Effect of HEMADO on Level of CK-MB and LDH Enzymes after Ischemia/Reperfusion Injury in Isolated Rat Heart

Mechanistic investigation of the ameliorative effect of liquiritin on hypoxia/reoxygenation‑induced cardiomyocyte injury based on network pharmacology and in vitro validation

Liquiritin (LIQ) is a flavonoid known for its cardioprotective properties, extracted from Glycyrrhiza uralensis Fisch. The purpose of the present study was to investigate the protective mechanism of LIQ against hypoxia/reoxygenation (H/R) injury through in vitro experiments, with the goal of enhancing its pharmacological effects. Initially, network pharmacology was employed to explore the targets and mechanisms of LIQ. Subsequently, an in vitro H/R model was established using H9c2 cells. Potential targets for LIQ and myocardial ischemia-reperfusion injury (MIRI) were identified through online databases. The STRING, Cytoscape and DAVID databases were used to extract intersecting targets and mechanisms. In vitro experiments were conducted to validate these findings, assessing cardiac enzymes, oxidative stress indicators, mitochondrial fluorescence, apoptotic fluorescence, inflammation and related protein expression. The network pharmacological analysis revealed that the protective effects of LIQ on MIRI involve oxidative stress, inflammation and apoptosis. The results of in vitro experimental validation demonstrated that LIQ significantly reduced the activities of lactated dehydrogenase and creatine kinase isoenzyme-MB (P<0.05 or 0.01), as well as the level of malondialdehyde (P<0.01). It also inhibited the production of reactive oxygen species (P<0.01), the release of inflammatory factors (P<0.05 or 0.01) and apoptosis (P<0.01). By contrast, the LIQ pre-treatment group exhibited a significant increase in mitochondrial membrane potential level (P<0.05 or 0.01) and the activities of antioxidant enzymes superoxide dismutase, catalase and glutathione peroxidase (P<0.05 or 0.01). Furthermore, LIQ reduced the protein expressions of TNF-α receptor type 1 (TNFR1) and MMP9, along with the level of NF-κB phosphorylation (P<0.05 or 0.01). In conclusion, LIQ mitigated H/R-induced cardiomyocyte injury through mechanisms that may involve antioxidants, anti-apoptotic effects, protection against mitochondrial damage and suppression of inflammatory levels. These effects are achieved via inhibition of the TNFR1/NF-κB/MMP9 pathway.

The promotion of sestrin2/AMPK signaling by HIF-1α overexpression enhances the damage caused by acute myocardial infarction

OBJECTIVE

Acute myocardial infarction (AMI), is a serious form of coronary heart disease. The present study sought to investigate the impact of HIF-1α on AMI, along with its fundamental mechanism.

METHODS

Sprague-Dawley (SD) rats were used to conduct an AMI model. 2,3,5-triphenyl-2H-tetrazolium chloride (TTC) staining was used examine the region of myocardial infract area at various time intervals. Protein expression levels were detected using western blotting. The rats were randomly divided into sham, model, negative control (NC), HIF-1α overexpression (HIF-1α-OE), and HIF-1α-OE+ si-sestrin2 groups. We examined the impact of HIF-1α overexpression on AMI rats using Haematoxylin-Eosin (H&E) staining, TTC staining, enzyme-linked immunosorbent assay (ELISA), TdT-mediated dUTP Nick-End Labeling (TUNEL) assay, and immunohistochemistry (IHC) staining.

RESULTS

According to the TTC findings, the region affected by myocardial infarction reached its peak at day 14. Based on the results from the western blot analysis, the levels of HIF-1α and sestrin2 were found the minimum on day 28. Subsequently, we discovered that the overexpression of HIF-1α rescued the cardiac function parameters, improved the morphology of myocardial tissue, and mitigated inflammation. Furthermore, the overexpression of HIF-1α led to a reduction in the levels of MDA and an increase in the levels of SOD. Moreover, the overexpression of HIF-1α resulted in a decrease in cellular apoptosis. This result was confirmed by the expression levels of Bcl-2 and Bax. Nevertheless, the defensive impact of elevated HIF-1α expression was somewhat counteracted by the suppression of sestrin2. In terms of mechanism, the overexpression of HIF-1α enhanced the levels of sestrin2 and the protein adenosine monophosphate activated kinase (AMPK).

CONCLUSION

Our research suggests that the overexpression of HIF-1α may rescue the damage to myocardial tissue, and this effect is associated with the sestrin2/AMPK signaling pathway. Our study provides a novel comprehension of the protective effects of HIF-1α overexpression on AMI.

