonist group (group ISPE). The myocardial I/R injury model was developed by ligating the left anterior descending branch of the coronary artery for 40 min followed by 2-h reperfusion in anesthetized rats.In group ISP, the rats inhaled 2.4% sevoflurane for 15 min starting from the beginning of reperfusion.In group ISPE, GLP-1R antagonist Exendin9-39 50 μg/kg (in 1 ml 0.9% normal saline) was intraperitoneally injected once a day from 28 days before development of the model, the last intraperitoneal injection was completed at 40 min before inhalation of sevoflurane, and the other treatments were the same as those previously described in group ISP.Blood samples from the abdominal aorta were collected immediately after reperfusion to determine the serum levels of creatine kinase-MB (CK-MB) and lactate dehydrogenase (LDH). Then the rats were sacrificed, and the hearts were obtained for microscopic examination of the histopathological changes of myocardial tissues (by HE staining) and the ultrastructure of cardiomyocytes (with a transmission electron microscope) for determination of the myocardial infarct size (TTC staining), expression of GLP-1R in myocardium (by immunohistochemical staining), expression of GLP-1R, cyclic adenosine monophosphate (cAMP), protein kinase A (PKA), cAMP response element-binding protein (CREB), phospho-CREB (p-CREB), B-cell lymphoma-2 (Bcl-2) and Bcl-2 associated x protein (Bax) in myocardium (by Western blot). The ratios of p-CREB/CREB and Bcl-2/Bax were calculated. Results:Compared with group S, the serum levels of CK-MB and LDH and percentage of myocardial infarct size were significantly increased, the expression of GLP-1R was up-regulated, the expression of cAMP and PKA was down-regulated, and the p-CREB/CREB ratio and Bcl-2/Bax ratio were decreased in group I/R ( P<0.05). Compared with group I/R, the serum levels of CK-MB and LDH and percentage of myocardial infarct size were significantly decreased, the expression of GLP-1R, cAMP and PKA was up-regulated, and p-CREB/CREB ratio and Bcl-2/Bax ratio were increased in group ISP ( P<0.05). Compared with group ISP, the serum levels of CK-MB and LDH and percentage of myocardial infarct size were significantly increased, the expression of GLP-1R, cAMP and PKA was down-regulated, and the p-CREB/CREB ratio and Bcl-2/Bax ratio were decreased in group ISPE ( P<0.05). Conclusions:Sevoflurane postconditioning can attenuate myocardial I/R injury by activation of GLP-1R signal pathway and inhibition of cardiomyocyte apoptosis in rats.

Ceiling effect of Postconditioning and Atrial Natriuretic Peptide in Cardioprotection against Ischemia Reperfusion Injury in Ovariectomized rat hearts

Abstract Ischemic postconditioning (IPTC) brings cardioprotection endogenously, Atrial natriuretic peptide (ANP) produces the same effect. It happens due to down expression of endothelial nitric oxide synthase (eNOS). Thus, experimental protocol associating IPTC has been formulated to find the role of ANP in the cardioprotection of heart in OVX rats. For this experiment, heart was isolated from OVX rat and held tightly on Langendorff's apparatus in a manner that ischemia of 30 min and reperfusion of 120 min were also given. Simultaneously, IPTC with four cycles of 5 min ischemia and 5 min reperfusion of each was applied. Parameters like size of myocardial infarct, levels of lactate dehydrogenase (LDH) and release of creatine kinase- MB (CK-MB) in coronary effluent were noted after each stage of experiment for ensuring the extent of myocardial injury. Some significant changes were also seen in the histopathology of cardiovascular tissues. The cardio-protection has been made by four cycles of IPTC. It was confirmed by decline in the size of myocardial infarct. It diminishes the release of LDH and CK-MB in heart of OVX rat. Thus, IPTC induces cardio-protection in the isolated heart from OVX rat. Perfusion of ANP associating with IPTC favors the cardioprotection which is further confirmed by rise in the NO release and heart rate. The level of myocardial damage changes using IPTC, IPTC+OVX, IPTC+OVX+ANP, IPTC+ OVX+ANP+L-NAME and other groups were observed significantly and were found to be less than those in I/R control group. Thus, it is recommended that ANP involving IPTC restores attenuated cardio-protection in OVX rat heart. Therefore, Post-conditioning is useful in various clinical aspects.

