Sevoflurane post-conditioning reduces rat myocardial ischemia reperfusion injury through an increase in NOS and a decrease in phopshorylated NHE1 levels

Depletion of microRNA-92a Enhances the Role of Sevoflurane Treatment in Reducing Myocardial Ischemia-Reperfusion Injury by Upregulating KLF4

OBJECTIVE

As some articles have highlighted the role of microRNA-92a (miR-92a) in myocardial ischemia-reperfusion injury (MI/RI), this article aimed to investigate the effect of miR-92a on Sevoflurane (Sevo)-treated MI/RI via regulation of Krüppel-like factor 4 (KLF4).

METHODS

An MI/RI rat model was established by ligating the left anterior descending coronary artery. The cardiac function, pathological changes of myocardial tissues, inflammatory response, oxidative stress and cardiomyocyte apoptosis in MI/RI rats were determined. KLF4 and miR-92a expression was detected in the myocardial tissue of rats, and the target relationship between miR-92a and KLF4 was confirmed.

RESULTS

Sevo treatment alleviated myocardial damage, inflammatory response, oxidative stress response, and cardiomyocyte apoptosis, and improved cardiac function in MI/RI rats. miR-92a increased and KLF4 decreased in the myocardial tissue of MI/RI rats. KLF4 was targeted by miR-92a. Downregulation of miR-92a or upregulation of KLF4 further enhanced the effect of Sevo treatment on MI/RI.

CONCLUSION

This study suggests that depletion of miR-92a promotes upregulation of KLF4 to improve cardiac function, reduce cardiomyocyte apoptosis and further enhance the role of Sevo treatment in alleviating MI/RI.

Dexmedetomidine combined with propofol attenuates myocardial ischemia/reperfusion injury by activating the AMPK signaling pathway

Objective

Myocardial ischemia/reperfusion (MI/R) injury is a major cause of cardiac tissue damage, with high disability and death rates. Although both dexmedetomidine (Dex) and propofol (PPF) have been indicated to alleviate MI/R injury in rat models, the effects of the combined use of these two drugs remain unclear. This study aimed to investigate the combined effects of Dex and PPF against MI/R injury and related mechanisms.

Methods

A rat model of MI/R injury was established and used to explore the combined effects of Dex and PPF on MI/R injury. Hematoxylin-eosin (HE) and Masson staining were used for histopathological evaluation. 2,3,5-triphenyltetrazolium chloride (TTC), echocardiography, terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) staining were used to determine myocardial infarction size, cardiac function, and apoptosis, respectively. Enzyme-linked immunosorbent assay (ELISA) was performed to assess myocardial function and oxidative stress (OS). Autophagy was observed through transmission electron microscopy. Moreover, western blotting was conducted to detect autophagy markers and the AMPK pathway.

Results

The combination of Dex and PPF alleviated histopathological injury, reduced myocardial infarction, and rescued cardiac dysfunction in MI/R rats. Furthermore, Dex combined with PPF decreased the levels of MDA and ROS and increased the SOD level in MI/R rats. Besides, Dex combined with PPF inhibited myocardial apoptosis in MI/R rats. After combined treatment with Dex and PPF, the number of autophagosomes, expression levels of Beclin-1 and LC3II/LC3I were elevated, while the expression levels of p62 were reduced in MI/R rats. The combined use of Dex and PPF activated the AMPK pathway in MI/R rats. Compound C (an AMPK inhibitor) could abolish the combined effects of Dex and PPF on alleviating myocardial injury and enhancing autophagy in MI/R rats.

Conclusion

The combination of Dex and PPF attenuated MI/R injury in rats, which may be associated with the activation of the AMPK signaling pathway.

Regulation of autophagy of the heart in ischemia and reperfusion

Ischemia/reperfusion (I/R) of the heart leads to increased autophagic flux. Preconditioning stimulates autophagic flux by AMPK and PI3-kinase activation and mTOR inhibition. The cardioprotective effect of postconditioning is associated with activation of autophagy and increased activity of NO-synthase and AMPK. Oxidative stress stimulates autophagy in the heart during I/R. Superoxide radicals generated by NADPH-oxidase acts as a trigger for autophagy, possibly due to AMPK activation. There is reason to believe that AMPK, GSK-3β, PINK1, JNK, hexokinase II, MEK, PKCα, and ERK kinases stimulate autophagy, while mTOR, PKCδ, Akt, and PI3-kinase can inhibit autophagy in the heart during I/R. However, there is evidence that PI3-kinase could stimulate autophagy in ischemic preconditioning of the heart. It was found that transcription factors FoxO1, FoxO3, NF-κB, HIF-1α, TFEB, and Nrf-2 enhance autophagy in the heart in I/R. Transcriptional factors STAT1, STAT3, and p53 inhibit autophagy in I/R. MicroRNAs could stimulate and inhibit autophagy in the heart in I/R. Long noncoding RNAs regulate the viability and autophagy of cardiomyocytes in hypoxia/reoxygenation (H/R). Nitric oxide (NO) donors and endogenous NO could activate autophagy of cardiomyocytes. Activation of heme oxygenase-1 promotes cardiomyocyte tolerance to H/R and enhances autophagy. Hydrogen sulfide increases cardiac tolerance to I/R and inhibits apoptosis and autophagy via mTOR and PI3-kinase activation.

Lycium barbarum polysaccharide protects cardiomyocytes from hypoxia/reoxygenation injury via activation of SIRT3/CypD signaling

Background

Myocardial ischemia-reperfusion is a common pathological feature of many heart and vascular diseases, but the molecular mechanism of this process is still unclear, and there is no effective way to protect cardiomyocytes. The aim of this study was to examine the effects and underlying molecular mechanisms of Lycium barbarum polysaccharide (LBP) on myocardial ischemia-reperfusion injury in cardiomyocytes.

Methods

The cardiomyocyte cell line H9c2 were used to establish an in vitro hypoxia/reoxygenation (H/R) model. After treatment with LBP and/or the SIRT3 inhibitor 3-TYP, cell morphology was observed under the light microscopy. The Cell Counting Kit (CCK)-8 and 5-ethynyl-2'-deoxyuridine (EdU) assay were used to detect cell proliferation, and flow cytometry was performed to assess cell apoptosis. The lysine (166)-acetylation of CypD1 was determined by co-immunoprecipitation assay. Enzyme-linked immunosorbent assay (ELISA) was used to determine the lactate dehydrogenase (LDH) level in the culture medium. Na⁺-K⁺-ATPase activity, Ca²⁺-ATPase activity, and nitric oxide (NO) levels were measured.