Protective effects of safranal on hypoxia/reoxygenation-induced injury in H9c2 cardiac myoblasts via the PI3K/AKT/GSK3β signaling pathway

Safranal (SFR), an active ingredient extracted from saffron, exhibits a protective effect on the cardiovascular system. However, the mechanism of SFR against hypoxia/reoxygenation (H/R)-induced cardiomyocyte injury has previously not been investigated in vitro. The aim of the present study was therefore to observe the protective effects of SFR on H/R-induced cardiomyocyte injury and to explore its mechanisms. A H/R injury model of H9c2 cardiac myoblasts was established by administering 800 µmol/l CoCl₂ to H9c2 cells for 24 h and reoxygenating the cells for 4 h to induce hypoxia. H9c2 cardiac myoblasts were pretreated with SFR for 12 h to evaluate the associated protective effects. A Cell Counting Kit-8 assay was used for cell viability detection, and the expression levels of lactate dehydrogenase (LDH), creatine kinase-MB (CK-MB), glutathione peroxidase (GSH-px), catalase (CAT), superoxide dismutase (SOD), malondialdehyde (MDA) and caspase-3, and the intracellular Ca²⁺ concentration were measured using the corresponding commercial kits. Levels of reactive oxygen species (ROS) in the cells were detected using 2,7-dichlorodihydrofluorescein diacetate. Flow cytometry was used to determine the degree of apoptosis and the level of mitochondrial membrane potential (MMP). Moreover, the expression levels of phosphorylated (p-)PI3K, AKT, p-AKT, glycogen synthase kinase 3β (GSK3β), p-GSK3β, Bcl-2, Bax, caspase-3 and cleaved caspase-3 were measured using western blot analysis. Results of the present study demonstrated that the H9c2 cardiac myoblasts treated with SFR exhibited significantly improved levels of viability and significantly reduced levels of ROS, compared with the H/R group. Furthermore, compared with the H/R group, SFR treatment significantly increased the MMP levels and antioxidant enzyme levels, including CAT, SOD and GSH-px; whereas the levels of CK-MB, LDH, MDA and intracellular Ca²⁺ concentration were significantly decreased. Moreover, the results of the present study demonstrated that SFR significantly reduced caspase-3, cleaved caspase-3 and Bax protein expression levels, but upregulated the Bcl-2 protein expression levels. SFR also increased the protein expressions of PI3K/AKT/GSK3β. In summary, the results suggested that SFR may exert a protective effect against H/R-induced cardiomyocyte injury, which occurs in connection with the inhibition of oxidative stress and apoptosis via regulation of the PI3K/AKT/GSK3β signaling pathway.

Lycium barbarum polysaccharide protects rats and cardiomyocytes against ischemia/reperfusion injury via Nrf2 activation through autophagy inhibition

The irreversible loss of cardiomyocytes is mainly the result of ischemic/reperfusion (I/R) myocardial injury, leading to persistent heart dysfunction and heart failure. It has been reported that Lycium barbarum polysaccharide (LBP) has protective effects on cardiomyocytes, but the specific mechanism is still not completely understood. The present study examined the protective role of LBP in myocardial I/R injury. Rats were subjected to myocardial I/R injury and LBP treatment. Moreover, rat myocardial H9C2 cells exposed to hypoxia/reoxygenation (H/R) were used to simulate cardiac injury during myocardial I/R process and were exposed to LBP, rapamycin (an autophagy activator) or nuclear factor-erythroid factor 2-related factor 2 (Nrf2) transfection. Morphological examination, histopathological examination and echocardiography were used to determine the cardiac injury after I/R injury. Cell viability and apoptosis were determined via MTT and flow cytometry assays, respectively. The levels of lactate dehydrogenase (LDH), creatine kinase (CK), cardiac troponin T (cTnT), IL-1β, IL-6, TNF-α, malondialdehyde (MDA) and superoxidase dismutase (SOD) in rat serum, hearts and/or cells were assessed using ELISAs. The expression levels of Beclin 1, LC3II/LC3I, P62 and Nrf2 were analyzed via reverse transcription-quantitative PCR and western blotting. The results demonstrated that LBP improved heart function and repaired cardiomyocyte damage in I/R model rats, as well as reduced the production of cTnT, CK, LDH, IL-1β, IL-6 and TNF-α. The in vitro study results indicated that LBP increased cell viability, the apoptosis rate, and the levels of SOD and P62, as well as reduced the levels of LDH, CK, IL-1β, IL-6, TNF-α, MDA, Beclin 1 and LC3-II/LC3-I in H/R-injured H9C2 cells. Moreover, LBP promoted Nrf2 nuclear translocation, but decreased Nrf2 expression in the cytoplasm. Rapamycin exacerbated the aforementioned effects in H/R injured H9C2 cells, and partially reversed LBP-induced effects. Overexpressing Nrf2 counteracted I/R-induced effects and partially resisted rapamycin-induced effects. These findings demonstrated that LBP exhibited a cardiac protective effect on the ischemic myocardium of rats after reperfusion and attenuated myocardial I/R injury via autophagy inhibition-induced Nrf2 activation.