Protective effects of ischemic postconditioning on skeletal muscle following crush syndrome in the rat

ABSTRACT Purpose To investigate the effect of ischemic postconditioning (IPostC) on skeletal muscle and its optimal protocol. Methods This article is about an animal study of rat model of crush syndrome. Sixty rats were randomized into nine different IPostC intervention groups and a control group. The anesthetized rats were subjected to unilateral hindlimb 3-kg compression with a compression device for 6 h, followed by nine different IPostC intervention protocols. Results Serum levels of creatine kinase (CK) at 3 h post-crush became 2.3-3.9 times among all 10 groups after crush. At 72 h post-crush, serum CK level was reduced to 0.28-0.53 time in all intervention groups. The creatinine (CREA) level in the control group was elevated to 3.11 times at 3 h post-crush and reduced to1.77 time at 72 h post-crush. The potassium (K+) level in the control group was elevated to 1.65 and 1.41 time at 3 and 72 h post-crush, respectively. Conclusions Our IPostC intervention protocols can effectively protect rats from crush-induced elevation of serum CK, CREA, and K+ levels. The timing of IPostC intervention should be as early as possible, to ensure the protective effect.

Remote ischemic conditioning improves rat brain antioxidant defense in a time-dependent mechanism

ABSTRACT Purpose To clarify the best protocol for performing remote ischemic conditioning and to minimize the consequences of ischemia and reperfusion syndrome in brain, the present study aimed to evaluate different time protocols and the relation of the organs and the antioxidant effects of this technique. Methods The rat's left femoral artery was clamped with a microvascular clamp in times that ranged from 1 to 5 minutes, according to the corresponding group. After the cycles of remote ischemic conditioning and a reperfusion of 20 minutes, the brain and the left gastrocnemius were collected. The samples were used to measure glutathione peroxidase, glutathione reductase and catalase levels. Results In the gastrocnemius, the 4-minute protocol increased the catalase concentration compared to the 1-minute protocol, but the latter increased both glutathione peroxidase and glutathione reductase compared to the former. On the other hand, the brain demonstrated higher catalase and glutathione peroxidase in 5-minute group, and the 3-minute group reached higher values of glutathione reductase. Conclusions Remote ischemic conditioning increases brain antioxidant capacity in a time-dependent way, while muscle presents higher protection on 1-minute cycles and tends to decrease its defence with longer cycles of intermittent occlusions of the femoral artery.

Relationship between phosphorylation of GSK-3β and high glucose-caused abolition of cardioprotection induced by sevoflurane postconditioning / 中华麻醉学杂志

Objective:To evaluate the relationship between phosphorylation of glycogen synthase kinase-3β (GSK-3β) and high glucose-caused abolition of cardioprotection induced by sevoflurane postconditioning.Methods:H9c2 cells were incubated in normal glucose (5.56 mmol/L) DMEM culture medium or high glucose (33 mmol/L) DMEM culture medium.The cells were divided into 8 groups ( n=24 each) using a random number table method: normal control group (group NC), normal glucose-cultured hypoxia/reoxygenation (H/R) group (group NH/R), normal glucose-cultured sevoflurane postconditioning group (group NS), normal glucose-cultured GSK-3β inhibitor SB216763 group (group NSB), high glucose-cultured group (group HC), high glucose-cultured H/R group (group HH/R), high glucose-cultured sevoflurane postconditioning group (group HS) and high glucose-cultured GSK-3β inhibitor SB216763 group (group HSB). The model of cardiomyocyte H/R was established by subjecting cardiomyocytes to 3 h of hypoxia followed by reoxygenation.Immediately after onset of reoxygenation, cardiomyocytes were exposed to 2.4% sevoflurane for 30 min in Ns and HS groups.Before the beginning of reoxygenation, GSK-3β inhibitor SB216763 was added to the culture medium with the final concentration of 10 μmol/L in NSB and HSB groups.At 3 h of reoxygenation, the apoptosis rate was determined by Anexin V-PI flow cytometry, the expression of GSK-3β and phosphorylated GSK-3β (p-GSK-3β) was detected by Western blot, superoxide dismutase (SOD) activity was measured using xanthineoxidase method, and lactic dehydrogenase (LDH) activity and malondialdehyde (MDA) content were determined by colorimetric assay. Results:Compared with group NC, apoptosis rate, LDH activity and MDA content were significantly increased, and SOD activity was decreased in group NH/R and group HC, expression of GSK-3β was up-regulated, and expression of p-GSK-3β was down-regulated in group NH/R, expression of p-GSK-3β was up-regulated in group NS, and expression of p-GSK-3β was down-regulated in group HC ( P<0.05). Compared with group NH/R, apoptosis rate, LDH activity and MDA content were significantly decreased, and SOD activity was increased in group NS and NSB groups, and expression of GSK-3β was down-regulated, and expression of p-GSK-3β was up-regulated in group NS ( P<0.05). Compared with group HC, apoptosis rate, LDH activity and MDA content were significantly increased, SOD activity was decreased, expression of GSK-3β was up-regulated, and expression of p-GSK-3β was down-regulated in group HH/R ( P<0.05). Compared with group HH/R, apoptosis rate, LDH activity and MDA content were significantly decreased, and SOD activity was increased in group HSB ( P<0.05). Conclusion:The mechanism by which high glucose abolishes cardioprotection induced by sevoflurane postconditioning is related to inhibiting phosphorylation of GSK-3β.