Results

LBP alleviated cell damage and upregulated STIR3 expression in a dose-dependent manner. Upregulated SIRT3 expression and suppressed acetylation of CypD were also observed in H/R-induced H9c2 cells treated with LBP. Indeed, LBP remarkably reversed the inhibition of proliferation and cell apoptosis in H/R-induced H9c2 cells by activating SIRT3/CypD signaling. Blockade of SIRT3 with SIRT3 inhibitor (3-TYP) inhibited the protective effect of LBP on H9c2 cells. LBP markedly alleviated the H/R-induced increase of LDH release, and the decrease of Na⁺-K⁺-ATPase activity, Ca²⁺-ATPase activity, and NO levels. Inhibition of SIRT3 restored the protective effects of LBP.

Conclusions

LPB induced deacetylation of CypD by upregulating SIRT3, thereby protecting mitochondrial function and relieving H/R-induced injury in cardiomyocytes.

Induction of JAK2/STAT3 pathway contributes to protective effects of different therapeutics against myocardial ischemia/reperfusion

Insufficiency in coronary blood supply results in myocardial ischemia and consequently, various clinical syndromes and irreversible injuries. Myocardial damage occurs as a result of two processes during acute myocardial infarction (MI): ischemia and subsequent reperfusion. According to the available evidence, oxidative stress, excessive inflammation reaction, reactive oxygen species (ROS) generation, and apoptosis are crucial players in the pathogenesis of myocardial ischemia/reperfusion (IR) injury. There is emerging evidence that Janus tyrosine kinase 2 (JAK2) signal transducer and activator of the transcription 3 (STAT3) pathway offers cardioprotection against myocardial IR injury. This article reviews therapeutics that exert cardioprotective effects against myocardial IR injury through induction of JAK2/STAT3 pathway.

Role of sevoflurane in myocardial ischemia-reperfusion injury via the ubiquitin-specific protease 22/lysine-specific demethylase 3A axis

Myocardial ischemia-reperfusion injury (MIRI) represents a coronary artery disease, accompanied by high morbidity and mortality. Sevoflurane post-conditioning (SPC) is importantly reported in myocardial disease. Accordingly, the current study sought to evaluate the role of Sevo in MI/RI. Firstly, MI/RI models were established and subjected to SPC. Subsequently, pathological injury in the myocardium, myocardial infarction areas, H9c2 cell viability, apoptosis, and levels of creatine kinase-MB (CK-MB), cardiac troponin I (cTnI), and lactate dehydrogenase (LDH) were all measured. Ubiquitin-specific peptidase (22USP22), lysine-specific demethylase 3A (KDM3A), and Yes1 associated transcriptional regulator (YAP1) were down-regulated in H9c2 cells using cell transfection to verify their roles. The interaction between USP22 and KDM3A and between KDM3A and YAP1 was further validated. USP 22, KDM3A, and YAP1 were found to be down-regulated in MI/RI and SPC protected MI/RI rats, as evidenced by up-regulated expressions of USP22, KDM3A, and YAP1, reduced pathological injury in the myocardium, myocardial infarction areas, apoptosis, and levels of CK-MB, cTnI, and LDH, and enhanced H9c2 cell viability; while the protective effects of Sevo were counteracted by silencing of USP22, KDM3A, and SPC upregulated USP22, which stabilized KDM3A protein levels via deubiquitination, and KDM3A inhibited histone 3 lysine 9 di-methylation (H3K9me2) levels in the YAP1 promoter to encourage YAP1 transcription, to reduce MI/RI.

Promising Therapeutic Candidate for Myocardial Ischemia/Reperfusion Injury: What Are the Possible Mechanisms and Roles of Phytochemicals?

Percutaneous coronary intervention (PCI) is one of the most effective reperfusion strategies for acute myocardial infarction (AMI) despite myocardial ischemia/reperfusion (I/R) injury, causing one of the causes of most cardiomyocyte injuries and deaths. The pathological processes of myocardial I/R injury include apoptosis, autophagy, and irreversible cell death caused by calcium overload, oxidative stress, and inflammation. Eventually, myocardial I/R injury causes a spike of further cardiomyocyte injury that contributes to final infarct size (IS) and bound with hospitalization of heart failure as well as all-cause mortality within the following 12 months. Therefore, the addition of adjuvant intervention to improve myocardial salvage and cardiac function calls for further investigation. Phytochemicals are non-nutritive bioactive secondary compounds abundantly found in Chinese herbal medicine. Great effort has been put into phytochemicals because they are often in line with the expectations to improve myocardial I/R injury without compromising the clinical efficacy or to even produce synergy. We summarized the previous efforts, briefly outlined the mechanism of myocardial I/R injury, and focused on exploring the cardioprotective effects and potential mechanisms of all phytochemical types that have been investigated under myocardial I/R injury. Phytochemicals deserve to be utilized as promising therapeutic candidates for further development and research on combating myocardial I/R injury. Nevertheless, more studies are needed to provide a better understanding of the mechanism of myocardial I/R injury treatment using phytochemicals and possible side effects associated with this approach.

Upregulated microRNA-210-3p improves sevoflurane-induced protective effect on ventricular remodeling in rats with myocardial infarction by inhibiting ADCY9

Myocardial infarction (MI) is a significant cause of death and disability, and sevoflurane (sevo) can protect myocardium in clinic. We aim to assess the effects of miR-210-3p on MI rats undergoing sevo treatment with the involvement of adenylyl cyclase type 9 (ADCY9). Rat MI models were constructed by ligation of the left anterior descending, and the modeled rats were respectively treated with sevo, miR-210-3p agomir, antagomir, or overexpressed ADCY9. Then, miR-210-3p and ADCY9 expression, cardiac function, myocardial injury and fibrosis, and cardiomyocyte apoptosis in rats were evaluated. Target relation between miR-210-3p and ADCY9 was detected. miR-210-3p was downregulated while ADCY9 was upregulated in MI rats. Sevo was able to promote cardiac function and attenuate myocardial injury and fibrosis, as well as cardiomyocyte apoptosis in MI rats. These effects of sevo were strengthened by miR-210-3p elevation but abolished by miR-210-3p inhibition in MI rats. The role of elevated miR-210-3p in MI rats was reversed by overexpression of ADCY9. Upregulated miR-210-3p improves sevo-induced protective effect on ventricular remodeling in rats with MI through inhibiting ADCY9.

Cox-2 Antagonizes the Protective Effect of Sevoflurane on Hypoxia/Reoxygenation-Induced Cardiomyocyte Apoptosis through Inhibiting the Akt Pathway

Objective

To uncover the protective role of sevoflurane on hypoxia/reoxygenation-induced cardiomyocyte apoptosis through the protein kinase B (Akt) pathway.