DL-3-n-butylphthalide protects H9c2 cardiomyoblasts from ischemia/reperfusion injury by regulating HSP70 expression via PI3K/AKT pathway activation

DL-3-n-butylphthalide (NBP) is commonly used to treat ischemic strokes due to its antioxidative and anti-inflammatory effects. The present study aimed to examine the protective effects of NBP on myocardial ischemia-reperfusion injury (MIRI) by establishing a MIRI model in H9c2 cells. Cell viability assay using Cell Counting Kit-8, lactate dehydrogenase (LDH) cytotoxicity and lipid peroxidation malondialdehyde (MDA) content were assessed to detect cell activity, degree of cell injury and oxidative stress reaction. Reverse transcription-quantitative PCR was used to quantify the expression of inflammatory factors in H9c2 cells. Western blotting and immunofluorescence staining were used to detect the protein expression of PI3K/AKT and heat shock protein 70 (HSP70). The present results indicated that NBP significantly increased cell viability during ischemia-reperfusion. Moreover, NBP inhibited the release of LDH and the production of MDA. NBP treatment also significantly decreased the expression of inflammatory factors at the mRNA level. Additionally, NBP activated the PI3K/AKT pathway and upregulated the expression of HSP70 compared with cells in the MIRI model. LY294002, a PI3K inhibitor, reversed the protective effects of NBP and suppressed the expression of HSP70. The present study demonstrated that NBP protected H9c2 cells from MIRI by regulating HSP70 expression via PI3K/AKT pathway activation.

MicroRNA-29b reduces myocardial ischemia-reperfusion injury in rats via down-regulating PTEN and activating the Akt/eNOS signaling pathway

Reperfusion may cause injuries to the myocardium in ischemia situation, which is called ischemia/reperfusion (I/R) injury. The study aimed to explore the roles of microRNA-29b (miR-29b) in myocardial I/R injury. Myocardial I/R injury rat model was established. Differentially expressed miRNAs between the model rats and the sham-operated rats were analyzed. miR-29b expression in myocardial tissues was measured. Gain-of-function of miR-29b was performed, and then the morphological changes, infarct size, myocardial function, oxidative stress, and the cell apoptosis in myocardial tissues were detected. The target relation between miR-29b and PTEN was detected through bio-information prediction and dual luciferase reporter gene assay. Activation of Akt/eNOS signaling was detected. H9C2 cells were subjected to hypoxia/reoxygenation treatment to perform in vitro experiments. I/R rats presented severe inflammatory infiltration, increased infarct size and cell apoptosis, increased oxidative stress and decreased myocardial function. miR-29b was downregulated in I/R rats, and up-regulation of miR-29b reversed the above changes. miR-29b directly bound to PTEN, and overexpression of miR-29b reduced PTEN expression level and increased the protein levels of p-Akt/Akt and p-eNOS/eNOS. In vivo results were confirmed in in vitro experiments. This study provided evidence that miR-29b could alleviate the myocardial I/R injury in vivo and in vitro by inhibiting PTEN expression and activating the Akt/eNOS signaling pathway.

Hydrogen sulfide restores cardioprotective effects of remote ischemic preconditioning in aged rats via HIF-1α/Nrf2 signaling pathway