Mitochondrial mechanism of diabetic mellitus-caused abolition of cardioprotection induced by ischemia postconditioning in rats: succinate dehydrogenase / 中华麻醉学杂志

Objective:To evaluate the relationship between the mitochondrial mechanism of diabetic mellitus-caused abolition of cardioprotection induced by ischemia postconditioning (IPO) and succinate dehydrogenase (SDH) in rats.Methods:Thirty-six SPF male non-diabetic Sprague-Dawley rats, aged 16-20 weeks, weighing about 300 g, were divided into 3 groups ( n=12 each) using a random number table method: sham operation group (ND+ Sham group), ischemia-reperfusion (I/R) group (ND+ I/R group) and IPO group (ND+ IPO group). Seventy-two rats with diabetes mellitus were divided into 6 groups ( n=12 each) using a random number table method: sham operation group (DM+ Sham group), I/R group (DM+ I/R group), DM+ IPO group, sham operation+ dimethyl malonate group (group DM+ Sham+ Dme), I/R+ dimethyl malonate group (group DM+ I/R + Dme) and IPO+ dimethyl malonate group (group DM+ IPO+ Dme). The model of cardiopulmonary bypass (CPB) was established, and the model of total I/R injury was induced by ligating the ascending aorta for 30 min followed by 60 min of reperfusion.The animals underwent 3 cycles of 30-s reperfusion followed by 30-s ischemia starting from the onset of reperfusion in each IPO group.In each Dme group, dimethyl malonate was infused through the tail vein at a rate of 4 mg· kg -1·min -1 for 40 min starting from the beginning of CPB.At the end of reperfusion, the myocardial tissues were taken for measurement of mitochondrial respiratory control ratio (RCR) (by the Lufthansa electrode method), mitochondrial membrane potential (MMP) (by the JC-1 method) and the opening of mitochondrial permeability transition pore (mPTP) (by absorptiometry) and for determination of the activity of reactive oxygen species (ROS) (with the fluorescent probe), succinate dehydrogenase (SDH) (using spectrophotometric method) and the contents of succinic acid and fumarate. Results:Compared with ND+ Sham group, the activities of SDH and ROS, opening of mPTP and content of fumarate were significantly increased, and MMP, RCR and succinic acid content were decreased in ND+ I/R ( P<0.05). Compared with group ND+ I/R, the activities of SDH and ROS, opening of mPTP and content of fumarate were significantly decreased, and MMP, RCR and succinic acid content were increased in ND+ IPO ( P<0.05). Compared with group DM+ Sham, the activities of SDH and ROS, opening of mPTP and content of fumarate were significantly increased, and MMP, RCR and succinic acid content were decreased in group DM+ I/R ( P<0.05). Compared with group DM+ I/R, no significant change was found in the parameters mentioned above in group DM+ IPO ( P>0.05). Compared with group DM+ IPO, the activities of SDH and ROS, opening of mPTP and content of fumarate were significantly decreased, and MMP, RCR and succinic acid content were increased in group DM+ IPO+ Dme ( P<0.05). Compared with group DM+ I/R+ Dme, the activities of SDH and ROS, opening of mPTP and content of fumarate were significantly decreased, and MMP, RCR and succinic acid content were increased in group DM+ IPO+ Dme ( P<0.05). Conclusion:The mitochondrial mechanism of diabetic mellitus-caused abolition of cardioprotection induced by IPO may be related to the enhancement of SDH activity in rats.