Methods

An in vitro hypoxia/reoxygenation (H/R) model was established in cardiomyocyte cell line H9c2. Sevoflurane (SEV) was administrated in H9c2 cells during the reoxygenation period. Viability, layered double hydroxide (LDH) release, and apoptosis in H9c2 cells were determined to assess H/R-induced cell damage. Relative levels of apoptosis-associated genes were examined. Moreover, phosphorylation of Akt was determined.

Results

H/R injury declined viability and enhanced LDH release and apoptotic rate in H9c2 cells. Cyclooxygenase-2 (Cox-2) was upregulated following H/R injury, which was partially reversed by SEV treatment. In addition, SEV treatment reversed changes in viability and LDH release owing to H/R injury in H9c2 cells, which were further aggravated by overexpression of Cox-2. The Akt pathway was inhibited in H9c2 cells overexpressing Cox-2.

Conclusions

Sevoflurane protects cardiomyocyte damage following H/R via the Akt pathway, and its protective effect was abolished by overexpression of Cox-2.

Mitochondrial Quality Control in Cardiac-Conditioning Strategies against Ischemia-Reperfusion Injury

Mitochondria are the central target of ischemic preconditioning and postconditioning cardioprotective strategies, which consist of either the application of brief intermittent ischemia/reperfusion (I/R) cycles or the administration of pharmacological agents. Such strategies reduce cardiac I/R injury by activating protective signaling pathways that prevent the exacerbated production of reactive oxygen/nitrogen species, inhibit opening of mitochondrial permeability transition pore and reduce apoptosis, maintaining normal mitochondrial function. Cardioprotection also involves the activation of mitochondrial quality control (MQC) processes, which replace defective mitochondria or eliminate mitochondrial debris, preserving the structure and function of the network of these organelles, and consequently ensuring homeostasis and survival of cardiomyocytes. Such processes include mitochondrial biogenesis, fission, fusion, mitophagy and mitochondrial-controlled cell death. This review updates recent advances in MQC mechanisms that are activated in the protection conferred by different cardiac conditioning interventions. Furthermore, the role of extracellular vesicles in mitochondrial protection and turnover of these organelles will be discussed. It is concluded that modulation of MQC mechanisms and recognition of mitochondrial targets could provide a potential and selective therapeutic approach for I/R-induced mitochondrial dysfunction.

Cholinergic receptors play a role in the cardioprotective effects of anesthetic preconditioning: Roles of nitric oxide and the CaMKKβ/AMPK pathway

Vagus nerve activation may have important therapeutic significance for myocardial ischemia-reperfusion (IR) injury. Nitric oxide (NO) plays a vital role in the cardioprotective effects of anesthetic preconditioning (APC). Moreover, acetylcholine (ACh) prevents cardiomyocyte damage by activating AMP-activated protein kinase (AMPK) and increasing the phosphorylation of Ca2+/calmodulin-dependent protein kinase β (CaMKKβ). The aim of the present study was to determine whether APC could protect heart function by antagonizing IR damage via the cholinergic system. It was hypothesized that the NO synthase (NOS)/CaMKKβ/AMPK pathway might be involved in the cardioprotective effects induced by cholinergic receptor activation. Isolated rat hearts were subjected to ischemia for 30 min followed by 120 min of reperfusion. Volatile anesthetic sevoflurane (3.5%) was administered for 15 min before ischemia, then rinsed for 15 min. The muscarinic acetylcholine receptor (mAChR) antagonist atropine (ATR; 100 nM) and the nicotinic acetylcholine receptor (nAChR) antagonist hexamethonium (HEM; 50 µM) were administered 10 min before APC. Both mAChR and nAChR were involved in APC-induced cardioprotection. ATR and HEM treatment both abolished the protective effects of APC on IR damage in isolated hearts, demonstrating the importance of cholinergic receptors in the protection mechanism of APC. The present study thus suggests that APC plays a cardioprotective role, in part, by regulating neurohumoral pathways. In addition, there may be functional coupling between the two cholinergic receptors, and the NOS and CaMKKβ/AMPK pathways may play roles in shared pathways that mediate the cardioprotective effects of APC. These findings may provide insight into potential new mechanisms of APC-induced cardioprotection against IR injury.

Cardioprotective Effect of Anesthetics: Translating Science to Practice

Cardiovascular diseases are the number one cause of mortality in the world, particularly among the aging population. Major adverse cardiac events are also a major contributor to perioperative complications, affecting 2.6% of noncardiac surgeries and up to 18% of cardiac surgeries. Cardioprotective effects of volatile anesthetics and certain intravenous anesthetics have been well-documented in preclinical studies; however, their clinical application has yielded conflicting results in terms of their efficacy. Therefore, better understanding of the underlying mechanisms and developing effective ways to translate these insights into clinical practice remain significant challenges and unmet needs in the area. Several recent reviews have focused on mechanistic dissection of anesthetic-mediated cardioprotection. The present review focuses on recent clinical trials investigating the cardioprotective effects of anesthetics in the past five years. In addition to highlighting the main outcomes of these trials, the authors provide their perspectives about the current gap in the field and potential directions for future investigations.

Autophagic Network Analysis of the Dual Effect of Sevoflurane on Neurons Associated with GABARAPL1 and 2

Background

Sevoflurane is commonly used as a general anesthetic in neonates to aged patients. Preconditioning or postconditioning with sevoflurane protects neurons from excitotoxic injury. Conversely, sevoflurane exposure induces neurotoxicity during early or late life. However, little is known about the underlying mechanism of the dual effect of sevoflurane on neurons. Autophagy is believed to control neuronal homeostasis. We hypothesized that autophagy determined the dual effect of sevoflurane on neurons.

Methods

DTome was used to identify the direct protein target (DPT) of sevoflurane. The STRING database was employed to investigate the proteins associated with the DPTs. Protein-protein interaction was assessed using Cytoscape. WebGestalt was used to analyze gene set enrichment. The linkage between candidate genes and autophagy was identified using GeneCards.

Results

This study found that 23 essential DPTs of sevoflurane interacted with 77 proteins from the STRING database. GABARAPL1 and 2, both of which are DPT- and autophagy-associated proteins, were significantly expressed in the brain and enriched in GABAergic synapses.

Conclusions

Taken together, our findings showed that the network of sevoflurane-DPT-GABARAPL1 and 2 is related to the dual effect of sevoflurane on neurons.

