第27届国际园艺大会将于2006年8月13—19日在韩国汉城召开

由国际园艺学会和韩国园艺学会共同主办的第27届国际园艺大会将于2006年8月13～19日在韩国汉城召开(同期举办展览)。会议主题是“全球园艺:多样性与和谐”。会议组织委员会主席为韩国庆熙大学李政明(Jung MyungLee)教授,副主席为韩国汉城市立大学JeongSikLee教授和韩国汉城大学     

Role of glycine receptor in protection of glycine against anoxia/reoxygenation injury in cardiomyocytes

AIM:To investigate whether glycine receptor is involved in the protection of glycine against anoxia/reoxygenation injury in cardiomyocytes by detecting oxygen free radical metabolism, apoptosis and intracellular calcium overload. METHODS:The neonatal rat cardiomyocytes were cultured and exposed to anoxia and reoxygenation (A/R) in the presence of glycine receptor antagonist, glycine or in free chloride buffer. The superoxide dismutase (SOD) activity, the contents of malondialdehyde (MDA) and nitric oxide (NO), the intracellular free calcium concentration and the apoptotic rate in the cardiomyocytes were determined. RESULTS:SOD activity and NO content in cardiomyocytes were lower, but MDA content, intracellular free calcium concentration and apoptotic rate in cardiomyocytes were higher in A/R group than those in control. Pretreatment with glycine inhibited the above changes caused by A/R, which was reversed by strychnine treatment and in the free chloride medium. CONCLUSIONS:Glycine inhibits free radical production, attenuates calcium overload, decreases apoptotic rate and increases SOD activity and NO release in cardiomyocytes exposed to A/R. These findings suggest that glycine exerts a protective effect against A/R injury via glycine receptor and glycine protects the neonatal rat cardiomycytes from A/R-induced injury in a chloride-dependent manner.     

Role of ROS/PKC/p38 MAPK pathway in protective effects of polysaccharide from Fructus cornion rat cardiomyocytes against hypoxia-reoxygenation injury

AIM: To investigate the effect of polysaccharide from Fructus corni(PFC) on cardiomyocytes against hypoxia/reoxygenation (H/R) injury and its possible relationship with ROS/PKC/p38 MAPK pathway.METHODS: Primary cardiomyocytes were isolated from neonatal SD rats and randomly divided into normal group, H/R group, PFC (20 mg/L, 100 mg/L and 200 mg/L) preconditioning+H/R groups, chelerythrine+PFC (100 mg/L)+H/R group and SB203580+PFC (100 mg/L)+H/R group. The cell viability was measured by inverted microscopic observation. Apoptosis in the cardiomyocytes was detected by Hoechst 33258 staining and fluorescence microscopy. The levels of lactate dehydrogenase (LDH) and superoxide dismutase (SOD) in the cell culture supernatants, and the reactive oxygen species (ROS) in the cells were also measured by microplate reader. The protein levels of PKC, p-p38 MAPK and HSP70 in the cells were detected by Western blotting.RESULTS: Compared with normal group, the cell viability and beating frequency were decreased in H/R group. LDH and ROS contents, apoptotic rate and p-p38 MAPK level increased significantly (P<0.01). Compared with H/R group, PFC preconditioning increased beating frequency, SOD activity and the protein level of PKC and HSP70, and decreased ROS production, the protein level of p-p38 MAPK and cell apoptotic rate. However, the effect of PFC was inhibited by chelerythrine or SB203580.CONCLUSION: PFC may protect cardiomyocytes from hypoxia/reoxygenation injury. Its mechanism is possibly involved in the inhibition of ROS via increasing the activity of SOD and the activation of PKC, and suppression of excessive activation of p38 MAPK.     

