Sevoflurane Postconditioning Group Research Articles

Sevoflurane postconditioning attenuates cardiomyocytes hypoxia/reoxygenation injury via PI3K/AKT pathway mediated HIF-1α to regulate the mitochondrial dynamic balance

BackgroundMyocardial ischemia-reperfusion injury (I/RI) is a major cause of perioperative cardiac-related adverse events and death. Studies have shown that sevoflurane postconditioning (SpostC), which attenuates I/R injury and exerts cardioprotective effects, regulates mitochondrial dynamic balance via HIF-1α, but the exact mechanism is unknown. This study investigates whether the PI3K/AKT pathway in SpostC regulates mitochondrial dynamic balance by mediating HIF-1α, thereby exerting myocardial protective effects.MethodsThe H9C2 cardiomyocytes were cultured to establish the hypoxia-reoxygenation (H/R) model and randomly divided into 4 groups: Control group, H/R group, sevoflurane postconditioning (H/R + SpostC) group and PI3K/AKT blocker (H/R + SpostC + LY) group. Cell survival rate was determined by CCK-8; Apoptosis rate was determined by flow cytometry; mitochondrial membrane potential was evaluated by Mito Tracker™ Red; mRNA expression levels of AKT, HIF-1α, Opa1and Drp1 were detected by quantitative real-time polymerase chain reaction (qRT-PCR); Western Blot assay was used to detect the protein expression levels of AKT, phosphorylated AKT (p-AKT), HIF-1α, Opa1 and Drp1.ResultsCompared with the H/R group, the survival rate of cardiomyocytes in the H/R + SpostC group increased, the apoptosis rate decreased and the mitochondrial membrane potential increased. qRT-PCR showed that the mRNA expression of HIF-1α and Opa1 were higher in the H/R + SpostC group compared with the H/R group, whereas the transcription level of Drp1 was lower in the H/R + SpostC group. In the H/R + SpostC + LY group, the mRNA expression of HIF-1α was lower than the H/R + SpostC group. There was no difference in the expression of Opa1 mRNA between the H/R group and the H/R + SpostC + LY group. WB assay results showed that compared with the H/R group, the protein expression levels of HIF-1α, Opa1, P-AKT were increased and Drp1 protein expression levels were decreased in the H/R + SpostC group. HIF-1α, P-AKT protein expression levels were decreased in the H/R + SpostC + LY group compared to the H/R + SpostC group.ConclusionSpostC mediates HIF-1α-regulated mitochondrial fission and fusion-related protein expression to maintain mitochondrial dynamic balance by activating the PI3K/AKT pathway and increasing AKT phosphorylation, thereby attenuating myocardial I/R injury.

Effects of sevoflurane post-conditioning in cerebral ischemia-reperfusion injury via TLR4/NF-κB pathway in rats.

The aim of the study was to investigate the anti-inflammatory effect of sevoflurane post-conditioning on cerebral ischemia-reperfusion injury in rats. Thirty Sprague Dawley (SD) rats were randomly divided into 3 groups: sham operation group (Sham), ischemia/reperfusion injury (I/R) group and sevoflurane post-conditioning group (Se). Hematoxylin-eosin (HE) staining was used to observe the inflammatory response in the brain tissue. The levels of TNF-α, IL-1β, IL-6 in serum were measured by ELISA. The mRNA and protein expression of TLR4 and NF-κB p65 were detected by RT-PCR and Western blot in the brain tissue. The post-conditioning of sevoflurane decreased the level of inflammatory reaction in ischemic-reperfusion rat cerebral infarction area and reduced the levels of pro-inflammatory cytokines such as TNF-α, IL-1β, IL-6 in rats with ischemia-reperfusion injury. In addition, after treatment with sevoflurane, the mRNA and protein expression of TLR4 and NF-κBp65 in TLR4/NF-κB pathway was inhibited. Sevoflurane post-conditioning can decrease the inflammatory reaction in cerebral infarct area induced by cerebral ischemia-reperfusion injury in rats. The neuroprotective effect mechanism of sevoflurane may be related to TLR4/NF-κB signaling pathway.

Relationship between failed mechanism of sevoflurane postconditioning-induced myocardial protection and dynamin-related protein 1 activity in diabetic rats