Sevoflurane attenuates cardiomyocyte apoptosis by mediating the miR-219a/AIM2/TLR4/MyD88 axis in myocardial ischemia/reperfusion injury in mice

Myocardial infarction (MI) is a vital cause of death and disability globally. The primary treatment for diminishing acute myocardial ischemic injury is myocardial reperfusion, which may induce cardiomyocyte death. Our aim is to unravel the mechanism of sevoflurane (Sev) in microRNA-219a (miR-219a)-mediated regulation of absent in melanoma 2 (AIM2) and TLR4/MyD88 pathway during myocardial ischemia/reperfusion (I/R). The area of MI and apoptosis of cardiomyocytes of the developed mouse model were evaluated by TTC staining and TUNEL, respectively. After the determination of miR-219a as our target using microarray analysis, miR-219a atagomiR was used to treat the mouse model. The luciferase assay verified whether miR-219a targeted AIM2, and the miR-219a and AIM2 expression in myocardial tissues was detected by RT-qPCR and Western blot. miR-219a was significantly increased in myocardial tissues from mice treated with Sev, and the area of MI and cardiomyocyte apoptosis were decreased as a consequence. The miR-219a inhibitor reversed the action of Sev. Moreover, overexpression of AIM2 or induction of the TLR4 pathway aggravated myocardial I/R injury alleviated by miR-219a. All in all, the treatment of Sev upregulated miR-219a expression, which blocked the TLR4 pathway by targeting AIM2 and attenuated cardiomyocyte apoptosis in myocardial I/R mouse model.

Calycosin-7-O-β-D-glucoside attenuates myocardial ischemia-reperfusion injury by activating JAK2/STAT3 signaling pathway via the regulation of IL-10 secretion in mice

Calycosin-7-O-β-D-glucoside (CG) is the component of Astragali Radix, and the aim of the present study is to investigate whether CG protects myocardium from I/R-induced damage by the regulation of IL-10/JAK2/STAT3 signaling pathway. H9C2 cells were subjected to I/R treatment and pretreated with 1 μm CG in vitro. In addition, a mouse model of myocardial I/R injury was induced by left anterior descending (LAD) coronary artery ligation and administrated with 30 mg/kg CG by intravenous injection before I/R surgery. In vitro and in vivo results showed that CG up-regulated IL-10 level, activated the JAK2/STAT3 pathway, and protected myocardial cells from I/R-induced apoptosis. The hemodynamic measurement, TTC staining, TUNEL staining, and western blot results in vivo showed that the protective effects of CG on myocardial function and cell apoptosis were all reversed by the IL-10R α neutralizing antibody. CG-induced phosphorylation activation of JAK2/STAT3 signaling pathway was also suppressed by the blocking of IL-10. In summary, these findings suggest that CG might alleviate myocardial I/R injury by activating the JAK2/STAT3 signaling pathway via up-regulation of IL-10 secretion, which provides us insights into the mechanism underlying the protective effect of CG on myocardial I/R injury.

Sevoflurane Alleviates Reperfusion Arrhythmia by Ameliorating TDR and MAPD90 in Isolated Rat Hearts after Ischemia-Reperfusion

Objective

To investigate the effect of sevoflurane on the monophasic action potentials (MAPs) in isolated rat hearts after ischemia-reperfusion.

Methods

Twenty-four healthy SD male rats, weighing 280–320 g, were randomly divided into three groups after successful preparation of a Langendorff isolated heart perfusion model with a stabilization period perfusion of 15 min with Krebs–Henseleit (K–H) fluid (n = 8): the control group (group A, continuously perfused with K–H fluid for 105 min), the ischemia-reperfusion group (group B, continuously perfused with K–H fluid for 15 min, and then exposed to 60 min of global ischemia induced by Thomas solution followed by 30 min of reperfusion), and the sevoflurane group (group C, K–H fluid contained 1.0 MAC sevoflurane, and other procedures were same as in group B). Heart rate (HR) and MAPs including time course (MAPD₅₀ or MAPD₉₀) of the epicardium (Epi) and endocardium (Endo) were recorded at the time of balance perfusion for 15 min (T₀), continuous perfusion for 15 min (T₁), reperfusion for 15 min/continuous perfusion for 105 min (T₂), and reperfusion for 30 min/continuous perfusion for 120 min (T₃), and the transmural dispersion of repolarization (TDR) was calculated. The incidence of arrhythmia, time for restoration of spontaneous heart beat, and duration of arrhythmia were recorded during the period of reperfusion.

Results

HR in group B and group C was lower at T₂ and T₃ than that in group A, while that in group B was significantly lower than that in group A at T₂ and T₃, and HR in group C was higher than that in group B at T₂ and T₃ (P < 0.05). There was no difference of TDR in each group at T₀ and T₁ (P > 0.05), while TDR in group B was increased at T₂ and T₃ compared with that in group C and group A (P < 0.05). TDR in group C was decreased compared with that in group B at T₂ and T₃ (P < 0.05), while there was no such difference between group C and group A (P > 0.05). The time for restoration of spontaneous heart beat and duration of arrhythmia in group C were shorter than those in group B (P < 0.05), while cardiac arrhythmia scores in group B were higher than those in group C (P < 0.05). There was no difference of MAPD₅₀ in each group (P > 0.05). The MAPD₉₀ in group B was much longer than that in other groups at T₂ and T₃ (P < 0.05), while there was no such difference between group C and group A (P > 0.05). The prolonged MAPD₉₀ at T₂ and T₃ in group B strikingly differed from that at T₀ and T₁ (P < 0.05). Nevertheless, there was no such difference in other groups at different time points (P > 0.05).

Conclusion

Sevoflurane alleviates reperfusion arrhythmia induced by myocardial ischemia-reperfusion through the shortening of MPAD₉₀ in isolated rat hearts.

Effects of isoflurane on complex II‑associated mitochondrial respiration and reactive oxygen species production: Roles of nitric oxide and mitochondrial KATP channels

