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Copyright of Journal of China Medical University is the property of Journal of China Medical University Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Improving the survival rate of cardiomyocytes is the key point to treat most of the heart diseases, and targeting autophagy is a potential advanced therapeutic approach. Monitoring autophagic activity in cardiomyocytes in situ will be useful for studying autophagy-related heart disease and screening autophagy-modulating drugs. Zebrafish, Danio rerio, has been proven as an animal model for studying heart diseases in situ. Taken the advantage of zebrafish, especially the imaging of intact animals, here we generated two stable transgenic zebrafish lines that specifically expressed EGFP-map1lc3b or mRFP-EGFP-map1lc3b in cardiomyocytes under the promoter of myosin light chain 7. We first used a few known autophagy-modulating drugs to confirm their usefulness. By quantifying the density of autophagosomes and autolysosomes, autophagy inducers and inhibitors showed their regulatory functions, which were consistent with previous studies. With the two lines, we then found a significant increase in the density of autophagosomes but not autolysosomes in zebrafish cardiomyocytes at the early developmental stages, indicating the involvement of autophagy in early heart development. To prove their applicability, we also tested five clinical statins by the two lines. And we found that statins did not change the density of autophagosomes but reduced the density of autolysosomes in cardiomyocytes, implying their regulation in autophagic flux. Our study provides novel animal models for monitoring autophagic activity in cardiomyocytes in situ, which could be used to study autophagy-related cardiomyopathy and drug screening.

Objective: To investigate the mechanism of microrna-21 (miR-21) in rat myocardial ischemia-reperfusion injury. Methods: Fifty SPF Wistar rats were selected and randomly divided into 5 groups (n=10), including control group, model group, model +negative control group, model + miR-21 group and model + miR-21 inhibitor group. The model was established by ligation of the left anterior descending coronary artery in rats. After the successful modeling, high-frequency color ultrasound for small animals was used to examine the cardiac function indexes of rats in each group: cardiac ejection fraction (EF), left ventricular peak systolic pressure (LVSP),left ventricular end diastolic pressure (LVEDP) and shortening fraction (FS). Myocardial infarction size and apoptosis rate of myocardial cells were measured. The contents of tumor necrosis factor-α（TNF-α）, interleukin-6（IL-6) and interleukin-10（IL-10） in myocardial tissues were determined by enzyme-linked immunosorbent assay (ELISA) . Reverse transcription polymerase chain reaction (RT-PCR) was used to detect the expression level of miR-21 in myocardial tissue. The expression levels of apoptosis protein and TLR4/NF-κB were detected by western blot. Results: Myocardial infarction occurred in rats in the model group, indicating that the modeling was successful. After modeling, the expression level of miR-21 in rat myocardial tissue decreased significantly, suggesting that miR-21 may protect myocardial cells. After successful modeling, EF, LVSP and FS decreased, LVEDP increased, apoptosis rate of myocardial cells significantly increased, TNF-α and IL-6 expression significantly increased, IL-10 significantly decreased, Bcl-2/Bax expression decreased, caspase-3 expression increased. The expression levels of TLR4 and NF-κB protein phosphorylation increased in rat cardiomyocytes, while the above indicators were improved in model + miR-21 group. Conclusion: Ischemia reperfusion injury of rat cardiomyocytes leads to decreased expression of miR-21, Overexpression of miR-21 can effectively inhibit the TLR4/NF-κB signaling pathway, reduce the level of myocardial apoptosis and the release of inflammatory factors, and thus play a protective role in myocardial cells. [ABSTRACT FROM AUTHOR]

Cardiovascular disease is a severe threat health worldwide, and circRNAs have been shown to be correlated with the development of cardiovascular disease. Expression of circ‐ITCH and miR‐17a‐5p was evaluated by RT‐qPCR. Cell viability was measured using CCK‐8. Flow cytometry was applied to measure apoptosis rate. Binding between miR‐17‐5p and circ‐ITCH was detected via luciferase reporter assays. Levels of ATP in cells were examined with ATP testing. Western blot was used to evaluate apoptosis‐related proteins and proteins in Wnt/β‐catenin signalling pathway. H2O2 induced apoptosis of H9c2 cells and lowered cell viability as well as ATP levels and circ‐ITCH expression. After overexpression, circ‐ITCH enhanced cell viability and ATP concentration. Meanwhile, apoptosis was inhibited. MiR‐17‐5p was the target of circ‐ITCH as evidenced by luciferase report assays, with higher expression in H2O2‐induced H9c2 cells. Knockdown of miR‐17‐5p could promote cell viability and level of ATP and curb apoptosis and p53 and PARP expression. Moreover, overexpressed miR‐17‐5p could reverse the function of upregulated circ‐ITCH. Wnt3a, Wnt5a and β‐catenin in Wnt/β‐catenin signalling pathway were increased after H2O2 induction. Suppression of Wnt/β‐catenin signalling pathway could initiate the process of injury in H9c2 cells. Circ‐ITCH could protect myocardial cells from injuries caused by H2O2 by suppressing apoptosis while miR‐17‐5p played a reverse role, which could upregulate apoptosis and inhibit cell viability via Wnt/β‐catenin signalling pathway. [ABSTRACT FROM AUTHOR]

