Cardiomyocytes In Group Research Articles

Mechanism of Dexmedetomidine Alleviating Myocardial Ischemia-Reperfusion Injury Through Mitochondrial and ER Oxidative Stress Pathway

Objective: To analyze the mechanism of dexmedetomidine through mitochondrial and ER oxidative stress pathway in neonatal rat cardiomyocytes. Methods: SD neonatal rats were selected as the research object, and the control group (Group A), H2O2 group (Group B), dexmedetomidine group (Group C) and dexmedetomidine + H2O2 group were constructed (Group D) four groups of neonatal rat cardiomyocyte oxidative injury models. After drug treatment, the morphology, LDH, GSH, ROS, casease-3,8,9 and 12 activities of neonatal rat cardiomyocytes were detected in turn. The mitochondrial membrane potential and apoptosis rate were detected by flow cytometry, and GRP78 and IRE1 were detected by Western blot α, Expression of Bcl-2 and Bax proteins. Results: 500umol/l was selected as the best reaction concentration of H2O2. H2O2 can cause the disorder of cytoskeleton sequencing and the disappearance of myocardial striations, while dexmedetomidine can reduce the damage of H2O2 to cardiomyocytes. Compared with group A, the activity levels of LDH and ROS in cardiomyocytes in group B increased significantly, and the activity level of GSH decreased significantly. Compared with group B, the activity of GSH in group D was significantly increased, while the activity of LDH and ROS decreased significantly. Compared with group A, the activity levels of Caspase-3,8,9 and 12 in cardiomyocytes of group B increased significantly. Compared with group B, the activity of Caspase-3,8,9 and 12 in cardiomyocytes in group D decreased significantly. The apoptosis rate of cardiomyocytes in group A was (18.36 ± 5.68)%, and that in group D was (39.64 ± 9.36)%. Compared with group A, the apoptosis rate in group B increased significantly; there was no significant change in the apoptosis rate in group C. Compared with group A, the ratio of Bax to Bcl-2 in group B increased significantly; compared with group B, the ratio of Bax to Bcl-2 in group D decreased significantly. Compared with group A, GRP78 and IRE1 α Significantly improved; Compared with group B, GRP78 and IRE1 in group D α Significantly reduced. Conclusion: Dexmedetomidine can inhibit the oxidative stress response and apoptosis induced by H2O2 in neonatal rat cardiomyocytes.

Research into the intervention effect of folic acid on arsenic-induced heart abnormalities in fetal rats during the periconception period

BackgroundThe incidence of CHD is the highest among birth defects and is increasing year to year. CHD seriously harms the health of infants and young children and presents a large economic burden to families and society. The pathogenesis of CHD and preventive measures are the focus of current research. Our research aimed to explore the intervention effect of folic acid on heart abnormalities resulting from sodium arsenic (NaAsO2) exposure during the periconception period.MethodsSixty 35-day-old female SD rats were randomly divided into 5 groups with 12 rats in each group. Group A was the control group. The rats were given distilled water and ordinary chow. The rats in group B were given distilled water containing 75 mg/L NaAsO2 and ordinary chow. The rats in groups C, D, and E were given distilled water containing 75 mg/L NaAsO2 and chow containing 0.53 mg/kg, 5.3 mg/kg, and 10.6 mg/kg folic acid, respectively. The general condition of the embryos and the histopathology of the embryonic hearts were examined. The acetylation levels of histone H3K9 in heart tissues and the expression levels of Mef2C (which is related to heart development) were observed.ResultsThe embryo weight and placental weight of groups B-E were significantly lower than those of group A (P < 0.05). The heart malformation rate of the fetal rats in groups B-E was significantly higher than that of the fetal rats in group A (P < 0.05). We found that the level of H3K9 acetylation in fetal rat cardiomyocytes in groups B-E was significantly higher than that in group A (P < 0.05) and that the level of H3K9 acetylation in groups C-E was lower than that in group B (P < 0.05). The mRNA level of Mef2C in fetal rat cardiomyocytes in group B-E was significantly higher than that in group A (P < 0.05), and the mRNA level of Mef2C in groups C-E was significantly lower than that in group B (P < 0.05).ConclusionSupplementation with folic acid during the periconception period can interfere with the toxic effects of arsenic on the heart. The mechanism may be that lowering the acetylation levels of histone H3K9 in heart tissues leads to decreased expression levels of Mef2C, which may play a protective role in heart development in fetal rats.