The present study explored the therapeutic potential of hydrogen sulfide (H₂S) in restoring aging-induced loss of cardioprotective effect of remote ischemic preconditioning (RIPC) along with the involvement of signaling pathways. The left hind limb was subjected to four short cycles of ischemia and reperfusion (IR) in young and aged male rats to induce RIPC. The hearts were subjected to IR injury on the Langendorff apparatus after 24 h of RIPC. The measurement of lactate dehydrogenase, creatine kinase and cardiac troponin served to assess the myocardial injury. The levels of H₂S, cystathionine β-synthase (CBS), cystathionine γ-lyase (CSE), nuclear factor erythroid 2-related factor 2 (Nrf2), and hypoxia-inducible factor (HIF-1α) were also measured. There was a decrease in cardioprotection in RIPC-subjected old rats in comparison to young rats along with a reduction in the myocardial levels of H₂S, CBS, CSE, HIF-1α, and nuclear: cytoplasmic Nrf2 ratio. Supplementation with sodium hydrogen sulfide (NaHS, an H₂S donor) and l-cysteine (H₂S precursor) restored the cardioprotective actions of RIPC in old hearts. It increased the levels of H₂S, HIF-1α, and Nrf2 ratio without affecting CBS and CSE. YC-1 (HIF-1α antagonist) abolished the effects of NaHS and l-cysteine in RIPC-subjected old rats by decreasing the Nrf2 ratio and HIF-1α levels, without altering H₂S.The late phase of cardioprotection of RIPC involves an increase in the activity of H₂S biosynthetic enzymes, which increases the levels of H₂S to upregulate HIF-1α and Nrf2. H₂S has the potential to restore aging-induced loss of cardioprotective effects of RIPC by upregulating HIF-1α/Nrf2 signaling.

Temperature-sensitive bone mesenchymal stem cells combined with mild hypothermia reduces neurological deficit in rats of severe traumatic brain injury

BACKGROUND

To explore the combined influences of temperature-sensitive bone mesenchymal stem cells (tsBMSCs) and mild hypothermia (MH) on neurological function and glucose metabolism in rats with severe traumatic brain injury (TBI).

METHODS

SD rats were randomly divided into sham, TBI, TBI + MH, TBI + BMSCs and TBI + MH +tsBMSCs groups. Then, the brain water content, serum-specific proteins (S100β, NSE, LDH, and CK), and blood glucose at different time points were measured. Furthermore, GLUT-3 expression was detected by Western blotting, and apoptotic rate was determined by TUNEL staining.

RESULTS

After TBI rat establishment, the brain injury resulted in significant increases in mNSS scores and brain water content, and upregulations in serum levels of S100β, NSE, LDH and CK, and blood glucose, with the elevated cell apoptotic rate in the injured cortex. However, these changes were reversed by MH alone, BMSCs alone, or combination treatment of MH and tsBMSCs in varying degrees, and the combination treatment was superior to the treatment with BMSCs or MH alone.

CONCLUSION

Combination therapy of tsBMSCs and MH can reduce the neuronal apoptosis in severe TBI rats, with the suppression of serum biomarkers and hyperglycemia, contributing to the recovery of neurological functions.

ABBREVIATIONS

tsBMSCs: temperature-sensitive bone mesenchymal stem cells; MH: mild hypothermia; TBI: traumatic brain injury; mNSS: modified Neurological Severity Score.

Rosuvastatin Attenuates Myocardial Ischemia-Reperfusion Injury via Upregulating miR-17-3p-Mediated Autophagy

Myocardial diseases usually appear ischemic. Reperfusion therapy is one of the effective methods that can improve clinical therapeutic efficacy. However, reperfusion results in myocardial injury named I/R injury. Rosuvastatin (RS) is HMG-CoA reductase inhibitor. We investigated the role of RS in the myocardial I/R injury in vitro and its active mechanism. Oxygen-glucose deprivation/reoxygenation (OGD/R) model was applied to investigate I/R in vitro. OGD/R decreased cell viability and increased levels of miR-17-3p and lactate dehydrogenase (LDH) leakage. Besides, RS decreased cleaved caspase-3 level and LDH leakage, promoted the levels of miR-17-3p and LC3II/LC3I, and increased cell viability when H9C2 cell was treated by OGD/R. miR-17-3p inhibitor reduced the H9C2 cell viability and LC3II/LC3I level, whereas miR-17-3p mimics increased H9C2 cell viability and LC3II/LC3I level. RS promoted cell viability and increased LC3II/LC3I level while it lowered LDH leakage, apoptosis rate, and the levels of cleaved caspase-3 and Cyto c. Our study suggested that RS reduced I/R injury in cardiocyte via cleaved caspase-3/Cyto c apoptosis signaling pathway and autophagy. Moreover, the autophagy happens to cardiocyte by upregulating the expression of miR-17-3p.