Backgrund/Aims: Ischemia reperfusion (I/R) promotes the severity of cardiomyocyte injury. Long noncoding RNAs (LncRNAs) are key regulators in cardiovascular diseases. However, the association between LncRNAs and myocardial I/R injury has not been thoroughly characterized to date. We attempted to clarify the potential biological role of a LncRNA (E230034O05Rik), which we named hypoxia/reoxygenation (H/R) injury-related factor in myocytes (HRIM), by investigating the differential expression of LncRNAs between groups of myocytes exposed to either a normal level of oxygen or to H/R. Methods: Microarray analysis was used to determine analyze the global differential expression of LncRNAs in H9c2 myocytes exposed either to a normal level of oxygen or to H/R. Target LncRNA levels were further verified in vitro and ex vivo by real-time polymerase chain reaction (qPCR). Cell viability was analyzed using the Cell Counting Kit-8 assay. Autophagy levels were confirmed by Western blotting, transmission electron microscopy, and autophagic double-labeled (mRFP-GFP-LC3) adenovirus analyses. Results: Gene expression profiling revealed that 797 LncRNAs and 1898 mRNAs were differentially expressed in the H/R group compared with the normal oxygen group. Among these LncRNAs and mRNAs, 6 upregulated LncRNAs and 2 downregulated LncRNAs in the H/R group were selected and further validated by qPCR in vitro and ex vivo. Additionally, LncRNA-HRIM was inhibited by specific siRNAs in H9c2 myocytes exposed to H/R. The inhibition of LncRNA-HRIM by siRNA prevented cell death by suppressing excessive autophagic activity in myocytes, This finding suggests a detrimental role of LncRNA-HRIM in the regulation of I/R injury. Conclusions: LncRNAs are involved in H/R injury of H9c2 myocytes. Inhibition of LncRNA-HRIM increased cell viability by reducing autophagy in myocytes during H/R.

Long non-coding RNAs (lncRNAs) are bound up with the regulation of various diseases. Here, we probed into the effect of lncRNA colorectal neoplasia differentially expressed (CRNDE) on heart failure (HF). The pathological alterations and cell apoptosis of heart tissues were observed by hematoxylin–eosin and TUNEL staining. The viability or apoptosis of mouse myocardial cells HL-1 was tested by XTT or flow cytometry. The interaction between lncRNA CRNDE and poly-ADP-ribose polymerase 1 (PARP-1) was verified by RNA immunoprecipitation and RNA pull-down. The stability of the PARP-1 protein and the acetylation level of high mobility group box-1 (HMGB1) were determined by cycloheximide-chase and immunoprecipitation, respectively. LncRNA CRNDE expression was decreased in HF mice tissues and doxorubicin (Dox)-treated HL-1 cells, whereas PARP-1 and HMGB1 were increased. The overexpression of lncRNA CRNDE restrained HL-1 cell apoptosis induced by Dox. Moreover, the interaction between CRNDE and PARP-1 was corroborated, CRNDE negatively regulated PARP-1 expression, and the overexpression of CRNDE reduced PARP-1 protein stability. In HL-1 cells, PARP-1 positively regulated the acetylation level and cytoplasm translocation of HMGB1. CRNDE restrained Dox-induced apoptosis in mouse myocardial cells via the PARP-1/HMGB1 pathway. [ABSTRACT FROM AUTHOR]

In this study, the regulation of miR-15b-5p on myocardial ischemia reperfusion (I/R) injury-induced arrhythmia and myocardial apoptosis was investigated in mice. We observed the change in miR-15b-5p expression after mice suffered from myocardial I/R injury and the change in myocardial injury, infarct size, apoptosis, tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), superoxide dismutase (SOD) and malondialdehyde (MDA) after down-regulation of miR-15b-5p expression. The negative regulation of miR-15b-5p to KCNJ2 as well as whether cardioprotective effect formed by miR-15b-5p down-regulation relied on the increase of KNCJ2 expression were measured by dual-luciferase reporter assay system. miR-15b-5p expression increased and KCNJ2 mRNA and protein expressions decreased after myocardial ischemia reperfusion (all P < 0.05). miR-15b-5p negatively regulated KCNJ2 in a targeted way. Down-regulating miR-15b-5p expression or increasing KCNJ2 expression significantly decreased the incidence of arrhythmia, infarct size and apoptosis after myocardial I/R and lowered MDA content in the myocardial tissue as well as IL-6 and TNF-α content in the blood (all P < 0.05). KCNJ2 gene knockout reversed the above cardioprotective effect formed by miR-15b-5p down-regulation (P < 0.05). Down-regulating miR-15b-5p expression or up-regulating KCNJ2 expression improves arrhythmia after mice suffered from myocardial I/R injury and inhibits myocardial apoptosis. • Myocardial ischemia reperfusion can effectively remedy myocardial infarction. • miR-15b-5p can regulate cardiac disease, apoptosis and inflammatory injury. • miR-15b-5p can restrain I/R injury-induced arrhythmia and myocardial apoptosis. [ABSTRACT FROM AUTHOR]

