• The Korean Journal of Physiology and Pharmacology
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• v.23 no.1
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• pp.37-45
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• 2019

To study the effect of nicorandil pretreatment on ketone body metabolism and Acetyl-CoA acetyltransferase (ACAT1) activity in hypoxia/reoxygenation (H/R)-induced cardiomyocytes. In our study, we applied H9c2 cardiomyocytes cell line to evaluate the cardioprotective effects of nicorandil. We detected mitochondrial viability, cellular apoptosis, reactive oxygen species (ROS) production and calcium overloading in H9c2 cells that exposed to H/R-induced cytotoxicity. Then we evaluated whether nicorandil possibly regulated ketone body, mainly ${\beta}$-hydroxybutyrate (BHB) and acetoacetate (ACAC), metabolism by regulating ACAT1 and Succinyl-CoA:3-ketoacid coenzyme A transferase 1 (OXCT1) protein and gene expressions. Nicorandil protected H9c2 cardiomyocytes against H/R-induced cytotoxicity dose-dependently by mitochondria-mediated anti-apoptosis pathway. Nicorandil significantly decreased cellular apoptotic rate and enhanced the ratio of Bcl-2/Bax expressions. Further, nicorandil decreased the production of ROS and alleviated calcium overloading in H/R-induced H9c2 cells. In crucial, nicorandil upregulated ACAT1 and OXCT1 protein expressions and either of their gene expressions, contributing to increased production of cellular BHB and ACAC. Nicorandil alleviated cardiomyocytes H/R-induced cytotoxicity through upregulating ACAT1/OXCT1 activity and ketone body metabolism, which might be a potential mechanism for emerging study of nicorandil and other $K_{ATP}$ channel openers.

• The Korean Journal of Physiology and Pharmacology
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• v.19 no.3
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• pp.203-210
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• 2015

AMP-activated protein kinase (AMPK) is a key regulator of energy metabolism. Previous studies have shown that activation of AMPK results in suppression of cardiac myocyte hypertrophy via inhibition of the p70S6 kinase (p70S6K) and eukaryotic elongation factor-2 (eEF2) signaling pathways. Epigallocatechin-3-gallate (EGCG), the major polyphenol found in green tea, possesses multiple protective effects on the cardiovascular system including cardiac hypertrophy. However, the molecular mechanisms has not been well investigated. In this study, we found that EGCG could significantly reduce natriuretic peptides type A (Nppa), brain natriuretic polypeptide (BNP) mRNA expression and decrease cell surface area in H9C2 cardiomyocytes stimulated with phenylephrine (PE). Moreover, we showed that AMPK is activated in H9C2 cardiomyocytes by EGCG, and AMPK-dependent pathway participates in the inhibitory effects of EGCG on cardiac hypertrophy. Taken together, our findings provide the first evidence that the effect of EGCG against cardiac hypertrophy may be attributed to its activation on AMPK-dependent signaling pathway, suggesting the therapeutic potential of EGCG on the prevention of cardiac remodeling in patients with pressure overload hypertrophy.

• Environmental Analysis Health and Toxicology
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• v.27
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• pp.11.1-11.8
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• 2012

Objectives: Hepatotoxicity of acetaminophen has been widely studied. However, the adverse effects on the heart have not been sufficiently evaluated. This study was performed to investigate cytotoxicity and alterations of gene expression in cultured cardiomyocytes ($H_9C_2$ cells) after exposure to acetaminophen. Methods: $H_9C_2$ cells were incubated in a 10 mM concentration of acetaminophen for the designated times (6, 12, and 24 hours), and cytotoxicity was determined by the 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method. Alteration of gene expression was observed by microarray analysis, and RT-PCR was performed for the three representative oxidative stress-related genes at 24 hours after treatment. Results: It revealed that acetaminophen was toxic to cardiomyocytes, and numerous critical genes were affected. Induced genes included those associated with oxidative stress, DNA damage, and apoptosis. Repressed genes included those associated with cell proliferation, myocardial contraction, and cell shape control. Conclusions: These findings provide the evidences of acetaminophen-induced cytotoxicity and changes in gene expression in cultured cardiomyocytes of $H_9C_2$ cells.