Objective To evaluate the relationship between the failed mechanism of sevoflurane postconditioning-induced myocardial protection and the activity of dynamin-related protein 1(Drp1)in diabetic rats. Methods Pathogen-free healthy adult male Sprague-Dawley rats, weighing 220-280 g, in which diabetes mellitus was induced by combination of high-fat and high-sucrose diet and intraperitoneal injection of streptozotoein 30 mg/kg, were studied.Sixty rats with diabetes mellitus were divided into 5 groups(n=12 each)using a random number table: sham operation group(group Sham), myocardial ischemia/reperfusion(I/R)group(group I/R), sevoflurane postconditioning group(group SP), Drp1 inhibitor mitochondrial division inhibitor-1(Mdivi-1)group(group M)and Mdivi-1 plus sevoflurane postconditioning group(group M-SP). Myocardial I/R was induced by occluding the left anterior descending branch of the coronary artery for 30 min followed by 120 min reperfusion except for group Sham.Mdivi-1 1.2 mg/kg was intraperitoneally injected at 15 min before ischemia in M and M-SP groups, and 2.5% sevoflurane was inhaled starting from 5 min of reperfusion in SP and M-SP groups.Blood samples were collected from the right internal jugular vein at 120 min of reperfusion for measurement of serum cardiac troponin I(cTnI)concentrations(by enzyme-linked immunosorbent assay). Rats were then sacrificed and myocardial specimens were obtained for determination of the myocardial infarct size(by TTC), cell apoptosis(by TUNEL), expression of Bax, Bcl-2 and activated caspase-3(by Western blot)and nicotinamide adenine dinucleotide(NAD+ )content(by spectrophotometry). Apoptosis index(AI)and Bax/Bcl-2 ratio were calculated. Results Compared with group Sham, the percentage of myocardial infarct size, serum concentration of cTnI, AI and Bax/Bcl-2 ratio were significantly increased, the expression of activated caspase-3 was up-regulated, and the NAD+ content was decreased in the other four groups(P 0.05). Compared with group SP, the percentage of myocardial infarct size, serum concentration of cTnI, AI and Bax/Bcl-2 ratio were significantly decreased, the expression of activated caspase-3 was down-regulated, and the NAD+ content was decreased in group M-SP(P 0.05). Conclusion The failed mechanism of sevoflurane postconditioning-induced myocardial protection may be related to the activity of Drp1 in diabetic rats. Key words: Diabetes mellitus; Myocardial reperfusion injury; Anesthetics, inhalation; Apoptosis

Effect of sevoflurane postconditioning on microtubule structure during myocardial ischemia-reperfusion in mice

Objective To evaluate the effect of sevoflurane postconditioning on microtubule structure during myocardial ischemia-reperfusion (I/R) in mice. Methods Thirty-two healthy male C57 mice, aged 7-8 weeks, wighing 20-30 g, were divided into 4 groups (n=8 each) using a random number table: sham operation group (Sham group), group I/R, sevoflurane postconditioning group (group SP), and microtubule depolymerizer colchicine plus sevoflurane postconditioning group (group CSP). Myocardial I/R was produced by occlusion of the left anterior descending branch of coronary artery for 30 min followed by 120 min reperfusion in I/R, SP and CSP groups.Colchicine 0.04 μmol/kg was intraperitoneally injected at 30 min before ischemia in group CSP.In SP and CSP groups, 2.4% sevoflurane was inhaled for 15 min starting from onset of reperfusion.Mice were sacrificed at 120 min of reperfusion, and myocardial specimens were obtained for determination of myocardial infarct size and expression of α-tubulin (by Western blot). Results Compared with group Sham, the myocardial infarct size was significantly increased, and the expression of α-tubulin was down-regulated in the other three groups (P 0.05). Compared with group SP, the myocardial infarct size was significantly increased, and the expression of α-tubulin was down-regulated in group CSP (P<0.05). Conclusion The mechanism by which sevoflurane postconditionning reduces myocardial I/R injury is related to stabilizing microtubule structure of mice. Key words: Anesthetics, inhalation; Ischemic postconditionning; Myocardial reperfusion injury; Microtubules

Anesthetic postconditioning plus hypothermia following cardiopulmonary resuscitation protects the myocardial ultrastructure by modulating inflammatory events in rabbits

Myocardial ischemia/reperfusion (I/R) injury is usually caused by resuscitation following cardiac arrest. The aim of the present study was to investigate the influence of sevoflurane postconditioning on the myocardial ultrastructure induced by cardiac arrest and successful resuscitation in mature rabbits. A total of 32 rabbits were randomly and equally divided into an I/R group (I/R group), a hypothermia group (H group), a sevoflurane postconditioning group (S group), and hypothermia plus sevoflurane postconditioning group (H + S group). Interleukin (IL)-8 and IL-10 levels in blood were evaluated at four different time points (1 h pre-ischemia: T1; 1, 2 and 3 h after reperfusion: T2, T3 and T4, respectively). The myocardial ultrastructure was evaluated by microscope after the rabbits were scarified. Plasma levels of IL-8 and IL-10 increased in all of the groups from T2. However, compared with the I/R group from T3 and T4, downregulation of IL-8 was significant in the S and H + S groups (P<0.05), and the result of intra-group comparison demonstrated that the level of serum IL-8 was the lowest in the H + S group (P<0.05). By contrast, upregulation of IL-10 was significantly higher in the S and H + S groups (P<0.05), particularly in the H + S group. Notably, ultrastructure damage of the myocardium was significantly lighter, and the structural integrity of the myocardium in the H + S group was better when compared with that of the S group. Thus, sevoflurane postconditioning plus hypothermia protected the myocardial ultrastructure following cardiopulmonary resuscitation by suppressing inflammatory effects.