Effect of propofol postconditoning on Rb-E2F1 signaling pathway in hippocampal neurons in a rat model of oxygen-glucose deprivation and restoration / 中华麻醉学杂志

Objective:To evaluate the effect of propofol postconditoning on retinoblastoma protein (Rb)-E2F1 signaling pathway in hippocampal neurons in a rat model of oxygen-glucose deprivation and restoration (OGD/R).Methods:Pregnant Wistar rats at 16-18 days of gestation were sacrificed, and the hippocampal neurons of fetal rats were obtained and primarily cultured for 7 days.The neurons were divided into 3 groups ( n=42 each) using a random number table method: control group (group C), OGD/R group (group O) and propofol postconditoning group (group P). In group O, the neurons were subjected to oxygen-glucose deprivation for 1 h, followed by restoration of oxygen-glucose.In group P, propofol (final concentration 1.2 μg/ml) was added immediately after restoration of oxygen and glucose, and the cells were cultured for 2 h and then the culture medium was replaced with plain culture medium.At 24 h of culture, the expression of p-Rb and E2F1 was determined by Western blot, and the cell cycle and apoposis rate were assessed by flow cytometry. Results:Compared with group C, the apoptosis rate was significantly increased, expression of p-Rb and E2F1 was up-regulated, the ratio of p-Rb nuclear/plasmosin protein and the proportion of neurons in G 0/G 1 phase were decreased, and the proportion of neurons in S and G 2/M phases was increased in O and P groups ( P<0.05). Compared with group O, the apoptosis rate was significantly decreased, expression of p-Rb and E2F1 was down-regulated, the ratio of p-Rb nuclear/plasmosin protein and the proportion of neurons in G 0/G 1 phase were increased, and the proportion of neurons in S and G 2/M phases was decreased in group P ( P<0.05). Conclusion:The mechanism by which propofol postconditioning decreases the apoptosis in hippocampal neurons is related to inhibiting Rb-E2F1 signaling pathway in a rat model of OGD/R.

Neuroprotective mechanism of autophagy in bradykinin postconditioning after cardiac arrest in rats / 中华危重病急救医学

Objective:To explore the protective effects of bradykinin postconditioning on cardiopulmonary resuscitation (CPR) rats, and to assess the underlying mechanisms.Methods:Forty-eight adult male Sprague-Dawley (SD) rats were randomly divided into four groups according to random number table: Sham operation group, cardiac arrest (CA) group, bradykinin treatment (BK) group, and AMP-activated protein kinase (AMPK) inhibitor Compound C+ bradykinin treatment (CP+BK) group, finally, 8 rats in each group were taken for follow-up experiment. CA was induced by asphyxia. Rats in the Sham group received arteriovenous catheterization, endotracheal intubation, and mechanical ventilation, without CA. Compound C (250 μg/kg) was intraperitoneally injected in CP+BK group 30 minutes before CA, and the same volume of dimethyl sulfoxide (DMSO) was given in the remaining groups. Bradykinin (150 μg/kg) was intraperitoneally injected in BK group and CP+BK group 48 hours after restoration of spontaneous circulation (ROSC), and same volume of saline was given in the remaining groups. The neural function of rats in each group was evaluated with neurological deficit score (NDS) 72 hours after ROSC. Microtubule-associated protein light chain 3 (LC3) and p62 expressions were detected by immunohistochemistry, autophagosomes were observed by transmission electron microscopy, and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling method (TUNEL) assay was used to assess apoptosis.Results:Compared with the Sham group, the NDS was decreased (60.75±5.80 vs. 80.00±0.00, P < 0.01), the expression levels of LC3 and p62 elevated [LC3 ( A value): 1.04±0.64 vs. 0.40±0.14, p62 ( A value): 2.75±0.57 vs. 0.36±0.12, both P < 0.05], the number of autophagosomes and apoptotic cells increased in the CA group [(39.00±8.00)% vs. (3.87±1.90)%, P < 0.05]. Compared with the CA group, the NDS (67.75±6.32 vs. 60.75±5.80, P < 0.05), the expression of LC3 ( A value: 1.60±0.34 vs. 1.04±0.64, P < 0.05), and the number of autophagosomes increased in the BK group, while the expression of p62 and the rate of apoptotic cells reduced [p62 ( A value): 1.51±0.32 vs. 2.75±0.57, apoptotic cells rate: (23.03±1.91)% vs. (39.00±8.00)%, both P < 0.05]. Compared with the BK group, the NDS (59.00±8.19 vs. 67.75±6.32, P < 0.05), the expression of LC3 ( A value: 0.62±0.41 vs. 1.60±0.34, P < 0.05) and the number of autophagosomes declined in the CP+BK group, while the expression of p62 and the rate of apoptotic cells elevated [p62 ( A value): 3.50±0.47 vs. 1.51±0.32, apoptotic cells rate: (44.53±10.15)% vs. (23.03±1.91)%, both P < 0.05]. Conclusion:Bradykinin postconditioning played a neuroprotective role in CPR rats by activating autophagy and reducing apoptosis.