Volatile anesthetics may protect the heart against ischemia‑reperfusion injury via the direct action on mitochondrial complexes and by regulating the production of reactive oxygen species (ROS). Recently, we reported that isoflurane induced the attenuation of mitochondrial respiration caused by complex I substrates. This process was not associated with endogenous production of mitochondrial nitric oxide (NO). In the present study, we investigated the effects of isoflurane on mitochondrial respiration and ROS production using complex II substrates. The detailed mechanism of these effects was explored with regards to NO production and the expression of mitochondrial ATP‑dependent K+ (mKATP) channels. Mitochondria were isolated from the heart of Sprague‑Dawley rats. The respiratory rates of mitochondria (0.5 mg/ml) were measured via polarography at 28˚C with computer‑controlled Clark‑type O2 electrodes. The complex II substrate succinate (5 mM) was used; 0.25 mM of isoflurane was administered prior to ADP‑initiated state 3 respiration. The mitochondrial membrane potential (ΔΨm) was measured under treatment with the substrate succinate, or succinate in the presence of the complex I inhibitor rotenone. The detection was achieved in a cuvette‑based spectrophotometer operating at wavelengths of 503 nm (excitation) 527 nm (emission) in the presence of 50 nM of the fluorescent dye rhodamine 123. The H2O2 release rates in the mitochondria were measured spectrophotometrically with succinate, or succinate and rotenone using the fluorescent dye Amplex red (12.5‑25 µM). The results indicated that isoflurane increased the state 3 and 4 respiration rates caused by succinate, which were higher than those noted in the control group in the presence of succinate alone. The NOS inhibitor L‑NIO or the NO‑sensitive guanylyl cyclase 1H‑[1,2,4]oxadiazolo[4,3‑a]quinoxalin‑1‑one did not inhibit the increase in the respiration rate (state 3) induced by isoflurane. The ROS scavengers SPBN and manganese (III) tetrakis (4‑benzoic acid) porphyrin chloride inhibited the increase in the respiration rate (state 3 and 4) induced by isoflurane. This effect was not noted for the putative KATP channel blockers 5‑hydroxydecanoic acid and glibenclamide. Isoflurane caused a greater decrease in the concentration of H2O2 during ADP‑initiated state 3 respiration, and L‑N5‑(1‑Iminoethyl)‑ornithine did not inhibit this effect. In conclusion, isoflurane was determined to modulate mitochondrial respiration and ROS production caused by the complex II substrate succinate. These effects were independent of endogenous mitochondrial NO generation and mitochondrial KATP channel opening.

Over-expression of JAZF1 promotes cardiac microvascular endothelial cell proliferation and angiogenesis via activation of the Akt signaling pathway in rats with myocardial ischemia-reperfusion

Myocardial ischemia-reperfusion (I/R) injury is caused by endothelial dysfunction and enhanced oxidative stress. The overexpression of JAZF1, a zinc finger protein, has been reported to promote cell proliferation and suppress myogenic differentiation in type 2 diabetes. However, the involvement of JAZF1 in myocardial I/R injury remains to be unclear. The current study aims to investigate the role by which JAZF1 influences cardiac microvascular endothelial cells (CMECs) in a rat model of myocardial I/R injury. A total of 50 rats were established as a myocardial I/R model to isolate CMECs, with alterations in JAZF1 expression. After that, the gain- or loss-function of JAZF1 on the proliferation, apoptosis and tube formation ability of CMECs were evaluated by a series of in vitro experiments. Results indicated that JAZF1 was down-regulated in CMECs of rats with myocardial I/R injury. After treatment with JAZF1, the levels of VEGF, Bcl-2, PDGF and p-Akt/Akt were all increased; however, the expression of Bax, caspase-3, caspase-9, p-Bad/Bad, c-caspase-3/caspase-3, c-caspase-9/caspase-9, and p-FKHR/FKHR exhibited decreased levels; CMEC proliferation and angiogenesis were increased, while cell apoptosis was attenuated. CMECs transfected with JAZF1 shRNA exhibited the contrary tendencies. The key findings of this study suggest that the over-expression of JAZF1 alleviates myocardial I/R injury by enhancing proliferation and angiogenesis of CMECs and in turn inhibiting apoptosis of CMECs via the activation of the Akt signaling pathway.

Sevoflurane postconditioning alleviates hypoxia-reoxygenation injury of cardiomyocytes by promoting mitochondrial autophagy through the HIF-1/BNIP3 signaling pathway

Background

Sevoflurane postconditioning (SpostC) can alleviate hypoxia-reoxygenation injury of cardiomyocytes; however, the specific mechanism remains unclear. This study aimed to investigate whether SpostC promotes mitochondrial autophagy through the hypoxia-inducible factor-1 (HIF-1)/BCL2/adenovirus E1B 19-kDa-interacting protein 3 (BNIP3) signaling pathway to attenuate hypoxia-reoxygenation injury in cardiomyocytes.

Methods

The H9C2 cardiomyocyte hypoxia/reoxygenation model was established and treated with 2.4% sevoflurane at the beginning of reoxygenation. Cell damage was determined by measuring cell viability, lactate dehydrogenase activity, and apoptosis. Mitochondrial ultrastructural and autophagosomes were observed by transmission electron microscope. Western blotting was used to examine the expression of HIF-1, BNIP3, and Beclin-1 proteins. The effects of BNIP3 on promoting autophagy were determined using interfering RNA technology to silence BNIP3.

Results

Hypoxia-reoxygenation injury led to accumulation of autophagosomes in cardiomyocytes, and cell viability was significantly reduced, which seriously damaged cells. Sevoflurane postconditioning could upregulate HIF-1α and BNIP3 protein expression, promote autophagosome clearance, and reduce cell damage. However, these protective effects were inhibited by 2-methoxyestradiol or sinBNIP3.

Conclusion

Sevoflurane postconditioning can alleviate hypoxia-reoxygenation injury in cardiomyocytes, and this effect may be achieved by promoting mitochondrial autophagy through the HIF-1/BNIP3 signaling pathway.

Downregulation of microRNA-155 stimulates sevoflurane-mediated cardioprotection against myocardial ischemia/reperfusion injury by binding to SIRT1 in mice

OBJECTIVE

The inhaled sevoflurane has been demonstrated to protect against myocardial ischemia/reperfusion (I/R) injury. However, the relative mechanisms of sevoflurane-mediated cardioprotection remain largely unknown. This study intends to explore the effect of miR-155 on the sevoflurane-mediated cardioprotection by regulating Sirtuin 1 (SIRT1) in mouse models of myocardial I/R.

METHODS

Left anterior descending coronary artery ligation was used to induce models of myocardial I/R in mice. The I/R mice were treated with sevoflurane, sevoflurane + mimics negative control (NC) or sevoflurane + miR-155 mimics. The expression of microRNA-155 (miR-155) and SIRT1 was examined by quantitative real-time polymerase chain reaction and Western blot assay. Then cardiac functions and hemodynamic alterations were evaluated. Evans blue-2,3,5-triphenyltetrazolium chloride and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay staining methods were adopted to evaluate infarct size and cardiomyocyte apoptosis, respectively.

RESULTS

In the I/R mice, miR-155 was expressed at a high level and SIRT1 at a low level. SIRT1 was confirmed to be a target gene of miR-155. The treatment of sevoflurane could reduce miR-155 expression and increased SIRT1 expression in the myocardial tissues, under which conditions, cardiac functions were promoted, accompanied by reduced infarct size and inhibited cardiomyocyte apoptosis. In response to miR-155 upregulation, the sevoflurane-treated I/R mice showed reduced cardiac functions, and increased infarct size and cardiomyocyte apoptosis.