Role of peroxisome proliferator-activated receptor-γ in sevoflurane postconditioning reduce myocardial ischemia-reperfusion injury in mice

Objective To observe the effect of sevoflurane on peroxisome proliferator-activated receptor-γ (PPAR-γ) in reperfusion myocardium and study the role of PPAR-γ in sevoflurane postconditioning against myocardial ischemia-reperfusion injury. Methods Male C57BL/6 mice were randomly allocated into four groups (n=5 each): Control group, Sevoflurane postconditioning (SPostC) group, Sevoflurane postconditioning+ PPAR-γ inhibitor (SPostC+ GW9662) group, PPAR-γ inhibitor (GW9662) group. All the groups establish the model of mice myocardial ischemia-reperfusion injury (30 min of ischemia and 120 min of reperfusion) in vivo, mice with myocardial ischemia received 3.4% sevoflurane for 15 min at the onset of reperfusion as the sevoflurane postconditioning, and all the groups inject inhibitor or placebo intraperitoneally at 30 min before ischemia. The heart rate (HR) and mean arterial pressure (MAP) of mice were measured before ischmia and after reperfusion. After experimental time out, heart of mice was excised, myocardial infarct size and PPAR-γ transcriptional activity were tested. Results Compared with Control group [(24.68±1.03)%; 0.081 8±0.006 0], myocardial infarct size [(18.70±2.58)%] reduced (P=0.000) significantly and PPAR-γ transcriptional activity (0.091 8±0.006 8) increased (P=0.026) in SPostC group, myocardial infarct size [(23.55±1.60)%; (23.14±1.46)%] and PPAR-γ transcriptional activity (0.082 4±0.005 7; 0.080 2±0.007 2) had a little change in SPostC+ GW9662 group (P=0.324, P=0.887) and GW9662 group (P=0.185, P=0.690) compared to Control group. HR and MAP before ischemiahave no difference between the groups (P=0.763, P=0.455), after reperfusion, the HR and MAP also have no difference between each groups (P=0.801, P=0.341). Conclusion Sevoflurane postconditioning can reduce myocardial infarct size via activating PPAR-γ and improving its transcriptional activity during myocardial ischemia-reperfusion injury. Key words: Peroxisome proliferator-activated receptor-γ; Sevoflurane postconditioning; Ischemia-reperfusion injury; Myocardial protection

Effect of sevoflurane on activation of NF-κB during brain injury induced by hemorrhagic shock in pigs

Objective To evaluate the effect of sevoflurane on activation of nuclear factor kappa B(NF-κB)during brain injury induced by hemorrhagic shock(HS)in pigs. Methods Thirty-two adult male Bama miniature pigs, aged 6 months, weighing 22-25 kg, were divided into 4 groups(n=8 each)using a random number table: sham operation group(group Sham), HS group, sevoflurane preconditioning group(group Sev-Pre)and sevoflurane postconditioning group(group Sev-Post). The animals were anesthetized, and tracheostomized and mechanically ventilated.In group Sham, the bilateral femoral arteries and internal jugular veins were only cannulated.HS was induced by removing 40% of blood volume within 15 min(30 ml/kg)via the right femoral artery and maintaining at this level for 1 h before resuscitation in HS, Sev-Pre and Sev-Post groups.In group Sev-Pre, 2% sevoflurane was inhaled for 30 min, and then HS was induced.In group Sev-Post, 2% sevoflurane was inhaled for 30 min starting from the time point immediately after HS was induced.Immediately before establishment of the model and at 30, 60, 90, 120, 180 and 240 min of HS(T1-6), blood samples from the jugular vein were collected for determination of serum interleukin-1beta(IL-1β)and tumor necrosis factor-alpha(TNF-α)concentrations by enzyme-linked immunosorbent assay.At 4 h of HS, the rats were sacrificed, and brains were removed for microscopic examination of hippocampal CA1 region(using haematoxylin and eosin staining)and for determination of the expression of NF-κB in nucleoprotein(by Western blot). Results Compared with group Sham, the concentrations of serum IL-1β and TNF-α were significantly increased at T2-6, and the expression of NF-κB in nucleoprotein in hippocampal CA1 region was up-regulated in HS, Sev-Pre and Sev-Post groups(P 0.05). The pathologic changes were significantly attenuated in Sev-Pre and Sev-Post groups as compared with group HS. Conclusion The mechanism by which sevoflurane attenuates brain injury induced by HS may be related to inhibition of NF-κB activation and reduction of inflammatory responses in pigs. Key words: Anesthetics, inhalation; NF-kappa B; Shock, hemorrhagic; Brain injuries

Pim-1 Kinase Regulating Dynamics Related Protein 1 Mediates Sevoflurane Postconditioning-induced Cardioprotection.

Background:It is well documented that sevoflurane postconditioning (SP) has a significant myocardial protection effect. However, the mechanisms underlying SP are still unclear. In the present study, we investigated the hypothesis that the Pim-1 kinase played a key role in SP-induced cardioprotection by regulating dynamics-related protein 1 (Drp1).Methods:A Langendorff model was used in this study. Seventy-two rats were randomly assigned into six groups as follows: CON group, ischemia reperfusion (I/R) group, SP group, SP+proto-oncogene serine/threonine-protein kinase 1 (Pim-1) inhibitor II group, SP+dimethylsufoxide group, and Pim-1 inhibitor II group (n = 12, each). Hemodynamic parameters and infarct size were measured to reflect the extent of myocardial I/R injury. The expressions of Pim-1, B-cell leukemia/lymphoma 2 (Bcl-2) and cytochrome C (Cyt C) in cytoplasm and mitochondria, the Drp1 in mitochondria, and the total Drp1 and p-Drp1ser637 were measured by Western blotting. In addition, transmission electron microscope was used to observe mitochondrial morphology. The experiment began in October 2014 and continued until July 2016.Results:SP improved myocardial I/R injury-induced hemodynamic parametric changes, cardiac function, and preserved mitochondrial phenotype and decreased myocardial infarct size (24.49 ± 1.72% in Sev group compared with 41.98 ± 4.37% in I/R group; P < 0.05). However, Pim-1 inhibitor II significantly (P < 0.05) abolished the protective effect of SP. Western blotting analysis demonstrated that, compared with I/R group, the expression of Pim-1 and Bcl-2 in cytoplasm and mitochondria as well as the total p-Drp1ser637 in Sev group (P < 0.05) were upregulated. Meanwhile, SP inhibited Drp1 compartmentalization to the mitochondria followed by a reduction in the release of Cyt C. Pretreatment with Pim-1 inhibitor II significantly (P < 0.05) abolished SP-induced Pim-1/p-Drp1ser637 signaling activation.Conclusions:These findings suggested that SP could attenuate myocardial ischemia-reperfusion injury by increasing the expression of the Pim-1 kinase. Upregulation of Pim-1 might phosphorylate Drp1 and prevent extensive mitochondrial fission through Drp1 cytosolic sequestration.