Objective: The study intends to explore the functions of maternal high-fat diet exposure on progeny weight and heart.Methods: Sprague-Dawley (SD) rats, fed on a high-fat diet, were used to establish a model of weight gain before and during pregnancy. The body and cardiac weight of neonatal, 1-month- and 3-month-old rats were measured. The morphology of myocardial cells was observed by hemotoxylin and eosin (H&E) staining. The expression of caspase-3, 8, 9 was measured by qRT-PCR and western blot.Results: Normal pregnant rats, fed on a high-fat diet throughout pregnancy, had a significant increase in body and cardiac weight of their neonates, and more fat deposition in myocardial cells and an increased expression of caspase-3, 8, 9, compared with that of the normal pregnant rats + normal diet group. These phenomena were relieved through later diet control. Pregnant rats, which fed on a high-fat diet throughout pregnancy, showed more adverse effects on neonatal body and cardiac weight, myocardial cell fat deposition, and the expression of caspase-3, 8, 9, compared with pregnant rats exposed to high-fat diet + normal diet and pregnant rats exposed to high-fat diet + normal diet + exercise. These phenomena cannot be fully restored via controlling later diet.Conclusions: Our results stated that a proper diet before and during pregnancy was important for the cardiac health of offspring. [ABSTRACT FROM AUTHOR]

Protective effect of fluvastatin (Flu) on myocardial cells in mice with acute myocardial infarction (AMI) and the mechanism were explored. Forty C57B/L6 mice in similar physiological status were selected and randomly divided into sham operation (Sham) group (n=10), AMI group (n=10), Flu group (n=10) and Flu + Angiotensin II (Ang II) (Ang II) group (n=10). The pathological changes in heart tissues were detected via hematoxylin and eosin (H&E) staining, and apoptosis of myocardial cells was detected via terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay. Moreover, the expression levels of malondialdehyde (MDA) and superoxide dismutase (SOD) were determined using relevant kits, and the expression levels of Ras homolog gene family (Rho)-associated coiled-coil protein kinase 1 (ROCK1), ROCK2, B-cell lymphoma-2 (Bcl-2), Bcl-2 associated X protein (Bax) and nuclear factor-κB (NF-κB) in the infarction region were determined using Western blotting. The infarction area in mice in Flu group was significantly smaller than that in AMI group. In AMI group, the level of MDA in the serum and infarction tissues was remarkably higher than that in Sham group (P<0.05), while that of SOD significantly declined (P<0.05). The level of MDA in Flu group was obviously lower than that in AMI group (P<0.05). The expression levels of Bax, NF-κB, ROCK1 and ROCK2 were obviously higher in AMI group than those in Sham group, while they were obviously lower in Flu group than those in AMI group (P<0.05). After the Rho member A (RhoA)/ROCK pathway agonist Ang II was added, the mitigation effect of Flu on myocardial apoptosis in the infarction region in AMI mice was evidently weakened. Flu mitigates AMI-induced myocardial apoptosis in mice, and the possible mechanism is that the inflammatory and oxidative stress responses activated and mediated by RhoA/ROCK are effectively inhibited. [ABSTRACT FROM AUTHOR]

The aim of this study is to explore the effect of flavonoids from Rosa roxburghii Tratt (FRRT) on doxorubicin (DOX)-induced autophagy of myocardial cells. Primary isolation and culture of myocardial cells and H9C2 myocardial cell lines from 1 to 3-day-old rats were performed, myocardial cells were incubated using 5 μmol/L DOX and a cardiotoxicity model was established, intervention was conducted via FRRT, and the ultrastructure of myocardial cells was observed under a transmission electron microscope. The expressions of LC3-II and P62 proteins were detected through immunofluorescence and Western blotting. The ultrastructure showed a large quantity of autophagic vacuoles of the cells in DOX group with poor cell state. After the FRRT intervention, only a small quantity of autophagic vacuoles appeared in the myocardial cells, and there were many coarse microvilli on the cell surface. The expression of P62 protein was reduced in DOX group, while that in FRRT group was increased (p < 0.01). In conclusion, FRRT exerts a protective effect in the DOX-induced cardiotoxicity by down-regulating DOX-induced autophagy of myocardial cells. [ABSTRACT FROM AUTHOR]