Modulation of NOX4 and MAPK Signaling Pathways by Parkia speciosa Empty Pods in H9c2 Cardiomyocytes Exposed to H2O2

Parkia speciosa, a plant that grows abundantly in Southeast Asia region, has been reported to exhibit antioxidant property. This study aimed to investigate the mechanism of antioxidant effects of empty pod extract of Parkia speciosa on hydrogen peroxide-induced oxidative stress in H9c2 cardiomyocytes. There were 4 groups of cardiomyocytes, the negative control, hydrogen peroxide, extract of Parkia speciosa+hydrogen peroxide and quercetin+hydrogen peroxide. Cardiomyocytes of groups 3 and 4 were preincubated for 1 h with 500 µg/ml of the ethyl acetate fraction of the Parkia speciosa extract or 1000 µM quercetin prior to exposure to 500 μM hydrogen peroxide for 1 h. Hydrogen peroxide significantly increased the protein expression of NADPH oxidase 4, superoxide dismutase 1 and p38 mitogen-activated protein kinase, in comparison to the negative control. NADPH oxidase 4 and superoxide dismutase 1 activities as well as reactive oxygen species level were also elevated. These elevations were significantly decreased in the pretreated groups. The Parkia speciosa extract group had comparable effects to that of quercetin. Parkia speciosa extract showed antioxidant property against hydrogen peroxide-induced oxidative stress in H9c2 cardiomyocytes by regulating mitogen-activated protein kinase and NADPH oxidase 4 signaling pathways.

Protective effects of short-term and long-term exercise preconditioning on myocardial injury in rats

To study the role and mechanism of myocardial apoptosis after short-term and long-term exercise preconditioning. Forty-eight male SD rats were randomly divided into control group (C), exhaust group (E), short-exercise preconditioning (S-EP) and long-term exercise preconditioning group (L-EP). Short-term and long-term exercise preconditioning were conducted for 3 days and 3 weeks of repeated intermittent swimming training program. The changes of myocardial cells were observed under light microscope. The serum levels of ischemia-modified albumin(IMA) and creatine kinase-isoenzyme(CK-MB) were detected by ELISA. Real time fluorescence quantitative PCR and Western blot were used to detect the expressions of tumor necrosis factor-α(TNF-α),Caspase-8, Caspase-3 genes and proteins in myocardial tissue. The apoptosis of cardiomyocytes was observed by TUNEL method. Compared with group C, group E had serious myocardial injury. The levels of serum IMA, CK-MB and the expressions of TNF-α, Caspase-8 and Caspase-3 in myocardium were increased (P<0.05). Compared with group E, serum CK-MB and TNF-α and Caspase-8 mRNA in S-EP group were significantly lower than those in group E (P<0.05), but there was no significant difference in serum IMA and Caspase-3 mRNA and protein (P>0.05). The levels of serum IMA, CK-MB and TNF-α, Caspase-8 and Caspase-3 mRNA in L-EP group were significantly lower than those in control group (P<0.05). The apoptosis of cardiomyocytes in group E was obvious. Short-term and long-term exercise preconditioning could inhibit apoptosis. Compared with S-EP group, the apoptosis of L-EP group was significantly decreased. Short-term and long-term exercise preconditioning can reduce myocardial injury after exhaustive exercise, but short-term exercise preconditioning does not alter the expression of Caspase protease. Long-term exercise preconditioning significantly inhibits Caspase-8, 3 mRNA expression and reduces protein synthesis. The inhibitive effects of long-term exercise preconditioning on myocardial cell apoptosis were stronger than those of short-term exercise preconditioning.