Puerarin inhibits apoptosis and inflammation in myocardial cells via PPARα expression in rats with chronic heart failure

Chronic heart failure affects myocardial energy metabolism and cardiac function. Puerarin has been reported to improve cardiac function through regulation of energy metabolism in mice with myocardial infarction. The aim of the current study was to determine whether puerarin can improve body weight and reduce inflammation and apoptosis in rats with chronic heart failure. Rats were divided into three groups: Puerarin, PBS and sham group. Transverse aortic constriction was performed to induce chronic heart failure in the puerarin an PBS groups. Cardiac function, apoptosis and inflammation were evaluated following a 4-week treatment in rats with chronic heart failure. The results demonstrated that puerarin significantly increased the survival rate of rats and improved cardiac function compared with the PBS group. In addition, puerarin decreased lactate dehydrogenase and succinate dehydrogenase activity compared with the PBS group. Puerarin treatment increased the expression levels of glucose transporter type 4 and decreased the expression levels of CD36. Additionally, puerarin decreased the levels inflammatory factors, including tumor necrosis factor α, interleukin (IL)-1β and IL-6 in serum and myocardial tissue compared with the PBS group. Puerarin upregulated peroxisome proliferator-activated receptor α (PPARα) and its downstream target genes nuclear respiratory factor 1, FOS proto-oncogene, YY1 transcription factor, acetyl-coenzyme A carboxylase a, Fas cell surface death receptor, L-type pyruvate kinase and acetyl-coenzyme A dehydrogenase medium chain in myocardial cells from rats with chronic heart failure. These results demonstrated that puerarin inhibited apoptosis and inflammation in myocardial cells via the PPARα pathway. In conclusion, the present study indicated that puerarin may exhibit antiapoptotic and anti-inflammatory activity through the PPARα pathway in rats with chronic heart failure.

Phloroglucinol, a nutraceutical for IR-induced cardiac damage in diabetic rats

BACKGROUND

Myocardial injury due to ischemia-reperfusion (IR) is aggravated in diabetes which is associated with oxidative stress. Alleviating oxidative stress via use of antioxidants has been shown to be effective at minimizing myocardial cell death and improving cardiac function. The aim of the present study was to evaluate the cardioprotective effect of phloroglucinol against myocardial reperfusion injury (MRI) in diabetic rats.

METHODS

Diabetes was induced in female rats with streptozotocin (50 mg/kg). The diabetic rats were orally treated with phloroglucinol (100 and 200 mg/kg daily for 28 days). After treatment the hearts were isolated and mounted on a Langendorff apparatus. The hearts were subjected to 15 minutes of IR to induce myocardial damage. Cardiac functions including heart rate (HR), resting and developed tension, and rate of change of contraction (+dP/dt max) were recorded. Cardiac injury biomarkers lactate dehydrogenase (LDH) and creatine kinase (CK-MB) were measured in the heart perfusate. Levels of the antioxidant enzymes reduced glutathione (GSH) and malondialdehyde (MDA) were measured. Hematoxylin and eosin (H&E) staining was also performed.

RESULTS

After IR injury, a decrease in HR and +dP/dt max in hearts from diabetic rat was seen compared to healthy rat hearts, which was reversed by phloroglucinol treatment. Myocardial infarct size, measured by H&E staining, was increased in diabetic rats compared to healthy rats and an increase in the activity of LDH and CK-MB in the heart perfusate in diabetic rats was decreased by phloroglucinol treatment. An increase in MDA levels and a decrease in levels of antioxidant enzymes were observed in diabetic rats, which was reversed with phloroglucinol treatment.

CONCLUSION

Phloroglucinol treatment has potential therapeutic promise in the treatment of MRI in diabetes.

Protective Effects of Baicalin on Experimental Myocardial Infarction in Rats

Objective

This study aimed to investigate the protective effects of baicalin on myocardial infarction in rats and explore the related mechanisms.

Methods

Fifty Sprague Dawley rats were randomly divided into the control, model, and low-, medium- and high-dose baicalin groups. The latter 3 groups were intraperitoneally injected with baicalin, with a dose of 12.5, 25 and 50 mg/kg, respectively. Then, the myocardial infarction model was established. The hemodynamic of rats was tested, the serum lactate dehydrogenase (LDH), creatine kinase-MB (CK-MB), prostacyclin (PGI₂) and thromboxane A₂ (TXA₂) were determined, the myocardial superoxide dismutase (SOD) and malondialdehyde (MDA) levels were detected, and the myocardial B-cell lymphoma-2 (Bcl-2) and Bcl-2 associated X (Bax) protein expressions were determined.