External electric fields (E) induce a spatially heterogeneous variation in the membrane potential (ΔVm) of cardiomyocytes that, if sufficiently large, results in an action potential and contraction. Insights into the phenomenon of ΔVm induction by E have been classically gained with electromagnetic models due to the lack of adequate experimental approaches. However, it is not clear yet how reliable these models are. To assess the accuracy of commonly used models, a reference 3D numerical model for cardiomyocytes (NMReal) was developed, consisting of the cell membrane shell reconstructed from rendered confocal microscopy images of freshly isolated ventricular myocytes. NMReal was used to estimate the E-induced maximum ΔVm values (ΔVmax), which were compared with estimates from seven other electromagnetic models. Accurate ΔVmax estimates (average error < 2%) were obtained with a less complex 3D model (NM3D) based on the extruded 2D image of the cell longitudinal section. Acceptable ΔVmax estimates (average error < 5%) were obtained with the prolate spheroid analytical model (PSAM) when the angle of E incidence and the cell major axis was < 30°. In this case, PSAM, a much simpler model requiring only the measurement of the longitudinal and transversal cell dimensions, can be a suitable alternative for ΔVmax calculation. Graphical abstract (A) Confocal images of the cell were used to reconstruct the realistic geometry of cardiomyocytes (NMReal). (B) NMReal was used to estimate the maximum variation in the transmembrane potential (ΔVmax) induced by an external electric field (E) applied at different angles with respect to the cell major axis. Plus (anode) and minus (cathode) signs indicate electrode position (E direction is from minus to plus). (C) Relative error (vs. NMReal) of ΔVmax estimation with simplified electromagnetic models, presented in descending order of accuracy (left-to-right, top-to-bottom). NM2D: 2D numerical model based on the longitudinal cell image; NM3D: numerical model based on the z extrusion of NM2D; EAM, PSAM, and CAM: ellipsoidal, prolate spheroidal, and cylindrical analytical models, respectively; PNM and CNM: parallelepipedal and cylindrical numerical models, respectively. [ABSTRACT FROM AUTHOR]

Objective: To determine the underlying mechanism of miR-34b/c in regulating doxorubicin (Dox)-induced myocardial cell injury. Methods: The viability of mouse myocardial cells HL-1 was detected by MTT assay. The apoptosis of HL-1 cells was detected by TUNEL assay. mRNA expressions of ITCH, TNF-α and IL-6 were measured by qRT-PCR. Protein levels of ITCH, NF-κB, TNF-α and IL-6 were measured by western blot. Dual luciferase assay was performed to detect the regulation of miR-34b/c on ITCH. Mouse model of cardiomyopathy was induced by intraperitoneal injection of Dox. Results: Dox reduced HL-1 cell viability and activated NF-κB pathway in HL-1 cells. miR-34b/c expressions were gradually up-regulated and ITCH expression was gradually down-regulated in Dox-treated HL-1 cells. miR-34b/c expression had negative correlation with the mRNA expression of ITCH. Besides, ITCH was a target of miR-34b/c. miR-34b/c mimic reduced cell viability, suppressed ITCH expression, increased TNF-α and IL-6 level, and promoted NF-κB expression in nucleus and cytoplasm of HL-1 cells. Whereas silencing miR-34 protected HL-1 cells through regulating ITCH. Finally, we demonstrated miR-34 antagomir-protected myocardial cells in mouse model of cardiomyopathy. Conclusion: miR-34b/c decreased HL-1 cell viability and promoted the secretion of proinflammatory cytokines in Dox-induced myocardial cells through ITCH/NF-κB pathway. [ABSTRACT FROM AUTHOR]

OBJECTIVE: The aim of this study was to investigate the effect of micro ribonucleic acid (miR)-497 on myocardial cell apoptosis in rats with myocardial ischemia/reperfusion (I/R) through the mitogen-activated protein kinase (MAPK)/extracellular regulated protein kinase (ERK) signaling pathway. MATERIALS AND METHODS: A rat model of myocardial I/R was established, myocardial cells were extracted, and miR-497 was inhibited by inhibitors and overexpressed using miRNA mimics. The cell apoptosis rate was detected by flow cytometry and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. The interaction between miR-497 and ERK was determined by dual-luciferase reporter gene assay. The change in the protein level was measured via Western blotting (WB). RESULTS: Up-regulation of miR-497 promoted myocardial cell apoptosis, and the 3'-untranslated region (3'-UTR) of ERK was highly conserved to combine with miR-497. The luciferase reporter gene assay showed that the transfection of miR-497 could significantly inhibit the relative luciferase activity in cells. CONCLUSIONS: MiR-497 overexpression significantly down-regulated the ERK expression at messenger RNA (mRNA) and protein levels in cells. MiR-497 plays an important role in regulating I/R injury-induced myocardial cell apoptosis by targeting the ERK-induced apoptosis pathway. [ABSTRACT FROM AUTHOR]