Effect of sevoflurane postconditioning on expression of Pim-1 kinase during myocardial ischemia-reperfusion in rats: an in vitro experiment

Objective To evaluate the effect of sevoflurane postconditioning on the expression of Pim-1 kinase during myocardial ischemia-reperfusion(I/R)in rats. Methods 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 an oxygenated K-H solution at 37 ℃ in a Langendorff apparatus.Thirty-six isolated rat hearts were assigned into 3 groups(n=12 each)using a random number table: control group(group C), group I/R and sevoflurane postconditioning group(group SP). 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 SP, the hearts were perfused with K-H solution saturated with 3% sevoflurane for 15 min starting from the beginning of reperfusion.Heart rate(HR), left ventricular end-diastolic pressure(LVEDP), left ventricular developed pressure(LVDP)and the maximum rate of increase and decrease of left ventricular pressure(±dp/dtmax) were recorded at the end of equilibration and 30, 60, 90 and 120 min of reperfusion.Myocardial tissues were obtained at T2 for determination of the expression of Pim-1 kinase, Bcl-2 and cytochrome c(Cyt c)in cytoplasm and mitochondria by Western blot.The hearts were selected at T4 for determination of myocardial infarct size(by TTC staining)and for examination of mitochondrial ultrastructure(with transmission electron microscope). Results Compared with group C, HR, LVDP and ±dp/dtmax were significantly decreased, and LVEDP was increased at T1-4, the myocardial infarct size was enlarged, the expression of Pim-1 and Bcl-2 in cytoplasm and mitochondria was down-regulated, the expression of Cyt c in cytoplasm was up-regulated, and the expression of Cyt c in mitochondria was down-regulated in group I/R(P<0.05). Compared with group I/R, HR, LVDP and ±dp/dtmax were significantly increased, and LVEDP was decreased at T1-4, the myocardial infarct size was decreased, the expression of Pim-1 kinase and Bcl-2 in cytoplasm and mitochondria was up-regulated, the expression of Cyt c in cytoplasm was down-regulated, and the expression of Cyt c in mitochondria was up-regulated in group SP(P<0.05). The damage to mitochondria was significantly attenuated in group SP as compared with group I/R, and was aggravated as compared with group C. Conclusion The mechanism by which sevoflurane postconditioning attenuates myocardial I/R may be related to up-regulation of Pim-1 kinase expression in rats. Key words: Proto-oncogene proteins; Anesthetics, inhalation; Ischemic postconditioning; Myocardial reperfusion injury

Sevoflurane Post-conditioning Enhanced Hippocampal Neuron Resistance to Global Cerebral Ischemia Induced by Cardiac Arrest in Rats through PI3K/Akt Survival Pathway.

The purpose of this current study was to evaluate whether improvement of mitochondrial dysfunction was involved in the therapeutic effect of sevoflurane post-conditioning in global cerebral ischemia after cardiac arrest (CA) via the PI3K/Akt pathway. In the first experiment, animals were randomly divided into three groups: a sham group, a CA group, a CA+sevoflurane post-conditioning group (CA+SE). Sevoflurane post-conditioning was achieved by administration of 2.5% sevoflurane for 30 min after resuscitation. Sevoflurane post-conditioning has a significant neuroprotective effect by increasing survival rates and reducing neuronal apoptosis. Additionally, the gene and protein expression of PGC-1α, NRF-1, and TFAM, the master regulators of mitochondrial biogenesis, were up-regulated in the CA+SE group, when compared to the CA group. Similarly, in contrast to the CA group, mitochondria-specific antioxidant enzymes, including heat-shock protein 60 (HSP60), peroxiredoxin 3 (Prx3), and thioredoxin 2 (Trx2) were also increased in the CA+SE group. Finally, administration of sevoflurane ameliorated mitochondrial reactive oxygen species (ROS) formation and maintained mitochondrial integrity. In the second experiment, we investigated the relationship between the PI3K/Akt pathway and mitochondrial biogenesis and mitochondria-specific antioxidant enzymes in sevoflurane-induced neuroprotection. The selective PI3K inhibitor wortmannin not only eliminated the beneficial biochemical processes of sevoflurane by reducing the level of mitochondrial biogenesis-related proteins and aggravating mitochondrial integrity, but also reversed the elevation of mitochondria-specific antioxidant enzymes induced by sevoflurane. Therefore, our data suggested that sevoflurane post-conditioning provides neuroprotection via improving mitochondrial biogenesis and integrity, as well as increasing mitochondria-specific antioxidant enzymes by a mechanism involving the PI3K/Akt pathway.