Results

Compared with the model group, in the high-dose baicalin group the ST segment height and LVEDP were significantly decreased (P<0.05), the LVSP was significantly increased (P<0.05), the serum LDH, CK-MB and TXA2 levels were significantly decreased (P<0.05), the PGI₂ level was significantly increased (P<0.05), the myocardial SOD level was significantly increased (P<0.05), and the myocardial MDA level was significantly decreased (P<0.05); the myocardial Bcl-2 protein level was significantly increased, and the Bax protein level was significantly decreased (P<0.05).

Conclusion

Baicalin has protective effects on myocardial infarction in rats. The possible mechanisms may be related to its resistance to oxidative stress, and up-regulation of Bcl-2 protein expression and down-regulation of Bax protein expression in myocardial tissue.

BYD Ameliorates Oxidative Stress-Induced Myocardial Apoptosis in Heart Failure Post-Acute Myocardial Infarction via the P38 MAPK-CRYAB Signaling Pathway

Aim: Heart failure (HF) post-acute myocardial infarction (AMI) contributes to increasing mortality and morbidity worldwide. Baoyuan decoction (BYD) is a well-known traditional Chinese medicine formula that exhibits myocardial protection clinically. The aim of this study was to identify the effects of BYD on oxidative stress-induced apoptosis in HF post-AMI and characterize the underlying mechanism.

Methods and Results: In our study, we constructed left anterior descending (LAD)-induced AMI rat models and a macrophage-conditioned media (CM)-induced H9C2 injury model. In vivo, BYD could protect cardiac functions, decrease inflammatory cell infiltration and inhibit oxidative stress-induced apoptosis. In vitro, BYD inhibited cellular apoptosis and regulated the expressions of key apoptotic molecules, including reducing the expression of B cell lymphoma-2 (Bcl-2) associated X protein (Bax) and cleaved caspase-3 and -9. Interestingly, the P38 mitogen-activated protein kinase (MAPK)-αB-crystallin (CRYAB) signaling pathway was activated by BYD treatment, and the P38 MAPK inhibitor SB203580 could reverse the protective effects of BYD.

Conclusion: This study identified that BYD protected against oxidative stress-induced myocardial apoptosis via the P38 MAPK-CRYAB pathway. CRYAB may become a novel therapeutic target for AMI.

[Establishment of an ex vivo myocardial ischemia-reperfusion model in tree shrews]

OBJECTIVE

To establish an ex vivo model of myocardial ischemia reperfusion in tree shrews.

METHODS

The Langendorff ex vivo heart perfusion system was used to establish the myocardial ischemia reperfusion model in tree shrews with different irrigation and reperfusion time settings. Alanine aminotransferase (ALT), aspartate transaminase (AST) and lactic dehydrogenase (LDH) levels were measured by enzyme-labeled immunosorbent assay, creatine kinase MB (CK-MB) was detected using immunosuppression method, and malondialdehyde was measured with thiobarbital staining method; the infarct size was measured using 2, 3, 5-triphenyltrazoliumchloride (TTC) method.

RESULTS

Ischemia for 30 min and reperfusion for 30 and 60 min caused more significant increase in CK-MB and LDH levels in the perfusion fluid and also in the levels of ALT, CK-MB and AST in the myocardial tissue compared with other experimental settings (P<0.05), but these parameters were comparable between the former two settings (P>0.05). The mean heart rate in 30-min ischemia with 60-min reperfusion group was obviously lower than that in continuous reperfusion group, 15-min ischemia with 30-min reperfusion group and 30-min ischemia with 30-min reperfusion group (P<0.05), and the heart rate was similar between the latter 3 groups (P>0.05). ECG analysis showed that the mean heart rate in 30-min ischemia with 30-min reperfusion group was closer to the physiological heart rate of tree shrews.

CONCLUSION

We successfully established an ex vivo myocardial ischemia reperfusion model using tree shrews, and ischemia for 30 min followed by reperfusion for 30 min is the optimal experimental setting.

[Establishment of an ex vivo myocardial ischemia-reperfusion model in tree shrews]

OBJECTIVE

To establish an ex vivo model of myocardial ischemia reperfusion in tree shrews.

METHODS

The Langendorff ex vivo heart perfusion system was used to establish the myocardial ischemia reperfusion model in tree shrews with different irrigation and reperfusion time settings. Alanine aminotransferase (ALT), aspartate transaminase (AST) and lactic dehydrogenase (LDH) levels were measured by enzyme-labeled immunosorbent assay, creatine kinase MB (CK-MB) was detected using immunosuppression method, and malondialdehyde was measured with thiobarbital staining method; the infarct size was measured using 2, 3, 5-triphenyltrazoliumchloride (TTC) method.