Effects of glycine on intracellular of free calcium and tumor necrosis factor-α of cardiomyocytes during hypoxia/reoxygenation

AIM: To observe the influence of glycine on intracellular free calcium, the concentration of tumor necrosis factor-α and the survival rate of myocardial cells during hypoxia/reoxygenation (H/R). METHODS: The simulated model of myocardial ischemia-reperfusion with the primary cultured cardiomyocytes of neonatal rats was established, and the cultured cardiomyocytes were divided into seven groups, control group, hypoxia/reoxygenation group, glycine (0.5 mmol/L) plus hypoxia/reoxygenation group, glycine (1.0 mmol/L) plus hypoxia/reoxygenation group, glycine (2.0 mmol/L) plus hypoxia/reoxygenation group, glycine (4.0 mmol/L) plus hypoxia/reoxygenation group, 4.0 mmol/L glycine group. RESULTS: Within certain concentration (0.5-2.0 mmol/L), the glycine could inhibit the calcium overload resulting from hypoxia/reoxygenation injury in cells in a dose-dependent manner with the optimal inhibitory effect at 2.0 mmol/L. Glycine inhibited the secretion of tumor necrosis factor-α from myocardial cells and increased the survival rate of myocardial cells. CONCLUSION: Glycine has a protective effect on hypoxia/reoxygenation myocardial cells, which may be related to inhibiting calcium overload and decreasing the production of tumor necrosis factor-α.     

Anti-aging Klotho protein reduce the hypoxia/reoxygenation injury of neonatal rat myocardial cells

AIM: To study the effects of anti-aging Klotho protein on neonatal rat myocardial cells with hypo-xia/reoxygenation (H/R) injury. METHODS: The cardiomyocytes of neonatal SD rats were cultured to establish hypoxia/reoxygenation model. The myocardial cells were divided into normal control group, H/R model group, different concentrations of Klotho protein (0.1 μmol/L, 1 μmol/L and 10 μmol/L) pretreatment groups. The myocardial cells pulse frequency was observed before and after H/R. The cell viability was measured by MTT assay. The leakages of LDH, CK and AST, the content of MDA and the activity of SOD were detected. The apoptotic rate of the myocardial cells was analyzed by flow cytometry. The mRNA expression of endoplasmic reticulum stress markers and apoptosis-related molecules GRP78, CRT, CHOP and caspase-12 was measured by real-time PCR. The protein levels of CHOP, caspase-12 and phosphorylated Akt in the myocardial cells were determined by Western blot. RESULTS: Compared with normal control group, the pulse frequency, cell viability rate and SOD activity of myocardial cells were significantly decreased, the cell apoptotic rate as well as the contents of LDH, CK, AST and MDA were increased in H/R model group. The mRNA expressions of GRP78, CRT, CHOP and caspase-12 as well as the protein levels of CHOP and caspase-12 were increased, whereas p-Akt level was decreased obviously. Compared with H/R model group, the pulse frequency, cell viability rate and SOD activity were increased significantly, the cell apoptotic rate as well as the contents of LDH, CK, AST and MDA were decreased in Klotho pretreated group. The mRNA expression of GRP78, CRT, CHOP and caspase-12 as well as the protein levels of CHOP and caspase-12 were decreased, while p-Akt level increased significantly. CONCLUSION: Anti-aging Klotho protein improves the myocardial cell survival and inhibits the apoptosis by increasing the resistance of the cells to oxidative stress and excessive endoplasmic reticulum stress response, which is related with the activation of Akt phosphorylation in H/R-injured mycardial cells.     

Fuzi polysaccharide protects neonatal rat cardiomyocytes with hypoxia-reoxygenation by inhibiting endoplasmic reticulum stress

AIM: To investigate whether the protection mechanism of Fuzi polysaccharide (FPS) is related to inhibition of endoplasmic reticulum stress in cultured neonatal rat cardiomyocytes with hypoxia/reoxygenation (H/R). METHODS: Cultured rat myocardial cells were divided into control group, H/R group (hypoxia for 3 h and reoxygenation for 6 h) and different concentrations of FPS (0.1 g/L, 1 g/L, 10 g/L or 20 g/L) +H/R groups. The cell survival was detected by MTT assay and cell apoptosis of cardiomyocytes was measured by flow cytometry using Annexin V-FITC staining. The expression of glucose-regulated protein 78 (GRP78), CCAAT/enhancer-binding protein homologous protein (CHOP) and caspase-12 were determined by Western blotting. The mRNA expression of CHOP and caspase-12 was detected by quantitative PCR. RESULTS: After reoxygenation, the expression of GRP78, CHOP and caspase-12 in cardiomyocytes was increased. Compared with H/R group, the expression of GRP78, CHOP and caspase-12 in FPS+H/R groups was significantly inhibited, the survival rate of cardiomyocytes was increased and the apoptosis of cardiomyocytes was inhibited. This protective effect of FPS was in a dose-dependent manner and reached its peak at 10 g/L. CONCLUSION: Fuzi polysaccharide protects cardiomyocytes from H/R injury. The mechanism is related to inhibiting endoplasmic reticulum stress.     