CONCLUSION

The findings obtained in this study provide evidence suggesting that miR-155 targets and negatively regulates SIRT1 expression, a mechanism by which the protection of sevoflurane is inhibited against myocardial I/R in mice.

Cardioprotective Effect of Isosorbide Dinitrate Postconditioning Against Rat Myocardial Ischemia-Reperfusion Injury In Vivo

BACKGROUND This study investigated the cardioprotective effect of isosorbide dinitrate (ISDN) postconditioning against rat myocardial ischemia/reperfusion injury in vivo and provided a theoretical basis for clinical application. MATERIAL AND METHODS We randomly divided 32 Wistar rats into 4 groups: sham group, I/R (ischemia/reperfusion) group, I-PostC group (with 3 cycles of 30 s reperfusion and 30 s reocclusion applied at the onset of reperfusion), and P-PostC group (nitrate postconditioning: isosorbide dinitrate (5mg/kg) was given 1 min before reperfusion). The left anterior descending artery (LAD) was occluded for 40 min, followed by a 180-min reperfusion. Relevant indicators were tested. The LAD was occluded again, then we determined the myocardial infarct size. Paraffinized sections were prepared and TUNEL detection was performed. RESULTS There were no significant differences in ischemic sizes between different groups. Compared with the I/R group, the levels of cTnI and myocardial infarct size in the I-PostC group and P-PostC group were significantly decreased (p<0.05). However, there were no significant difference between the I-PostC group and P-PostC group. Compared with the sham-operated group, the levels of cTnI and MDA in the I/R group, I-PostC group, and P-PostC group were significantly increased (p<0.05) and the levels of SOD were significantly decreased (p<0.05). Compared with the I/R group, I-PostC and P-PostC decreased the level of MDA and increased the level of SOD (both P<0.05). CONCLUSIONS ISDN postconditioning induces a similar cardioprotective effect as I-PostC. The potential mechanisms of cardioprotection of ISDN postconditioning might be via improvement of myocardial antioxidant capacity and reduced generation of reactive oxygen species.

Sevoflurane postconditioning protects against myocardial ischemia/reperfusion injury by restoring autophagic flux via an NO-dependent mechanism

Volatile anesthetics improve postischemic cardiac function and reduce infarction even when administered for only a brief time at the onset of reperfusion. A recent study showed that sevoflurane postconditioning (SPC) attenuated myocardial reperfusion injury, but the underlying mechanisms remain unclear. In this study, we examined the effects of sevoflurane on nitric oxide (NO) release and autophagic flux during the myocardial ischemia/reperfusion (I/R) injury in rats in vivo and ex vivo. Male rats were subjected to 30 min ischemia and 2 h reperfusion in the presence or absence of sevoflurane (1.0 minimum alveolar concentration) during the first 15 min of reperfusion. We found that SPC significantly improved hemodynamic performance after reperfusion, alleviated postischemic myocardial infarction, reduced nicotinamide adenine dinucleotide content loss, and cytochrome c release in heart tissues. Furthermore, SPC significantly increased the phosphorylation of endothelial nitric oxide synthase (NOS) and neuronal nitric oxide synthase, and elevated myocardial NOS activity and NO production. All these effects were abolished by treatment with an NOS inhibitor NG-nitro-L-arginine methyl ester (L-NAME, 10 mg/kg, i.v.). We also observed myocardial I/R-induced accumulation of autophagosomes in heart tissues, as evidenced by increased ratios of microtubule-associated protein 1 light chain 3 II/I, up-regulation of Beclin 1 and P62, and reduced lysosome-associated membrane protein-2 expression. SPC significantly attenuated I/R-impaired autophagic flux, which were blocked by L-NAME. Moreover, pretreatment with the autophagic flux blocker chloroquine (10 mg/kg, i.p.) increased autophagosome accumulation in SPC-treated heart following I/R and blocked SPC-induced cardioprotection. The same results were also observed in a rat model of myocardial I/R injury ex vivo, suggesting that SPC protects rat hearts against myocardial reperfusion injury by restoring I/R-impaired autophagic flux via an NO-dependent mechanism.

Downregulation of the long noncoding RNA MBNL1-AS1 protects sevoflurane-pretreated mice against ischemia-reperfusion injury by targeting KCNMA1

Total knee arthroplasty (TKA) is the most common and cost-effective treatment for older adults with long-standing osteoarthritis. During TKA, muscle cells suffer from prolonged oxygen deficiency, which leads to altered cell metabolism that reduces the energy demand and maintains cell homeostasis before blood flow is restored. This study focused on the role of the lncRNA muscleblind-like 1 antisense RNA 1 (MBNL1-AS1) in protecting sevoflurane-pretreated mice against ischemia-reperfusion (I/R) injury after TKA, as well as the elucidation of the potential associated mechanism. Identification of differentially expressed lncRNAs was performed using the microarray dataset GSE21164, which was extracted from the GEO database. Target genes of the lncRNA were determined using Multi-Experiment Matrix (MEM), a dual-luciferase reporter gene assay, and KEGG enrichment analyses. The results showed that MBNL1-AS1 was overexpressed in skeletal muscle cells in mice, while KCNMA1, which was enriched in the cGMP-PKG signaling pathway, was negatively regulated by MBNL1-AS1. Furthermore, I/R mice displayed serious inflammatory reactions. Down-regulation of MBNL1-AS1 increased the expression of KCNMA1, PKGII, VASP, VEGF, Bcl-2, Cyclin D1, Cyclin D3, and Cdc 42 but decreased the expression of Bax, cleaved caspase-3, and cleaved PARP. Furthermore, upon MBNL1-AS1 upregulation, the rate of cell apoptosis increased while the rate of cell proliferation decreased. Our data suggested that down-regulated lncRNA MBNL1-AS1 might promote the proliferation and inhibit the apoptosis of skeletal muscle cells by upregulating KCNMA1 expression via activation of the cGMP-PKG signaling pathway, thus protecting sevoflurane-pretreated mice against I/R injury after TKA.

A potential therapeutic target identified by researchers in China could help limit damage to tissues following osteoarthritic knee surgery. A total knee arthroplasty can alleviate symptoms of end-stage osteoarthritis, but the surgery requires use of a tourniquet. This temporarily cuts blood supply to tissues and can trigger severe ischemia-reperfusion (I/R) injury, tissue damage caused by blood flow returning after oxygen deficiency. Shao-Nan Yu and co-workers at the China-Japan Union Hospital of Jilin University, Changchun, demonstrated that lowering expression of a particular RNA molecule following surgery could limit I/R damage. They found that the molecule was over-expressed in mice during I/R injury. This overexpression limited activation of a signalling pathway and an associated protein vital to the chemical balance of cell membranes and healthy muscle cell contraction.