• YAKHAK HOEJI
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• v.52 no.3
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• pp.212-218
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• 2008

Manganese is a naturally occurring element which is widespread in the environment. Also, manganese is an essential trace element and plays a key role in important biological reactions catalyzed by enzymes. However, exposure to high levels of manganese can cause toxicity in neurone and inhalation system, also damage in various tissues. We investigated the toxicity induced by manganese compound ($MnCl_2$) in cultured rat cardiomyocytes. Treatment of manganese to cultured cardiomyocyte led to cell death, reactive oxygen species (ROS) increase, and cytosolic caspase-3 activation. The ROS increase was related with the decreased level of glutathione. Expressions of ROS related genes such as heme oxygenase-1, thioredoxin reductase, and NADH quinone oxidase were significantly induced in manganese treated cells. These results suggest that manganese induce oxidative stress and apoptosis in cardiomyocytes, and may be the one of risk factors to cause heart dysfunction in vivo.

• Proceedings of the Korean Society of Toxicology Conference
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• 2005.05a
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• pp.203-203
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• 2005

• Bulletin of the Korean Chemical Society
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• v.30 no.4
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• pp.897-901
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• 2009

Heme oxygenase-1 (HO-1) is an anti-inflammatory and anti-apoptotic protein and has been applied to various gene therapy researches. However, constitutive expression of HO-1 may induce deleterious side effects. In this research, hypoxia inducible HO-1 expression plasmid, pEpo-SV-HO-1, was constructed with the erythropoietin (epo) enhancer and simian virus 40 (SV40) promoter to avoid these unwanted side effects. Dexamethasone conjugated polyethylenimine (PEI-Dexa) was used as a gene carrier. It was previously reported that dexamethasone protected cardiomyocytes from apoptosis under hypoxia. In this research, PEI-Dexa reduced the caspase-3 level in hypoxic H9C2 cardiomyocytes as a derivative of dexamethasone, suggesting that PEI-Dexa is an anti-apoptotic reagent as well as a gene carrier. pEpo-SV-HO-1 was transfected to H9C2 cardiomyocytes using PEI-Dexa and the cells were incubated under normoxia or hypoxia. HO-1 expression was induced in the pEpo-SV-HO-1 transfected cells under hypoxia. In addition, cell viability under hypoxia was higher in the pEpo-SV-HO-1 transfected cells than the pEpo-SV-Luc transfected cells. Also, caspase-3 level was reduced in the pEpo-SV-HO-1 transfected cells under hypoxia. In addition to the anti-apoptotic effect of PEI-Dexa, hypoxia inducible HO-1 expression by pEpo-SVHO- 1 may be helpful to protect cardiomyocytes under hypoxia. Therefore, pEpo-SV-HO-1/PEI-Dexa complex may be useful for ischemic heart disease gene therapy.

• The Korean Journal of Physiology and Pharmacology
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• v.26 no.5
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• pp.325-333
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• 2022

Heart failure (HF) has become one of the severe public health problems. The detailed role of mitochondrial function in HF was still unclear. Benzoylaconine (BAC) is a traditional Chinese medicine, but its role in HF still needs to be explored. In this study, oxygen-glucose deprivation and reperfusion (OGD/R) was executed to mimic the injury of H9C2 cells in HF. The viability of H9C2 cells was assessed via MTT assay. OGD/R treatment markedly decreased the viability of H9C2 cells, but BAC treatment evidently increased the viability of OGD/R-treated H9C2 cells. The apoptosis of H9C2 was enhanced by OGD/R treatment but suppressed by BAC treatment. The mitochondrial membrane potential was evaluated via JC-1 assay. BAC improved the mitochondrial function and suppressed oxidative stress in OGD/R-treated H9C2 cells. Moreover, Western blot analysis revealed that the protein expression of p-AMPK and PGC-1α were reduced in OGD/R-treated H9C2 cells, which was reversed by BAC. Rescue assays indicated that AMPK attenuation reversed the BAC-mediated protective effect on OGD/R-treated cardiomyocytes. Moreover, BAC alleviated myocardial injury in vivo. In a word, BAC modulated the mitochondrial function in OGD/R-induced cardiomyocyte injury by activation of the AMPK/PGC-1 axis. The findings might provide support for the application of BAC in the treatment of HF.