Sevoflurane Postconditioning Increases the Activities of Antioxidant Enzymes and Improves Spatial Learning and Memory after Cardiac Arrest in Rats

Background: Sevoflurane, as a novel volatile anesthetic with minimal pungency, low solubility, and less toxicity, is widely used in anesthetic practice. The purpose of this study was to investigate the effect of sevoflurane postconditioning on endogenous antioxidant status and spatial learning and memory ability after cardiac arrest (CA) and the potential underlying mechanisms.Methods: A rat model of CA was established by delivering an alternating current between the esophagus and chest wall to induce ventricular fibrillation. Animals were randomly divided into three groups: sham group (no CA), CA group, and CA+sevoflurane postconditioning (CA+SE) group. Sevoflurane postconditioning was achieved by administration of 2.5% sevoflurane for 60 min after resuscitation. The spatial learning and memory ability of rats was measured by the Morris water maze. The antioxidant enzymes activities were assessed at 4 hours, 1 day and 8 days after resuscitation. Moreover, the expressions of hippocampal proteins which could serve as memory enhancement biomarkers including growth-associated protein-43 (GAP-43), postsynaptic density-95 (PSD-95) and the transcription factor c-jun/activator protein-1 (AP-1), were detected at 8 days after resuscitation.Results: We found that CA significantly decreased the ability of spatial learning and memory in contrast to the sham controls. However, sevoflurane postconditioning significantly increased survival rate and antioxidant enzyme activities as well as ameliorated the spatial learning and memory deficits induced by CA. Furthermore, sevoflurane postconditioning regulated hippocampal memory enhancement proteins.Conclusions: Postconditioning with sevoflurane improved learning and memory deficits in a CA model possibly due to the reduction of oxidative stress and up-regulation of the memory enhancement biomarkers in hippocampus. Citation: Zhi Ye, Zi-Yu Zhou, Na Wang, Ping-Ping Xia, E Wang, Qu-Lian Guo. Sevoflurane postconditioning increases the activities of antioxidant enzymes and improves spatial learning and memory after cardiac arrest in rats. J Anesth Perioper Med 2016; 3: 149-159. doi: 10.24015/JAPM.2016.0020This is an open-access article, published by Evidence Based Communications (EBC). This work is licensed under the Creative Commons Attribution 4.0 International License, which permits unrestricted use, distribution, and reproduction in any medium or format for any lawful purpose. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

Relationship between mitofusin-2 and diabetes mellitus-caused influence on cardioprotection induced by sevoflurane postconditioning in rats

Objective To evaluate the relationship between mitofusin-2 (Mfn-2)expression and diabetes mellitus (DM)-caused influence on cardioprotection induced by sevoflurane postconditioning in rats. Methods Healthy male Sprague-Dawley rats, weighing 210-260 g, were studied.DM was induced by intraperitoneal 1% streptozotocin 60 mg/kg, and confirmed by blood glucose ≥16.7 mmol/L 72 h later.Thirty-six rats with DM were randomly divided into 3 groups (n=12 each) using a random number table: sham operation group (group DMS), myocardial ischemia-reperfusion group (group DMIR), and sevoflurane postconditioning group (group DMSP). Another 36 normal rats were selected, and were also randomly divided into 3 groups (n=12 each) using a random number table: sham operation group (group NS), myocardial ischemia-reperfusion group (group NIR), and sevoflurane postconditioning group (group NSP). Myocardial ischemia was induced by 30 min occlusion of the left anterior descending branch of the coronary artery, followed by 120 min reperfusion.In NSP and DMSP groups, sevoflurane was inhaled for 5 min after the end-tidal concentration reached 2.5% starting from 1 min before reperfusion.The rats were sacrificed at 120 min of reperfusion, and their hearts were removed for measurement of myocardial infarct size (IS) (by TTC), cell apoptosis and Mfn2 expression, and for examination of pathological changes (with light microscope) and ultra-structure (with electron microscope). Apoptosis index (AI) was calculated. Results Compared with group NS, the myocardial IS was significantly enlarged, AI was increased, and the expression of Mfn-2 was down-regulated in NIR and NSP groups (P 0.05). Compared with group NSP, the myocardial IS was significantly enlarged, AI was increased, and the expression of Mfn-2 was down-regulated in group DMSR (P<0.05). The pathological changes were significantly attenuated in group NSP compared with group NIR.No significant difference was found in pathological changes between group DMSP and group DMIR. Conclusion The mechanism by which DM abolishes cardioprotection induced by sevoflurane postconditioning may be related to inhibited up-regulation of Mfn-2 expression in rats. Key words: Diabetes mellitus; Anesthetics, inhalation; Ischemic postconditioning; Myocardial reperfusion injury; Fusion proteins, bcr-abl

Effects of sevoflurane postconditioning on mitophagy during ischemia-reperfusion in rats