Suppressing Apoptosis with Milrinone Simulating Extracorporeal Circulation: A Pilot Study

After cardioplegia, ischemia/reperfusion injury can induce apoptosis. The aim of this study was to evaluate our ex vivo microperfusion model on human myocardium during simulated cardioplegia (cp) and reperfusion (rep). In addition, the aim was to verify the anti-apoptotic properties of the phosphodiesterase 3 inhibitor milrinone. Cardiac biopsies were retrieved from the right auricle of patients undergoing elective CABG prior to induction of cardiopulmonary bypass. Biopsies were exposed to ex vivo conditions with varying periods of cp/rep (30/10, 60/20, 120/40 min). Group I consisted of untreated controls (n=15), Group II of treated controls who had cp/rep (n=15) while Group III had cp/rep+milrinone (n=15). For the detection of apoptosis, anti-activated caspase-3 and PARP-1 cleavage immunostaining were used. The percentage of apoptotic cardiomyocytes in Group I was significantly (P<0.05) lower compared to Group II, revealing a time-dependent increase. In Group III with milrinone treatment, apoptosis was significantly suppressed (P<0.05). Milrinone significantly suppressed apoptosis in our ex vivo setting. This finding warrants further study aiming to evaluate the potential beneficial effects of milrinone on the suppression of ischemia/reperfusion injury in a clinical setting.

Augmented Myocyte Protection And Proliferation In The Infarcted Heart Following Treatment With Cell Lysate From Pharmacologically Preconditioned Mesenchymal Stem Cells

We previously showed that preconditioning of mesenchymal stem cells (MSCs) with diazoxide upregulates expression of multiple trophic factors. We hypothesize that intramyocardial injection of cell lysate from these MSCs (pcMSCs) will prevent myocyte apoptosis, stimulate proliferation and attenuate infarct size. Real time PCR showed higher expression of a series of trophic factors in pcMSCs. Cardiomyocytes pretreated with pcMSC lysate were more resistant to oxidant stress and showed higher phosphorylation of PKC å and PKC ä compared to cardiomyocytes treated with lysate from non preconditioned cells. This effect was blocked by Chelerythrin. For in vivo studies, 50 μl of pcMSC lysate (group 1) or non‐pcMSC lysate (Group 2) or DMEM (group 3) was injected into the acutely infarcted wall. Echocardiography showed improved LV function in group 1 at 6 weeks. Hearts were harvested at day 7 and 6 weeks for Masson Trichrome staining that showed significantly attenuated infarct size, reduced area of fibrosis and well preserved LV wall thickness in group 1 compared to other groups. Immunostaing for Ki67 and á‐actinin showed higher number of proliferating cardiomyocytes in group 1. Capillary density was also highest in the peri‐infarct region in group 1.Conclusion: The trophic factors rich lysate from pcMSC triggers proliferation of cardiomyocytes and preserves LV wall thickness and function.

Multigene adenoviral therapy for the attenuation of ischemia-reperfusion injury after preservation for cardiac transplantation

Objective: The protective effect of adenovirus-mediated ex vivo multigene transfer with superoxide dismutase, a free radical scavenger, and nitric oxide, a vasodilator with anti-inflammatory properties, was examined in the rat heart during experimental ischemia-reperfusion mimicking preservation for cardiac transplantation. Methods: Donor rat hearts (n = 6 per group) were perfused with solution containing adenoviral vector carrying genes for β-galactosidase (group A), endothelial nitric oxide synthase (group B), manganese superoxide dismutase (group C), or both endothelial nitric oxide synthase and manganese superoxide dismutase (group D). Hearts were then implanted heterotopically into the abdomens of recipient rats. Four days later, transplanted hearts were collected, connected to a Langendorff perfusion apparatus, and subjected to 6 hours of ischemia followed by 1 hour of reperfusion. Cardiac function was evaluated with an intraventricular balloon at the beginning of Langendorff perfusion and after ischemia-reperfusion. Results: Effective gene transfection was confirmed with X-gal staining in group A hearts. Positive immunoreactivity for endothelial nitric oxide synthase, manganese superoxide dismutase, or both was present predominantly in cardiomyocytes in group B, C, and D hearts. Percentage recovery of preischemic left ventricular developed pressure was 62.1% ± 7.36% in group A; recoveries were increased to 79.6% ± 6.4%, 86.8% ± 9.1%, and 79.4% ± 6.2% in groups B, C, and D, respectively. Conclusion: These results indicate that adenoviral gene transfer of manganese superoxide dismutase and endothelial nitric oxide synthase can attenuate myocardial ischemia-reperfusion injury, with the former providing the most significant protection. Combined overexpression of manganese superoxide dismutase and endothelial nitric oxide synthase did not enhance myocardial recovery any further.J Thorac Cardiovasc Surg 2003;125:998-1006