Protective effects of hypoxia inducible factor-1α on myocardial ischemia postconditioning in rats / 中国小儿急救医学

Objective:To investigate the protective role and mechanism of hypoxia inducible factor(HIF)-1α in myocardial ischemia postconditioning.Methods:Forty healthy adult SD rats were randomly divided into four groups with 10 rats in each group.The control group(group A)was sham operation group, and the rats underwent the same surgical procedures except that the suture passed under the left anterior descending branch(LAD)of the coronary artery was not tightened for 225 minutes.In the ischemia-reperfusion group(group B), the LAD was blocked for 45 minutes, and then reperfusion for 3 hours.In the ischemic postconditioning group(group C), 45 minutes after blocking the LAD, reperfusion was performed for 10 seconds-ischemia for 10 seconds at the beginning of reperfusion, a total of 3 cycles of intervention, and reperfusion for 3 hours.Ischemic postconditioning + HIF-1α inhibitor group(group D): 45 minutes after blocking the LAD, HIF-1α inhibitor AG490 (3 μg/g) was injected intraperitoneally, and reperfusion was performed for 10 seconds-ischemia 10 seconds at the moment of reperfusion.A total of 3 cycles of intervention, reperfusion for 3 hours.Blood samples were harvested from femoral vein at three time points(before ligation of the LAD, 45 minutes after ischemia, 3 hours after reperfusion)to analyze the serum levels of creatine kinase and cardiac troponin respectively.After 3 hours of reperfusion, myocardial tissue was used to measure the infarction size through 2, 3, 5-triphenyltetrazolium chloride staining method; and Western blot method was used to detect the expression of HIF-1α in each group.Results:(1) There were no significant differences in the serum levels of creatine kinase and cardiac troponin among four groups before ligation( P>0.05); 45 minutes after ischemia, there were significant differences between group B, group C, and group D compared with group A ( P<0.01). After 3 hours of reperfusion, there were significant differences between group B, group C, and group D compared with group A (all P<0.01), and group B, group D were significantly higher than that in group C ( P<0.05). (2)Compared with group A[(2.46±1.13)%], the area of myocardial infarction in group B was (45.81±5.96)%, in group C was (37.17±4.99)%, and group D was (45.00±3.29) %, and the differences were statistically significant ( P<0.01). (3)The HIF-1α protein in myocardial tissue in group A was slightly expressed; the expression of HIF-1α protein in group B was higher than that in group A( P<0.05); and group C was significantly higher than that in group B ( P<0.05); HIF-1α protein was almost not expressed in group D. Conclusion:After ischemic postconditioning, HIF-1α increased in myocardium; the increased expression of HIF-1α may be involved in the protective process of myocardial ischemic postconditioning in rats.

Protective mechanism of sevoflurane inhalation anesthesia on neurological function in rats with cerebral infarction / 国际生物医学工程杂志