RESULTS

Ischemia for 30 min and reperfusion for 30 and 60 min caused more significant increase in CK-MB and LDH levels in the perfusion fluid and also in the levels of ALT, CK-MB and AST in the myocardial tissue compared with other experimental settings (P<0.05), but these parameters were comparable between the former two settings (P>0.05). The mean heart rate in 30-min ischemia with 60-min reperfusion group was obviously lower than that in continuous reperfusion group, 15-min ischemia with 30-min reperfusion group and 30-min ischemia with 30-min reperfusion group (P<0.05), and the heart rate was similar between the latter 3 groups (P>0.05). ECG analysis showed that the mean heart rate in 30-min ischemia with 30-min reperfusion group was closer to the physiological heart rate of tree shrews.

CONCLUSION

We successfully established an ex vivo myocardial ischemia reperfusion model using tree shrews, and ischemia for 30 min followed by reperfusion for 30 min is the optimal experimental setting.

The cardioprotection of dihydrotanshinone I against myocardial ischemia–reperfusion injury via inhibition of arachidonic acid ω-hydroxylase

Arachidonic acid (AA) is a precursor that is metabolized by several enzymes to many biological eicosanoids. Accumulating data indicate that the ω-hydroxylation metabolite of AA, 20-hydroxyeicosatetraenoic acid (20-HETE), is considered to be involved in the myocardial ischemia–reperfusion injury (MIRI). The inhibitors of AA ω-hydroxylase, however, are demonstrated to exhibit protective effects on MIRI. Dihydrotanshinone I (DI), a bioactive constituent of danshen, is proven to be a potent inhibitor of AA ω-hydroxylase by our preliminary study in vitro. The purpose of the present study was to investigate the cardioprotection of DI against MIRI and its effects on the concentrations of 20-HETE in vivo. Rats subjected to 30 min of ischemia followed by 24 h of reperfusion were assigned to intravenously receive vehicle (sham and ischemia–reperfusion), low (1 mg/kg), middle (2 mg/kg), or high (4 mg/kg) doses of DI before reperfusion. The results demonstrated that DI treatment could improve cardiac function, reduce infarct size, ameliorate the variations in myocardial zymogram and histopathological disorders, decrease 20-HETE generation, and regulate apoptosis-related protein in myocardial ischemia–reperfusion rats. These findings suggested DI could exert considerable cardioprotective action on MIRI by the attenuation of 20-HETE generation, subsequent myocardial injury, and apoptosis through inhibition on AA ω-hydroxylase.

A Novel Method for Evaluating the Cardiotoxicity of Traditional Chinese Medicine Compatibility by Using Support Vector Machine Model Combined with Metabonomics

Traditional biochemical and histopathological tests have been used to evaluate the safety of traditional Chinese medicine (TCM) compatibility for a long time. But these methods lack high sensitivity and specificity. In the previous study, we have found ten biomarkers related to cardiotoxicity and established a support vector machine (SVM) prediction model. Results showed a good sensitivity and specificity. Therefore, in this study, we used SVM model combined with metabonomics UPLC/Q-TOF-MS technology to build a rapid and sensitivity and specificity method to predict the cardiotoxicity of TCM compatibility. This study firstly applied SVM model to the prediction of cardiotoxicity in TCM compatibility containing Aconiti Lateralis Radix Praeparata and further identified whether the cardiotoxicity increased after Aconiti Lateralis Radix Praeparata combined with other TCM. This study provides a new idea for studying the evaluation of the cardiotoxicity caused by compatibility of TCM.

In vitro evaluation of aspirin-induced HspB1 against heat stress damage in chicken myocardial cells

To understand the potential association of heat stress resistance with HspB1 induction by aspirin (ASA) in chicken myocardial cells, variations of HspB1 expression and heat stressed-induced damage of myocardial cells after ASA administration were studied in primary cultured myocardial cells. Cytopathological lesions as well as damage-related enzymes, such as creatine kinase-MB (CK-MB) and lactate dehydrogenase (LDH), indicated the considerable protective ability of ASA pre-treatment against acute heat stress. Immunostaining assays showed that heat stress caused HspB1 to relocate into the nucleus, while ASA did not. ELISA analysis, revealed that HspB1 expression induced by ASA averaged 45.62-fold higher than that of the control. These results indicated that the acute heat-stressed injuries were accompanied by comparatively lower HspB1 expression caused by heat stress in vitro. ASA pre-treatment induced a level of HspB1 presumed to be sufficient to protect myocardial cells from acute heat stress in the extracorporal model, although more detailed mechanisms will require further investigation.