Acute myocardial infarction (AMI), as a severe consequence of coronary atherosclerotic heart disease, always contributes to the loss of myocardial cells. Mounting evidence shows that annexin protects the myocardium from ischemic injury. In this study, we examine the inhibition of annexin A3 (ANXA3) on AMI through the phosphatidylinositide 3‐kinase/protein kinase B (PI3K/Akt) signaling pathway. We selected rats to build an AMI model which was then assigned into different groups. The hemodynamic parameters after transfection were detected by using enzyme‐linked immunosorbent assay. The effect of silencing of ANXA3 on inflammatory reaction and the PI3K/Akt signaling pathway was assessed. Rats transfected with ANXA3‐short hairpin RNA had alleviated hemodynamics, inflammatory reaction, decreased infarct size, α‐smooth muscle actin, Collagen I, and Collagen III as well as an increased vascular endothelial growth factor. Silencing ANAX3 would promote repair and healing of myocardial tissue by activation of the PI3K/Akt signaling pathway. Collectively, our study provides evidence that the downregulation of ANXA3 promotes the repair and healing of myocardial tissues by activating the PI3K/Akt signaling pathway. Collectively, our study provides evidence that the downregulation of ANXA3 promotes the repair and healing of myocardial tissues by activating the PI3K/Akt signaling pathway. [ABSTRACT FROM AUTHOR]

OBJECTIVE: To investigate the effect of micro ribonucleic acid (miR)-101a on myocardial cell apoptosis in the rat model of acute myocardial infarction (AMI) and its regulatory mechanism. MATERIALS AND METHODS: A total of 30 Sprague-Dawley (SD) rats were randomly divided into the Sham group, Model group, and miR- 101a mimic group, with 10 rats in each group. The rat model of AMI was established by the ligation of the anterior descending coronary artery. The rat left ventricular end-diastolic volume (LVEDV) and left ventricular end-systolic volume (LVESV) were detected using a color Doppler ultrasonic apparatus. Subsequently, the miRNA online database (TargetScan) was adopted to predict miRNAs that could be able to regulate TGF-ß1. Hematoxylin and eosin (H&E) staining was conducted to reveal the histopathological morphology changes in the rat heart. The serum levels of cysteinyl aspartate specific proteinase-3 (Caspase-3) and Bcl-2-associated X protein (Bax) in rats were detected via enzyme-linked immunosorbent assay (ELISA). Moreover, the expression levels of the transforming growth factor-beta l (TGF-ß1) and c-Jun N-terminal kinase (JNK) in rat heart were measured via Western blotting. RESULTS: Through searching miRNA database, miR-101a and TGF-ß1 messenger RNAs (mRNAs) had binding sites in the 3' untranslated region (3'UTR). Compared with those in Sham group, the rat LVEDV and LVESV were notably elevated, the histopathological morphology of the heart was seriously damaged, the apoptotic rate of myocardial cells and the levels of TGF-ß1 and JNK proteins significantly increased in the Model group. Additionally, compared with those in the Model group, the LVEDV and LVESV of rats in miR-101a mimic group were significantly reduced, the histopathological morphology of the heart was markedly improved, and the apoptotic rate and the levels of TGF-ß1 and JNK in rat heart were remarkably decreased. CONCLUSIONS: The myocardial cell apoptosis in AMI rats can be suppressed by overexpression of miR-101a by inhibiting the TGF-ß1/JNK signaling pathway. [ABSTRACT FROM AUTHOR]

OBJECTIVE: Myocardial cell apoptosis is an important pathologic basis of ischemia- reperfusion injury (I/R). PI3K/Akt signaling pathway involves in cell growth, survival, and apoptosis regulation, thus playing an important role in the protection of I/R injury. PTEN is a negative regulatory factor of PI3K/Akt signaling pathway. This study established rat I/R injury model after AMI and myocardial cell I/R injury model to explore the regulatory role of PTEN-PI3K/Akt signaling pathway in myocardial I/R injury in vivo and in vitro. MATERIALS AND METHODS: Rat myocardial I/R injury model was established. PTEN and p-Akt expressions in myocardial tissue were compared. H9C2 cells were incubated in I/R condition for 12 h, followed by reoxygenation for 12 h. H9C2 cells were divided into three groups, including I/R+pSicoR-Blank, I/R+pSicoR-PTEN, and I/R+pSicoR-PTEN+VO-Ohpic. PTEN, p-Akt, Bcl-2, and Bax expressions were detected. Cell apoptosis was measured by flow cytometry. RESULTS: PTEN expression significantly increased, while p-Akt level markedly declined in myocardial tissue in I/R group compared with Sham group. Temporary PTEN downregulation and p-Akt elevation appeared at 2 h after I/R. I/R treatment markedly enhanced PTEN and Bax expressions, increased cell apoptosis, and reduced p-Akt and Bcl-2 levels. PTEN overexpression significantly enhanced Bax expression and cell apoptosis, while declined p-Akt and Bcl-2 in H9C2 after I/R. PTEN inhibited by VO-Ohpic markedly downregulated p-Akt and Bcl-2 expressions, whereas reduced Bax level and cell apoptosis. CONCLUSIONS: The overexpression of PTEN aggravated myocardial cell apoptosis after I/R. The blockage of PTEN enhanced PI3K/Akt signaling pathway and attenuated cell apoptosis induced by I/R. [ABSTRACT FROM AUTHOR]