Objective To evaluate the effects of sevoflurane postconditioning on mitophagy during myocardial ischemia-reperfusion (I/R) in rats. Methods Forty-two pathogen-free adult male Sprague-Dawley rats, weighing 250-300 g, were randomly divided into 3 groups (n= 14 each) using a random number table: sham operation group (group S), I/R group and sevoflurane postconditioning group (group SP). Myocardial I/R was induced by 30 min ligation of the left anterior descending branch of the coronary artery followed by 2 h of reperfusion.In group SP, 2.4% sevoflurane was inhaled for 15 min starting from the onset of reperfusion, while 33% oxygen was inhaled in group I/R.The rats were sacrificed at the end of reperfusion, and the hearts were removed for measurement of myocardial infarct size (by 1% 2, 3, 5 triphenyltetrazolium chloride), expression of LC3Ⅱ/LC3Ⅰ, Beclin-1, p62 and Parkin (by Western blot), and mitochondrial membrane potential (by using JC-1 probe), and for examination of the ultrastructure of cardiomyocytes (with transmission electron microscope). Results Compared with group S, the myocardial infarct size was significantly increased, mitochondrial membrane potential was decreased, the expression of LC3Ⅱ/LC3Ⅰ, Beclin-1 and Parkin was up-regulated, and the expression of p62 was down-regulated in group I/R.Compared with group I/R, the myocardial infarct size was significantly decreased, the mitochondrial membrane potential was increased, and the expression of LC3Ⅱ/LC3Ⅰ, Beclin-1, p62 and Parkin was down-regulated in group SP. Conclusion Sevoflurane postconditioning can mitigate I/R injury in rats, and inhibition of excessive activation of mitophagy may be involved in the mechanism. Key words: Anesthetics, inhalation; Myocardial reperfusion injury; Mitochondria; Autophagy; Postconditioning

Protective Effect of Sevoflurane Postconditioning against Cardiac Ischemia/Reperfusion Injury via Ameliorating Mitochondrial Impairment, Oxidative Stress and Rescuing Autophagic Clearance.

Background and PurposeMyocardial infarction leads to heart failure. Autophagy is excessively activated in myocardial ischemia/reperfusion (I/R) in rats. The aim of this study is to investigate whether the protection of sevoflurane postconditioning (SPC) in myocardial I/R is through restored impaired autophagic flux.MethodsExcept for the sham control (SHAM) group, each rat underwent 30 min occlusion of the left anterior descending coronary (LAD) followed by 2 h reperfusion. Cardiac infarction was determined by 2,3,5-triphenyltetrazolium chloride triazole (TTC) staining. Cardiac function was examined by hemodynamics and echocardiography. The activation of autophagy was evaluated by autophagosome accumulation, LC3 conversion and p62 degradation. Potential molecular mechanisms were investigated by immunoblotting, real-time PCR and immunofluorescence staining.ResultsSPC improved the hemodynamic parameters, cardiac dysfunction, histopathological and ultrastructural damages, and decreased myocardial infarction size after myocardial I/R injury (P < 0.05 vs. I/R group). Compared with the cases in I/R group, myocardial ATP and NAD+ content, mitochondrial function related genes and proteins, and the expressions of SOD2 and HO-1 were increased, while the expressions of ROS and Vimentin were decreased in the SPC group (P < 0.05 vs. I/R group). SPC significantly activated Akt/mTOR signaling, and inhibited the formation of Vps34/Beclin1 complex via increasing expression of Bcl2 protein (P < 0.05 vs. I/R group). SPC suppressed elevated expressions of LC3 II/I ratio, Beclin1, Atg5 and Atg7 in I/R rat, which indicated that SPC inhibited over-activation of autophagy, and promoted autophagosome clearance. Meanwhile, SPC significantly suppressed the decline of Opa1 and increases of Drp1 and Parkin induced by I/R injury (P < 0.05 vs. I/R group). Moreover, SPC maintained the contents of ATP by reducing impaired mitochondria.ConclusionSPC protects rat hearts against I/R injury via ameliorating mitochondrial impairment, oxidative stress and rescuing autophagic clearance.

Sevoflurane post-conditioning increases nuclear factor erythroid 2-related factor and haemoxygenase-1 expression via protein kinase C pathway in a rat model of transient global cerebral ischaemia

The antioxidant mechanism of sevoflurane post-conditioning-induced neuroprotection remains unclear. We determined whether sevoflurane post-conditioning induces nuclear factor erythroid 2-related factor (Nrf2, a master transcription factor regulating antioxidant defence genes) and haemoxygenase-1 (HO-1, an antioxidant enzyme) expression, and whether protein kinase C (PKC) is involved in Nrf2 activation, in a rat model of transient global cerebral ischaemia/reperfusion (I/R) injury. Eighty-six rats were assigned to five groups: sham (n=6), control (n=20), sevoflurane post-conditioning (two cycles with 2 vol% sevoflurane inhalation for 10 min, n=20), chelerythrine (a PKC inhibitor; 5 mg kg(-1) i.v. administration, n=20), and sevoflurane post-conditioning plus chelerythrine (n=20). The levels of nuclear Nrf2 and cytoplasmic HO-1 were assessed 1 or 7 days after ischaemia (n=10 each, apart from the sham group, n=3). On day 1 but not day 7 post-ischaemia, Nrf2 and HO-1 expression were significantly higher in the sevoflurane post-conditioning group than in the control group. Chelerythrine administration reduced the elevated Nrf2 and HO-1 expression induced by sevoflurane post-conditioning. Sevoflurane post-conditioning increased Nrf2/HO-1 expression via PKC signalling in the early phase after transient global cerebral I/R injury, suggesting that activation of antioxidant enzymes may be responsible for sevoflurane post-conditioning-induced neuroprotection in the early phase after cerebral I/R injury.