Propofol and sevoflurane combined with remifentanil on the pain index, inflammatory factors and postoperative cognitive function of spine fracture patients

The effects of propofol vs. sevoflurane combined with remifentanil on the pain index, inflammatory factors and postoperative cognitive function in spine fracture patients were studied and analyzed. A total of 62 patients with vertebral fracture were randomly divided into the propofol group (P group, n=41) and the sevoflurane group (S group, n=41). P group used induction anesthesia with propofol, and maintained anesthesia via intravenous injection of remifentanil. While patients in S group received induction anesthesia with sevoflurane, and also remifentanil as the maintained anesthesia. Results showed that extubation time, eye-opening time and response time of P group were lower than S group (p<0.05). The VAS score 48 h after surgery in P group was significantly lower than the S group (p<0.05). Levels of IL-6, IL-1β, ICAM-1 and MMP-9 in serum in P group were lower than those in S group (p<0.05). Mini-mental state examination (MMSE) score 24 h after surgery in P group was higher than that in S group (p<0.01). Compared with sevoflurane anesthesia, propofol combined with remifentanil anesthesia on spine fracture patients can significantly decrease the pain index and inflammatory reaction, shorten the postoperative recovery time.

Effect of sevoflurane on the ATPase activity of hippocampal neurons in a rat model of cerebral ischemia-reperfusion injury via the cAMP-PKA signaling pathway

We aim to investigate the effects of sevoflurane on the ATPase activity of the hippocampal neurons in rats with cerebral ischemia-reperfusion injury (IRI) via the cyclic adenosine monophosphate (cAMP) and protein kinase A (PKA) signaling pathway. Sixty rats were assigned into the normal, model and sevoflurane groups (n = 20, the latter two groups were established as focal cerebral IRI models). The ATPase activity was detected using an ultramicro Na (+)-K (+)-ATP enzyme kit. Immunohistochemical staining was used to detect the positive protein expression of cAMP and PKA. The hippocampal neurons were assigned to the normal, IRI, IRI + sevoflurane, IRI + forskolin, IRI + H89 and IRI + sevoflurane + H89 groups. qRT-PCR and Western blotting were performed for the expressions of cAMP, PKA, cAMP-responsive element-binding protein (CREB) and brain derived neurotrophic factor (BDNF). The normal and sevoflurane groups exhibited a greater positive protein expression of cAMP and PKA than the model group. Compared with the normal group, the expressions of cAMP, PKA, CREB and BDNF all reduced in the IRI, model and IRI + H89 groups. The sevoflurane group showed higher cAMP, PKA, CREB and BDNF expressions than the model group. Compared with the IRI group, ATPase activity and expressions of cAMP, PKA, CREB and BDNF all increased in the normal, IRI + sevoflurane and IRI + forskolin groups but decreased in the IRI + H89 group. It suggests that sevoflurane could enhance ATPase activity in hippocampal neurons of cerebral IRI rats through activating cAMP-PKA signaling pathway.

Deferoxamine-activated hypoxia-inducible factor-1 restores cardioprotective effects of sevoflurane postconditioning in diabetic rats

AIM

The cardioprotective effects of sevoflurane postconditioning (SpostC) are eliminated under diabetic conditions, and the underlying mechanism for this phenomenon remains unclear. Many studies have demonstrated that the hypoxia-inducible factor-1 (HIF-1) signalling pathway in the myocardium is impaired under diabetic conditions. This study was to investigate whether deferoxamine (DFO)-induced activation of HIF-1 signalling pathway can restore the cardioprotective effects of SpostC in diabetic rats.

METHODS

A model of myocardial ischaemia/reperfusion (I/R) injury was induced via ligation of the left anterior descending artery. SpostC was conducted by administering 1.0 MAC sevoflurane. After inducing the I/R injury, the following parameters were measured: myocardial infarct size, cardiac function, myocardial ultrastructure, mitochondrial respiratory function, respiratory chain enzyme activity, rate of reactive oxygen species (ROS) generation, and protein expression of HIF-1α, vascular endothelial growth factor (VEGF), cleaved caspase-3, Bcl-2 and Bax.

RESULTS

After DFO activated HIF-1 in the impaired myocardium of diabetic rats, SpostC significantly upregulated the protein expression of HIF-1α and its downstream mediator VEGF. This improved myocardial mitochondrial respiratory function and respiratory chain enzyme activity and reduced ROS generation as well as the protein expression of cleaved caspase-3 and Bax. As a result, myocardial infarct size decreased, and cardiac function and mitochondrial ultrastructure improved.

CONCLUSION

This study demonstrates for the first time that abolishment of the cardioprotective effects of SpostC in diabetic rats is associated with impairment of the HIF-1 signalling pathway and that DFO can activate HIF-1 to restore these cardioprotective effects of SpostC in diabetic rats.

Trichostatin A attenuates oxidative stress-mediated myocardial injury through the FoxO3a signaling pathway

Trichostatin A (TSA), a histone deacetylase inhibitor, is widely used as an anticancer drug. Recently, TSA has been shown to exert a protective effect on ischemia/reperfusion (I/R) injury; however, the underlying mechanisms remain unclear. Forkhead box O3a (FoxO3a), a unique FoxO family member, has been shown to attenuate myocardial injury by increasing resistance to oxidative stress in mice. The present study aimed to investigate whether TSA exerts its cardioprotective effects through the FoxO3a signaling pathway. For this purpose, healthy male Wistar rats were pre-treated with TSA for 5 days before they were subjected to ligation/relaxation of the left anterior descending branch of the coronary artery and to 30 min of ischemia, followed by 24 h of reperfusion. The activities of creatine kinase (CK), lactate dehydrogenase (LDH), aspartate aminotransferase (AST) and superoxide diamutase (SOD), as well as the malondialdehyde (MDA) levels were examined. The H9c2 rat myocardial cell line was cultured in 10% FBS-containing DMEM for 24 h. The cells were incubated with/without TSA (50 nmol/l) for 1 h and then incubated with/without H₂O₂ (400 µM) for 2 h. Reactive oxygen species (ROS) and mitochondrial membrane potential (Δψm) were measured by probe staining in the H9c2 cells. The expression of FoxO3a, mitochondrial SOD2 and catalase was quantified by western blot analysis. The levels of H3 and H4 acetylation of the FoxO3a promoter region were examined by chromatin immunoprecipitation assay. TSA significantly reduced the myocardial infarct size and the activities of serum LDH, AST and CK in the rats. TSA also decreased the levels of MDA and increased the activities of SOD in the myocardial tissue of the rats. Consistent with the reduced injury to the TSA-treated rats, TSA significantly reduced the H₂O₂-induced levels of ROS and increased Δψm. In addition, TSA increased the expression of FoxO3a, SOD2 and catalase, which may be related to increasing the level of H4 acetylation of the FoxO3a promoter region. Our results thus revealed that TSA protected the myocardium from oxidative stress-mediated damage by increasing H4 acetylation of the FoxO3a promoter region, and the expression of FoxO3a, SOD2 and catalase.