To better understand the mechanism of photodynamic cardiac ablation, we studied the effects of a photosensitization reaction (PR) performed during the first 3 min after rat myocardial cells were exposed to talaporfin sodium. A 3-mm-square microelectrode array with 64 electrodes was used to continuously measure the action potentials of the myocardial cells. A 30 μg/mL talaporfin sodium solution, a chlorine photosensitizer, was used, along with a 663-nm red diode laser (86 mW/cm2 for up to 600 s). The first trough of the measured action potential waveform corresponding to Na+ dynamics decreased exponentially with increasing PR duration. The average decay time of the exponential function from PR onset was 20.1 s. Marked morphological changes in the myocardial cells was observed after the PR. These results indicated that the behavior of the action potential waveform measured by the microelectrode array might be used as a less invasive method to evaluate the electrophysiological effects of a PR on myocardial cells. [ABSTRACT FROM AUTHOR]

Background: We investigated the binding of talaporfin sodium with albumin and its photocytotoxicity during temperature changes by measuring absorbance spectra. The targeted tissue temperature differs according to the procedure. The photocytotoxicity efficiency should be investigated quantitatively because efficiency changes arising from temperature changes are expected. Materials and methods: The temperature dependence of talaporfin sodium binding with human serum albumin (0-20 mg/mL), high-density lipoprotein (0-0.04 mg/mL), and low-density lipoprotein (0-0.14 mg/mL) was investigated at 17°C, 27°C, and 37°C by measurement of absorbance spectra. Cell lethality was measured using a water-soluble tetrazolium-8 assay at 2 h after the photosensitization reaction at 17°C and 37°C. Results: The binding ratios of talaporfin sodium with high-density lipoprotein decreased by 6.3% and those with low-density lipoprotein decreased by 12.8% when the temperature increased from 17°C to 37°C. Cell lethality increased significantly with a temperature rise from 17°C to 37°C at irradiation exposure of 20 and 40 J/cm2 and talaporfin sodium concentration of 20 μg/mL. Conclusions: From our in vitro data, we can predict that the change in photocytotoxicity efficiency would be negligible with a temperature decrease of <5°C from the body temperature in the case of photodynamic ablation with a short drug-light interval. [ABSTRACT FROM AUTHOR]

Background To obtain therapeutic condition precisely by in vitro experiment, we studied the irradiance dependence of the electrical conduction blockage caused by a photodynamic reaction using a high extracellular concentration of talaporfin sodium on a novel in vitro cardiomyocyte electrical conduction wire. Methods The cardiomyocyte wires were constructed on patterned cultivation cover glass, which had cultivation areas 60 μm in width, and a maximum length of 10 mm. The talaporfin sodium concentration was set to 20 μg/mL. The photodynamic reaction with a high extracellular photosensitizer concentration was performed with a short time interval (approximately 15 min) between photosensitizer exposure and irradiation. A 663-nm laser was applied to the cardiomyocyte wire, and the irradiance was varied between 3 and 120 mW/cm 2 . The cardiomyocyte electrical conduction was evaluated using the cross-correlation function of intracellular Ca 2+ probe fluorescence brightness from an upper and lower section outside the laser irradiation area of a wire every 10 s, which lasted up to 600 s. Results The onset of electrical conduction blockage was defined by an 85% decrease in the cross-correlation function, compared with its initial value. The time for the electrical conduction blockage decreased from 600 to 300 s as the irradiance was increased. Also, the probability of electrical conduction blockage was found to increase with increasing irradiance. Conclusions We found a strong dependence on the irradiance for the time and probability of electrical conduction blockage. [ABSTRACT FROM AUTHOR]

Objectives As we all know, oxidative stress was one of the most important causes of ischemia-reperfusion injury. And it was reported that Nrf-2 as an important regulator for oxidative stress could be activated by Linarin. Thus it would be interesting to find whether Linarin could inhibit ischemia-reperfusion injury through activating Nrf-2. Methods In this study, cell activity was detected by MTT assay and caspase-3 activity detection kit. And the expressions or activities of some signal proteins were evaluated by western-blot or activity detection kits. At last, the effect and mechanism of Linarin on heart tissues were verified in the ischemia-reperfusion model of isolated hearts. Results The proliferation activity of cell was inhibited while the apoptosis rate was increased after hypoxia-reoxygenation. However, Linarin could inhibit these two variations. It was found that these effects of Linarin were related with the activation of Nrf-2 through PI3 K/Akt signaling pathway. Meanwhile, the anti-oxidative enzymes, regulated by Nrf-2, were enhanced to against the oxidative stress caused by hypoxia-reoxygenation. And with the inhibition of oxidative stress, some proliferation and apoptosis related proteins such as NF-kB and Cytochrome C were adjusted to support the viability of cells. At last, these results were verified in the ischemia reperfusion experiment of isolated hearts. Conclusions From this study, we assured that LIN could protect myocardial tissue from ischemia-reperfusion through activating Nrf-2. [ABSTRACT FROM AUTHOR]