Effects of sevoflurane postconditioning on myocardial oxidative stress in patients undergoing cardiac valve replacement with cardiopulmonary bypass

Objective To evaluate the effects of sevoflurane postconditioning on myocardial oxidative stress in the patients undergoing cardiac valve replacement with cardiopulmonary bypass (CPB).Methods Fifty ASA physical status Ⅱ or Ⅲ patients (NYHA Ⅱ or Ⅲ) of both sexes,aged 36-59 yr,weighing 42-71 kg,with rheumatic heart disease undergoing cardiac valve replacement under CPB,were randomly divided into control group (group C,n =25) and sevoflurane postconditioning group (group S,n =25).In group S,4 ％ sevoflurane was infused for 10 min via the extracorporeal circulation machines starting from the time point immediately after aortic unclamping.Before aortic clamping and at 15 min,30 min,6 h,and 24 h after aortic unclamping (T1-5),blood samples were collected from the central vein for determination of the levels of cardiac troponin I (cTnI) in plasma.Myocardial specimens were taken from the left auricle before CPB and after termination of CPB for determination of malondialdehyde (MDA) content and superoxide dismutase (SOD) activity.The restoration of spontaneous heart beat,reperfusion arrhythmia scores,and requirement for vasoactive drugs were recorded.Results Compared with group C,MDA content was significantly decreased,and SOD activity was increased after termination of CPB,the plasma cTnI concentration was decreased at T2-5,the rate of restoration of spontaneous heart beat was increased,reperfusion arrhythmia scores were decreased,and the requirement for dopamine and nitroglycerin was reduced in group S.Conclusion Sevoflurane postconditioning provides myocardial protection by reducing myocardial oxidative stress injury in the patients undergoing cardiac valve replacement with CPB. Key words: Oxidative stress ; Myocardium ; Sevoflurane

Effect of sevoflurane postconditioning on expression of optic atrophy-1 during myocardial ischemia-reperfusion in rats

Objective To evaluate the effect of sevoflurane postconditioning on expression of optic atrophy-1 (OPAl) during myocardial ischemia-reperfusion (I/R) in rats.Methods Forty-five healthy adult male Sprague-Dawley rats,aged 3 months,weighing 220-280 g,were randomly divided into 3 groups (n =15 each) using a random number table:sham operation group (group S),ischemia-reperfusion group (group I/R),and sevoflurane postconditioning group (group SP).Myocardial ischemia was induced by 30 min occlusion of left anterior descending branch of coronary artery followed by 120 min reperfusion.2.5 ％ sevoflurane was inhaled for 5 min starting from 29 min of ischemia until 4 min after beginning of reperfusion in SP group,while 33 ％ oxygen was inhaled in the other groups.Heart rate,systolic pressure and mean arterial pressure (MAP) were monitored and recorded and rate-pressure product (RPP) was calculated at 15 min before ischemia (T0),15 min of ischemia (T1),and 60 and 120 min of reperfusion (T2,3).At the end of reperfusion,the rats were sacrificed and the hearts were removed for determination of myocardial infarct size.The expression of OPAl mRNA and protein was measured by RT-PCR and immunohistochemistry,respectively.Their hearts were cut into sections which were stained with H.E.and examined under light microscope.Morphological changes of mitochondria were examined by electron microscopy.Results Compared with group S,MAP and RPP were significantly decreased at T1-3,the expression of OPA1 mRNA and protein was down-regulated,and the myocardial infarct size was increased in I/R and SP groups.Compared with group I/R,MAP and RPP were significantly decreased at T2,3,the expression of OPA1 mRNA and protein was up-regulated,and the myocardial infarct size was decreased in group SP.Conclusion Sevoflurane postconditioning can reduce myocardial I/R injury through up-regulating myocardial OPA1 expression,protecting mitochondrial morphology and inhibiting apoptosis in cardiomyocytes of rats. Key words: Anesthetics, inhalation; Myocardial reperfusion injury; Optic atrophy-1; Ischemic postconditioning

Delayed Remote Ischemic Preconditioning Produces an Additive Cardioprotection to Sevoflurane Postconditioning Through an Enhanced Heme Oxygenase 1 Level Partly Via Nuclear Factor Erythroid 2-Related Factor 2 Nuclear Translocation

Although both sevoflurane postconditioning (SPoC) and delayed remote ischemic preconditioning (DRIPC) have been proved effective in various animal and human studies, the combined effect of these 2 strategies remains unclear. Therefore, this study was designed to investigate this effect and elucidate the related signal mechanisms in a Langendorff perfused rat heart model. After 30-minute balanced perfusion, isolated hearts were subjected to 30-minute ischemia followed by 60-minute reperfusion except 90-minute perfusion for control. A synergic cardioprotective effect of SPoC (3% v/v) and DRIPC (4 cycles 5-minute occlusion/5-minute reflow at the unilateral hindlimb once per day for 3 days before heart isolation) was observed with facilitated cardiac functional recovery and decreased cardiac enzyme release. The infarct size-limiting effect was more pronounced in the combined group (6.76% ± 2.18%) than in the SPoC group (16.50% ± 4.55%, P < .001) or in the DRIPC group (10.22% ± 2.57%, P = .047). Subsequent analysis revealed that an enhanced heme oxygenase 1 (HO-1) expression, but not protein kinase B/AKt or extracellular signal-regulated kinase 1 and 2 activation, was involved in the synergic cardioprotective effect, which was further confirmed in the messenger RNA level of HO-1. Such trend was also observed in the nuclear factor erythroid 2-related factor 2 (Nrf2) nuclear translocation, an upstream regulation of HO-1. In addition, correlation analysis showed a significantly positive relationship between HO-1 expression and Nrf2 translocation (r = 0.729, P < .001). Hence, we conclude that DRIPC may produce an additive cardioprotection to SPoC through an enhanced HO-1 expression partly via Nrf2 translocation.