• The Korean Journal of Physiology and Pharmacology
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• v.9 no.4
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• pp.195-201
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• 2005

High extracellular glucose concentration was reported to suppress intracellular $Ca^{2+}$ clearing through altered sarcoplasmic reticulum (SR) function. In the present study, we attempted to elucidate the effects of pyruvate and fatty acid on SR function and reveal the mechanistic link with glucose-induced SR dysfunction. For this purpose, SR $Ca^{2+}$-uptake rate was measured in digitonin-permeabilized H9c2 cardiomyocytes cultured in various conditions. Exposure of these cells to 5 mM pyruvate for 2 days induced a significant suppression of SR $Ca^{2+}$-uptake, which was comparable to the effects of high glucose. These effects were accompanied with decreased glucose utilization. However, pyruvate could not further suppress SR $Ca^{2+}$-uptake in cells cultured in high glucose condition. Enhanced entry of pyruvate into mitochondria by dichloroacetate, an activator of pyruvate dehydrogenase complex, also induced suppression of SR $Ca^{2+}$-uptake, indicating that mitochondrial uptake of pyruvate is required in the SR dysfunction induced by pyruvate or glucose. On the other hand, augmentation of fatty acid supply by adding 0.2 to 0.8 mM oleic acid resulted in a dose-dependent suppression of SR $Ca^{2+}$-uptake. However, these effects were attenuated in high glucose-cultured cells, with no significant changes by oleic acid concentrations lower than 0.4 mM. These results demonstrate that (1) increased pyruvate oxidation is the key mechanism in the SR dysfunction observed in high glucose-cultured cardiomyocytes; (2) exogenous fatty acid also suppresses SR $Ca^{2+}$-uptake, presumably through a mechanism shared by glucose.

• Journal of Physiology & Pathology in Korean Medicine
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• v.21 no.4
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• pp.1010-1016
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• 2007

Sagunjatang (Sagunja), containing Radix Astragali, Radix Ginseng, Fructus Schizandrae, Radix Ophiopogonis and Radix Glycyrrhizae, has been used as a prescription for ischemic heart and brain diseases in Korean traditional medicine. This study was designed to investigate the protective mechanisms of Sagunja on $H_2O_2$-induced cytotoxicity of H9c2 cardiomyocytes. Treatment with $H_2O_2$ resulted in death of H9c2 cells, characterized by apparent apoptotic features, including the fragmentation of nucleus and increase in sub-GO/G1fraction of cell cycle. However, Sagunja markedly suppressed the apoptotic characteristics of H9c2 cells induced by $H_2O_2$ with decrease of intracellular peroxide level. In addition, Sagunja suppressed the features of mitochondrial dysfunction, including change of mitochondrial membrane potential, in $H_2O_2$- treated cells. Additionally, Sagunja induced the expression of HO-1 protein in both time-and dose-dependent manner. The role of HO-1 in ROS-scavenging activity of Sagunja is proposed.

• Environmental Analysis Health and Toxicology
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• v.21 no.1 s.52
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• pp.71-79
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• 2006

Epidemiologic studies have showed a close correlation between arsenic exposure and heart disease such as, cardiovascular problem, ischemic heart disease, infarction, atherosclerosis and hypertension in human. It may increase the mortality of high risk group with heart disease. Regarding the mechanism studies of heart failure, blood vessel, vascular smooth muscle cells and endothelial cells have long been focused as the primary targets in arsenic exposure but there are only a few studies on the cardiomyocytes. In this study, the generation of oxidative stress by low dose of arsenic trioxide was investigated in rat cardiomyocytes. By direct measurement of reactive oxygen species and fluorescent microscopic observation using fluorescent dye 2',7'-dichlorofluorescin diacetate, reactive oxygen species were found to be generated without cell death, where cells are treated with 0.1 ppm arsenic for 24 hours. With the induction of reactive oxygen species, GSH level was decreased by the same treatment. However, DNA damage did not seem to be serious by DAPI staining, while high dose of arsenic (2 ppm for 24 hrs) caused fragmentation of DNA. To identify the molecular biomarkers of low-dose arsenic exposure, gene expression was also investigated with whole genome microarray. As results, 9,022 genes were up-regulated including heme oxygenase-l and glutathione S-transrerase, which are well-known biomarkers of oxidative stress. 9,404 genes were down-regulated including endothelial type gp 91-phox gene by the treatment of 0.1 ppm arsenic for 24 hours. This means that biological responses of cardiomyocytes may be altered by ROS induced by low level arsenic without cell death, and this alteration may be detected clearly by molecular biomarkers such as heme oxygenase-1.