The present study aimed to investigate the association between myocardial cell apoptosis and calpain-1/caspase-3 expression in a rat model of hypoxic-ischemic brain damage (HIBD). A total of 64 newborn rats were divided into control (n=8; sacrificed on day 7) and HIBD groups (n=56). HIBD group rats were sacrificed 2, 12 or 24 h, or 2, 3, 5 or 7 days following HIBD (n=8/group). A terminal deoxynucleotidyl transferase dUTP nick-end labeling assay was performed to detect myocardial apoptotic cells and calculate the apoptosis index (AI), reverse transcription-polymerase chain reaction was performed to detect myocardial calpain-1/caspase-3 mRNA expression levels and a western blot analysis was conducted to detect calpain-1 protein expression levels. The correlations between calpain-1 and caspase-3 expression levels and AI were analyzed. The results demonstrated that apoptotic myocardial cells in the HIBD groups were markedly increased compared with the control group, with AI peaking in the day 3 group. Caspase-3 and calpain-1 mRNA expression levels were increased from 2 and 12 h following HIBD, respectively, with the most elevated levels in the day 2 group. Compared with the control group, calpain-1 protein expression levels were increased from 2 h, with the greatest expression levels in the day 3 group (P<0.05). Calpain-1 mRNA and protein (76/80 kDa) expression levels demonstrated positive linear correlations with AI (r=0.786, P=0.001; and r=0.853, P=0.001, respectively) Caspase-3 mRNA expression levels were positively correlated with AI (r=0.894; P=0.001). In conclusion, the present study demonstrated that in rats with HIBD, there is a positive correlation between increased apoptosis of myocardial cells and expression levels of calpain-1 and caspase-3. [ABSTRACT FROM AUTHOR]

OBJECTIVE: Myocardial apoptosis is an important pathologic basis of ischemia-reperfusion injury (I/R). Transforming growth factor β1 (TGFβ1) participates in the regulation of oxidative damage and apoptosis. TGFβ1 is upregulated in the repair process of I/R injury. It is speculated that TGFβ1 over-expression is involved in the endogenous protective mechanism of I/R injury. This study explores the significance of TGFβ1 in myocardial cell apoptosis after I/R. MATERIALS AND METHODS: Rat myocardial I/R injury model was established. Left ventricular ejection fraction (LVEF) and Left ventricular fractional shortening (LVFS) were detected by ultrasonic cardiogram. TGFβ1 expression in the myocardium was tested. H9C2 cells were cultured under ischemic hypoxic condition for 6 h, and then were treated by reoxygenation for 6 h to simulate I/R model. H9C2 cells were divided into three groups, including I/R+pIRES2-Blank, I/R+pIRES2 TGFβ1, and I/R+pIRES2-TGFβ1+LY364947. TGFβ1 mRNA and protein levels were evaluated. Cell apoptosis and reactive oxygen species (ROS) were determined by flow cytometry. RESULTS: LVEF and LVFS significantly decreased in I/R group compared with Sham group. TGFβ1 mRNA and protein expressions in myocardium from I/R group up-regulated than the control. I/R treatment markedly elevated TGFβ1 mRNA and protein levels, increased ROS content, and enhanced cell apoptosis in H9C2 cells. Over-expression of TGFβ1 significantly weakened ROS production and apoptosis in H9C2 cells after I/R. TGFβ receptor inhibitor LY364947 restrained ROS production and apoptosis attenuation in H9C2 cells treated by TGFβ. CONCLUSIONS: TGFβ1 alleviates myocardial cell apoptosis after I/R. Blocking TGFβ1 attenuates the protective effect of TGFβ1 on I/R injury. [ABSTRACT FROM AUTHOR]