The Effect of Sleep Deprivation on Cardiac Function and Tolerance to Ischemia-Reperfusion Injury in Male Rats

BACKGROUND

Sleep deprivation (SD) is strongly associated with elevated risk for cardiovascular disease.

OBJECTIVE

To determine the effect of SD on basal hemodynamic functions and tolerance to myocardial ischemia-reperfusion (IR) injury in male rats.

METHOD

SD was induced by using the flowerpot method for 4 days. Isolated hearts were perfused with Langendorff setup, and the following parameters were measured at baseline and after IR: left ventricular developed pressure (LVDP); heart rate (HR); and the maximum rate of increase and decrease of left ventricular pressure (± dp/dt). Heart NOx level, infarct size and coronary flow CK-MB and LDH were measured after IR. Systolic blood pressure (SBP) was measured at start and end of study.

RESULTS

In the SD group, the baseline levels of LVDP (19%), +dp/dt (18%), and -dp/dt (21%) were significantly (p < 0.05) lower, and HR (32%) was significantly higher compared to the controls. After ischemia, hearts from SD group displayed a significant increase in HR together with a low hemodynamic function recovery compared to the controls. In the SD group, NOx level in heart, coronary flow CK-MB and LDH and infarct size significantly increased after IR; also SD rats had higher SBP after 4 days.

CONCLUSION

Hearts from SD rats had lower basal cardiac function and less tolerance to IR injury, which may be linked to an increase in NO production following IR.

Moutan cortex extract exerts protective effects in a rat model of cardiac ischemia/reperfusion

Moutan cortex (MC) is a traditional Chinese medicine with diverse biological effects. The present study was performed to investigate the effects of MC on myocardial ischemia/reperfusion (I/R) in rats and to explore its possible mechanisms. Sprague-Dawley rats were administered MC extract (1.98 g/kg, i.g.) for 14 days and underwent a subsequent open-chest procedure involving 30 min of myocardial ischemia and 60 min of reperfusion. The cardioprotective effect of MC was demonstrated by reduced infarct size and marked improvement in the histopathological examination. The increase in the activity of superoxide dismutase (SOD) and glutathione (GSH) as well as the reduction of malondialdehyde (MDA) indicated that MC effectively promoted the anti-oxidative defense system. Increased anti-oxidative defense was accompanied by decreased release of lactate dehydrogenase (LDH) and creatine kinase (CK). The reduction in TUNEL-positive myocytes demonstrated that MC decreased myocardial apoptosis. The mRNA expression of B cell leukemia-2 (Bcl-2) was upregulated by MC and the ratio of Bcl-2/Bcl-2-associated X protein (Bax) mRNA expression was increased. MC pretreatment decreased the mRNA expression of inducible nitric oxide synthase (iNOS). The data from this study suggest that MC exerted protective effects on acute myocardial I/R injury via anti-oxidative and anti-apoptotic activities.

Acetyl salicylic acid protected against heat stress damage in chicken myocardial cells and may associate with induced Hsp27 expression

We investigated whether acetyl salicylic acid (ASA) protects chicken myocardial cells from heat stress-mediated damage in vivo and whether the induction of Hsp27 expression is connected with this function. Pathological changes, damage-related enzyme levels, and Hsp27 expression were studied in chickens following heat stress (40 ± 1 °C for 0, 1, 2, 3, 5, 7, 10, 15, or 24 h, respectively) with or without ASA administration (1 mg/kg BW, 2 h prior). Appearance of pathological lesions such as degenerations and karyopyknosis as well as the myocardial damage-related enzyme activation indicated that heat stress causes considerable injury to the myocardial cells in vivo. Myocardial cell injury was most serious in chickens exposed to heat stress without prior ASA administration; meanwhile, ASA pretreatment acted protective function against high temperature-induced injury. Hsp27 expression was induced under all experimental conditions but was one-fold higher in the ASA-pretreated animals (0.3138 ± 0.0340 ng/mL) than in untreated animals (0.1437 ± 0.0476 ng/mL) 1 h after heat stress exposure, and such an increase was sustained over the length of the experiment. Our findings indicate that pretreatment with ASA protects chicken myocardial cells from acute heat stress in vivo with almost no obvious side effects, and this protection may involve an enhancement of Hsp27 expression. However, the detailed mechanisms underlying this effect require further investigation.