Objective:To investigate the protective mechanism of sevoflurane inhalation anesthesia on neurological function in rats with cerebral infarction.Methods:Sixty SD rats were randomly and equally divided into the sham group, cerebral obstruction group, and sevoflurane post conditioning group (Sevo group). Rats in the cerebral obstruction group and Sevo group were underwent wire embolization to establish permanent focal cerebral ischemia rat model. Rats in the sham group were not treated with wire embolization. Rats in the Sevo group received sevoflurane at a volume fraction of 2.5% immediately after reperfusion and were maintained with oxygen for 30 min with 1 L/min oxygen flow. Rats in the sham and cerebral obstruction group received 30 min of continuous oxygen inhalation with 1 L/min oxygen flow. After 24 h, modified neurological deficit bisection (mNSS) was used to assess the neurological function of the rats in the three groups. After that, blood was taken and the rats were sacrificed, and their brain tissues were collected to determine the level of cerebral infarction volume, apoptosis rate, and the levels of serum inflammatory factors, including interleukin (IL)-6, IL-10, IL-1β and tumor necrosis factor-α (TNF-α), as well as malondialdehyde (MDA) levels, superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities in brain tissue. Toll like receptor 4 (TLR4) and nuclear transcription factor κB (NF-κB) p65 protein expression levels in rat brain tissues were determined by Western blot analysis.Results:In the Sevo group, the mNSS score, cerebral infarct volume ratio, apoptosis rate, IL-6 level, IL-1β level, TNF-α level, MDA level as well as the expression levels of TLR4 and NF-κB p65 in the brain tissues were higher than those of the sham group (all P<0.05) and lower than those of the cerebral obstruction group (all P<0.05). In the Sevo group, IL-10 level as well as SOD and GSH-Px activities were lower than those of the sham group (all P<0.05) and higher than those of the cerebral obstruction group (all P<0.05). Conclusions:Sevoflurane has a certain protective effect on the brain tissue and neurological function of rats with cerebral infarction. This protective effect may be achieved by inhibiting the inflammatory response mediated by the TLR4/NF-κB signal channel, reducing the release of inflammatory factors, reducing inflammation and oxidative stress, and inhibiting cell apoptosis.

Application of remote ischemic conditioning in patients with acute ischemic stroke / 国际脑血管病杂志

Recanalization therapy is the standard treatment for acute ischemic stroke. However, sometimes blood flow reperfusion not only fails to restore brain function, but also leads to further necrosis and apoptosis of neurons, thereby aggravating brain tissue damage and brain dysfunction of the patients, that is, reperfusion injury. Remote ischemic conditioning (RIC) is a simple, safe, convenient and easy method to protect brain tissue, improve cerebral blood flow and alleviate ischemia-reperfusion injury by giving multiple transient ischemic treatments to remote organs (usually limbs). This article reviews the application of RIC in the field of acute ischemic stroke in recent years.

Comparison of remote and local postconditioning against hepatic ischemic-reperfusion injury in rats

ABSTRACT Purpose: The aim of this study is to compare the hepatic protective effect of both remote and local postconditioning (POS). Methods: Twenty-eight Wistar rats were assigned into four groups: sham group(SHAM), ischemia-reperfusion group (IR), local ischemic POS group (lPOS) and remote ischemic POS group (rPOS). Animals were subjected to liver ischemia for 30 min. Local ischemic POS group consisted of four cycles of 5 min liver ischemia, followed by 5 min reperfusion (40 min). Remote ischemic POS group consisted of four cycles of 5 min hind limb ischemia, followed by 5 min hind limb perfusion after the main liver ischemia period. After 190 minutes median and left liver lobes were harvested for biochemical and histopathology analysis. Results: All the conditioning techniques were able to increase the level of bothglutathione reductase and peroxidase, showing higher values in the rPOS group when compared to the lPOS. Also, thiobarbituric acid reactive substances were higher in all intervention groups when compared to SHAM, but rPOS had the lower rates of increase, showing the best result. The histopathology analysis showed that all groups had worst injury levels than SHAM, but rPOS had lower degrees of damage when compared to the lPOS, although it was not statistically significant. Conclusion: Remote postconditioning is a promising technique to reduce liver ischemia-reperfusion injury, once it increased antioxidants substances and reduced the damage.

Advance in Role of Mitochondria in Remote Ischemic Postconditioning for Cerebral Ischemia-reperfusion Injury (review) / 中国康复理论与实践

Mitochondria, as the key passway of neuronal apoptosis after ischemia, is closely related to cerebral ischemia-reperfusion injury. Remote ischemic post-conditioning can alleviate cerebral ischemia-reperfusion injury, and its mechanism is related to alleviating mitochondrial injury and improving its dysfunction. In this paper, cytochrome C/caspase, mitophagy, mitochondrial ATP-sensitive K+ channel and mitochondrial permeability transitionpore were reviewed.