MicroRNA-122 has been reported to play a potential role in the apoptosis of myocardial cells. However, the effect of miR-122 in regulating myocardial ischemic injury has not been previously addressed. This study aimed to investigate the effect and the molecular basis of miR-122 on myocardial ischemic injury. Using the hypoxia/reoxygenation (H/R) model of rat cardiomyocytes H9C2 in vitro , we found that miR-122 was highly expressed in H9C2 cells after H/R treatment. Overexpression of miR-122 by recombinant adeno-associated viral vector infection markedly promoted the apoptosis of H9C2 cells induced by H/R treatment, whereas miR-122 inhibition significantly decreased cell apoptosis. Dual-luciferase reporter assay and western blot assay revealed that GATA-4 was a direct target gene of miR-122, and miR-122 suppressed the expression of GATA-4 via binding to its 3′-UTR. We further identified that overexpression of miR-122 inhibited the expression of GATA-4 at the mRNA and protein levels, whereas the inhibition of miR-122 upregulated the expression of GATA-4. Moreover, GATA-4 was poorly expressed in H/R H9C2 cells and the apoptosis induced by H/R was associated with the decrease in GATA-4 expression. Importantly, silencing of GATA-4 apparently abrogated the inhibitory effect of anti-miR-122 on H/R-induced cell apoptosis. In conclusion, these findings indicate that downregulation of miR-122 alleviates cardiomyocyte H/R injury through upregulation of GATA-4 expression, supplying a novel molecular target for myocardial ischemic injury. [ABSTRACT FROM AUTHOR]

Background To investigate the immediate occurrence of irreparable severe damage to myocardial cells up to 10 min after a photodynamic reaction with a high concentration of photosensitizer outside cells, we measured the damage response time and the parameters that govern the response time via rat myocardial Ca 2+ concentration. In our proposed method for catheter ablation of tachyarrhythmia by photodynamic reaction, there are two components to the electrical conduction block: an immediate electrical conduction block of several tens of seconds to several minutes, and a permanent electrical conduction block. Methods Rat myocardial intracellular Ca 2+ concentration changes before, during and after the photodynamic reaction with a high concentration of photosensitizer outside myocardial cells were continuously observed using a Fluo-4 AM Ca 2+ probe. Talaporfin sodium with 663-nm excitation was used to induce the photodynamic reaction. Talaporfin concentration was 10–30 μg/ml, radiant exposure was 10–40 J/cm 2 , and irradiance was 30–290 mW/cm 2 . We evaluated the response time of irreparable severe damage to myocardial cells, according to Ca 2+ concentration. Results The response time of the defined severe damage occurrence to myocardial cells ranged from 200 to 500 s. The response time decreased with increasing irradiance and photosensitizer concentration, but exhibited no significant change with total radiant exposure. Conclusions We found that severe myocardial cell damage caused by a photodynamic reaction with a high concentration of photosensitizer outside cells occurred within a few minutes, which might be useful for catheter ablation for tachyarrhythmia that needs immediate response during the ablation procedure. [ABSTRACT FROM AUTHOR]

Microwaves may exert adverse biological effects on the cardiovascular system at the integrated system and cellular levels. However, the mechanism underlying such effects remains poorly understood. Here, we report a previously uncharacterized mechanism through which microwaves damage myocardial cells. Rats were treated with 2450 MHz microwave radiation at 50, 100, 150, or 200 mW/cm2 for 6 min. Microwave treatment significantly enhanced the levels of various enzymes in serum. In addition, it increased the malondialdehyde content while decreasing the levels of antioxidative stress enzymes, activities of enzyme complexes I-IV, and ATP in myocardial tissues. Notably, irradiated myocardial cells exhibited structural damage and underwent apoptosis. Furthermore, Western blot analysis revealed significant changes in expression levels of proteins involved in oxidative stress regulation and apoptotic signaling pathways, indicating that microwave irradiation could induce myocardial cell apoptosis by interfering with oxidative stress and cardiac energy metabolism. Our findings provide useful insights into the mechanism of microwave-induced damage to the cardiovascular system. [ABSTRACT FROM AUTHOR]

Summary Background We have proposed an application of photodynamic reaction for less-heated myocardial ablation which employs talaporfin sodium. Intracellular photodynamic reactions with ongoing uptake have the ability to induce apoptosis over time, raising the possibility of extending the lesion depth. The objective of this study was to understand how, in myocardial cells, the late cell survival levels change by incubation time with talaporfin sodium, and what dependence talaporfin sodium uptake has on the duration of incubation with talaporfin sodium in vitro . Methods Rat myocardial cells were incubated with talaporfin sodium for 5–360 min and intracellular concentrations measured using a fluorescence micro-plate reader after wash. Cell survival was measured using a water-soluble tetrazolium assay at 2 and 24 h after a photodynamic reaction using a red diode laser of 660 nm, following 15–180 min of incubation with talaporfin sodium. Cells were stained with Hoechst 33342 to observe nuclear changes. Results Intracellular talaporfin sodium concentration increased with incubation time, with a marked increase between 0 and 60 min. Cell survival at 24 h decreased by 20% when the duration of incubation with talaporfin sodium was extended from 15 to 30 min. Following incubation time of 30–180 min with talaporfin sodium, cell survival was decreased by approximately 30% between measurements at 2 and 24 h. The intracellular talaporfin sodium concentration that induced higher levels of late cell death with cell nuclei fragmentation in these cells was approximately 0.2 μg/mL. Conclusion We obtained the characteristics of late cell death occurrence and talaporfin sodium uptake to myocardial cell with various incubation times with talaporfin sodium. [ABSTRACT FROM AUTHOR]