Suppression of microRNA-135b-5p protects against myocardial ischemia/reperfusion injury by activating JAK2/STAT3 signaling pathway in mice during sevoflurane anesthesia

The study aims to explore the effects of miR-135b-5p on myocardial ischemia/reperfusion (I/R) injuries by regulating Janus protein tyrosine kinase 2 (JAK2)/signal transducer and activator of transcription (STAT) signaling pathway by mediating inhalation anesthesia with sevoflurane. A sum of 120 healthy Wistar male mice was assigned into six groups. Left ventricular ejection fraction (LVEF) and left ventricular shortening fraction (LVSF) were detected. Cardiomyocyte apoptosis was determined by terminal dexynucleotidyl transferase mediated dUTP-biotin nick end labeling (TUNEL) assay. MiR-135b-5p expression, mRNA and protein expression of p-STAT3, p-JAK2, STAT3, JAK2, B-cell lymphoma-2 (Bcl-2) and Bcl-2 associated X protein B (Bax) were detected by quantitative real-time PCR (qRT-PCR) and Western blotting. Target relationship between miR-135b-5p and JAK2 was confirmed by dual-luciferase reporter assay. The other five groups exhibited increased cardiomyocyte necrosis, apoptosis, miR-135b-5p and Bax expression, mRNA expression of JAK2 and STAT3, and protein expression of p-STAT3 and p-JAK2 compared with the sham group, but showed decreased LVEF, LVFS, and Bcl-2 expression. Compared with the model and AG490 + Sevo groups, the Sevo, inhibitor + Sevo and inhibitor + AG490 + Sevo groups displayed reduced cardiomyocyte necrosis, apoptosis, miR-135b-5p and Bax expression, but displayed elevated mRNA expression of JAK2 and STAT3, protein expression of p-STAT3 and p-JAK2, LVEF, LVFS and Bcl-2 expression. Compared with the Sevo and inhibitor + AG490 + Sevo groups, the AG490 + Sevo group showed decreased LVEF, LVFS, Bcl-2 expression, mRNA expressions of JAK2 and STAT3, and protein expressions of p-STAT3 and p-JAK2, but increased cardiomyocyte necrosis, apoptosis, and Bax expressions. MiR-135b-5p negatively targetted JAK2. Inhibition of miR-135b-5p can protect against myocardial I/R injury by activating JAK2/STAT3 signaling pathway through mediation of inhalation anesthesia with sevoflurane.

Cobalt Chloride Upregulates Impaired HIF-1α Expression to Restore Sevoflurane Post-conditioning-Dependent Myocardial Protection in Diabetic Rats

Previous studies from our group have demonstrated that sevoflurane post-conditioning (SPC) protects against myocardial ischemia reperfusion injury via elevating the intranuclear expression of hypoxia inducible factor-1 alpha (HIF-1α). However, diabetic SPC is associated with decreased myocardial protection and disruption of the HIF-1 signaling pathway. Previous studies have demonstrated that cobalt chloride (CoCl₂) can upregulate HIF-1α expression under diabetic conditions, but whether myocardial protection by SPC can be restored afterward remains unclear. We established a rat model of type 2 diabetes and a Langendorff isolated heart model of ischemia-reperfusion injury. Prior to reperfusion, 2.4% sevoflurane was used as a post-conditioning treatment. The diabetic rats were treated with CoCl₂ 24 h before the experiment. At the end of reperfusion, tests were performed to assess myocardial function, infarct size, mitochondrial morphology, nitric oxide (NO), Mitochondrial reactive oxygen species (ROS), mitochondrial respiratory function and enzyme activity, HIF-1α, vascular endothelial growth factor (VEGF) and endothelial NO synthase (eNOS) protein levels. In addition, myocardial protection by SPC was monitored after the blood glucose levels were lowered by insulin. The diabetic state was associated with deficient SPC protection and decreased HIF-1α expression. After treating the diabetic rats with CoCl₂, SPC significantly upregulated the expression of HIF-1α, VEGF and eNOS, which markedly improved cardiac function, NO, mitochondrial respiratory function, and enzyme activity and decreased the infarction areas and ROS. In addition, these effects were not influenced by blood glucose levels. This study proved that CoCl₂activates the HIF-1α signaling pathway, which restores SPC-dependent myocardial protection under diabetic conditions, and the protective effects of SPC were independent of blood glucose levels.

Prostaglandin E2 reduces swine myocardial ischemia reperfusion injury via increased endothelial nitric oxide synthase and vascular endothelial growth factor expression levels

Prostaglandin E2 (PGE₂) has been demonstrated to attenuate cardiac ischemia-reperfusion (I/R) injury. However, the underlying mechanism of PGE₂ in cardiac I/R injury remains unknown. Upregulated expression levels of vascular endothelial growth factor (VEGF) and endothelial nitric oxide synthase (eNOS) were reported in acute myocardial infarction (AMI), and were demonstrated to diminish I/R injury. In the current study the involvement of VEGF and eNOS in the myocardial protective effect of PGE₂ were investigated in a catheter-based porcine model of AMI. Twenty-two Chinese miniature pigs were randomized into sham-surgery (n=6), control (n=8) and PGE₂ (n=8) groups. PGE₂ (1 µg/kg) was injected from 10 min prior to left anterior descending occlusion up to 1 h after reperfusion in the PGE₂ group. Subsequently, the hemodynamic parameters were evaluated. Thioflavin-S and Evans Blue double staining were performed to evaluate the extent of the myocardial reperfusion area (RA) and no-reflow area (NRA). Immunohistochemical and western blot analysis were used to evaluate protein expression levels of VEGF and eNOS. Left ventricular (LV) systolic pressure significantly improved and LV end-diastolic pressure significantly decreased in the PGE₂ group when compared with the control group 2 h after occlusion and 3 h after reperfusion (P<0.05, respectively). The RA and NRA were smaller in the PGE₂ group than in the control group (P<0.05, respectively). Furthermore, PGE₂ treatment increased the myocardial content of VEGF and eNOS when compared with the control group (P<0.05, respectively). Thus, the results of the present study demonstrate the cardio-protective mechanisms of PGE₂, which may protect the heart from I/R injury via enhancement of VEGF and eNOS expression levels.