Effect of sevoflurane post-conditioning on PARP expression in cerebral cortex during focal cerebral ischemia/reperfusion in rats

Objective To investigate the effect of sevoflurane post-conditioning on the expression of poly (ADP-ribose) polymerase (PARP) in the cerebral cortex during focal cerebral ischemia/reperfusion (I/R) in rats and the mechanism.Methods Fifty-four male Sprague-Dawley rats,weighing 250-320 g,were randomly divided into3 groups (n =18 each) using a random number table:sham operation group (S group),I/R group and sevoflurane post-conditioning group (Sevo-pc group).The animals were anesthetized with intraperitoneal chloralhydrate 300 mg/kg.In Sevo-pc and I/R groups,focal cerebral ischemia was induced by middle cerebral artery occlusion using a nylon thread with rounded tip inserted into the right internal carotid artery and advanced cranially until resistance was met.The occlusion was maintained 1 h,followed by 24 h reperfusion.The animals in Sevo-pc group inhaled 2.7％ sevoflurane for 1 h starting from onset of reperfusion.At 24 h of reperfusion,neurological deficits were assessed,and then the rats were decapitated.The brains were immediately harvested for determination of the cerebral infarct size (by TTC staining) and expression of PARP in the ischemic cerebral cortex (by immunohistochemistry).The number of apoptotic cells was counted using TUNEL.The apoptosis index was calculated.Results Compared with group S,the neurological deficit scores and apoptotic cells were significantly increased,the cerebral infarct size was enlarged,and the expression of PARP in the ischemic cerebral cortex was up-regulated in I/R and Sevo-pc groups (P ＜ 0.05 or 0.01).The neurological deficit scores and apoptotic cells were significantly lower,the cerebral infarct size was smaller,and the expression of PARP in the ischemic cerebral cortex was downregulated in Sevo-pc group (P ＜ O.05 or 0.01).Conclusion Sevoflurane post-conditioning can reduce focal cerebral I/R injury in rats and down-regulation of PARP expression in the cerebral cortex may be involved in the mechanism. Key words: Anesthetics, inhalation; Reperfusion injury; Brain; PARP

Effects of sevoflurane postconditioning on lung function after cardiopulmonary bypass in patients undergoing cardiac valve replacement

Objective To evaluate the effects of sevoflurane postconditioning on lung function after cardiopulmonary bypass (CPB) in patients undergoing cardiac valve replacement.Methods Thirty ASA physical status Ⅱ or Ⅲ patients,aged 33-64 yr,weighing 47-81kg,scheduled for cardiac valve replacement with CPB,were equally and randomly divided into control group (group C) or sevoflurane postconditioning group (group S).Anesthesia was induced with iv injection of midazolam,etomidate,fentanyl and rocuronium.The patients were endotracheally intubated and mechanically ventilated.Anesthesia was maintained with intermittent iv boluses of midazolam,fentanyl and pipecuronium.In group S,2％ sevoflurane was washed into the membrane oxygenator at 2 min before aortic unclamping and continuously washed into the membrane oxygenator for 15 min after aortic unclamping.Before anesthesia (T1),immediately after sternum splitting (T2),at 30 min after termination of CPB (T3),and at 6,12 and 24h after operation (T4-6),blood samples were taken from the radial artery for blood gas analysis and PaO2 and SaO2 were recorded.Oxygen index (OI),alveolar-arterial oxygen tension difference (DA-aO2),dynamic pulmonary compliance (Cdyn) and static pulmonary compliance (Cstat) were calculated.Arterial blood samples were collected at T1,T3,T4 and T6 for determination of serum concentrations of IL-17A,neutrophil elastase (NE) and matrix metalloproteinase-9 (MMP-9).The time of mechanical ventilation after surgery and development of dyspnea,re-intubation and pulmonary rales were recorded.Results Compared with group C,OI at T4T6,PaO2 at T4 and T5,SaO2 at T3 and T6,Cdyn at T3 and T4 and Cstat at T4 were significantly increased,DAaO2 at T5 and T6,serum concentrations of IL-17A,NE and MMP-9 at T3,T4 and T6,and the incidence of pulmonary rales were decreased,and the time of mechanical ventilation was shortened (P ＜ 0.05),and no significant change was found in the incidence of dyspnea in group S (P ＞ 0.05).No re-intubation was required in the two groups.Conclusion Sevoflurane postconditioning can improve the lung function after CPB in patients undergoing cardiac valve replacement and inhibition of inflammatory responses may be involved in the mechanism. Key words: Anesthetics, inhalation; Respiratory function tests; Cardiopulmonary bypass; Heart valve prosthesis implantation