Effect of glycine liposomes on mitochondrial membrane potential and apoptosis in cultured cardiomyocytes

AIM: To observe the effect of glycine liposomes on the mitochondrial membrane potential and the apoptosis rate in cardiomyocytes induced by hypoxia/reoxygenation injury. METHODS: A cardiomyocyte injury model was established by using hypoxia/reoxygenation. DiOC6(3) as fluorescence molecular probe was used to detect the mitochondrial membrane potential in each group. The method of Annexin V associated with PI was used to detect the apoptosis ratio in each group. RESULTS: (1) The result of flow cytometry showed that the mitochondrial membrane potential of cardiomyocytes in H/R group was obviously lower than that in control group (P<0.01). The decrease in mitochondrial membrane potential in Gly-liposome group was the lowest, the percentage of cells about the part of hypofluorescence was (9.61±0.76)%, which was lower than that in glycine group (P<0.01). (2) The apoptosis rate of cardiomyocytes in H/R group was higher than that in control group (20.78±1.58)%,P<0.01. After the treatment of Gly-liposome, the apoptosis rate of cardiomyocytes was lower than that in glycine group (P<0.01). No difference in the apoptosis ratios between blank-liposome group and H/R group was observed(P>0.05).CONCLUSION: Glycine liposomes protect cultured cardiomyocytes against hypoxia/reoxygenation injury. Glycine liposomes produce the better protective effects than glycine.     

p38 MAPK-Pim-3 signal pathway may be involved in cardiomyocyte anoxia preconditioning against anoxia/reoxygenation injury

AIM: To investigate the role of mitogen-activated protein kinases (MAPKs) pathways and the molecular mechanism by which the proto-oncogene Pim-3 protects cardiomyocyte against anoxia/reoxygenation (A/R) injury. METHODS: The primarily cultured neonatal rat ventricular cardiomyocytes were randomly divided into 4 groups: control group; A/R group; APC+A/R group; SB203850, U0126 or SP600125+APC+A/R group. The cells were pre-incubated with U0126 (ERK1/2 inhibitor), SP600125 (SAPK/JNK inhibitor), or SB203850 (p38 MAPK inhibitor) at concentration of 10 μmol/L for 30 min before the APC. The activities of p38 MAPK, JNK and ERK1/2 were detected by Western blotting. The viability of cardiomyocytes was assayed by MTT and the apoptosis of cardiomyocyte was detected by TUNEL. RESULTS: U0126, SB203850, and SP600125 abolished the increased expression of ERK1/2, p38-MAPK, and JNK proteins induced by APC+A/R or A/R, respectively. The expression level of Pim-3 protein significantly decreased when the p38 MAPK signal pathway was inhibited. Meanwhile, the activity of LDH and the apoptosis index increased, and the viability of cardiomyocytes decreased. CONCLUSION: Pim-3 expression through a p38 MAPK signaling pathway may protect cardiomyocytes from A/R injury.     

Effects of acetal hairy holly extractive compound R4 on rat cardiomyocyte injury induced by hypoxia/reoxygenation

AIM: To observe the effects of acetal hairy holly extractive compound R4(AHHECR4) on myocardial cell injury induced by hypoxia/reoxygenation. METHODS: The model of rat myocardial cell injury was induced by hypoxia/reoxygenation. The activity of superoxide dismutase (SOD) in the myocardial cells was measured by the method of xanthine oxidase. The content of malondialdehyde (MDA) was determined by the method of thiobarbituric acid. The activity of dehydrogenase (A) in mitochondria was detected by MTT assay. The activity of lactate dehydrogenase(LDH) and the content of NO in the culture medium were also evaluated. RESULTS: AHHECR4 at concentrations of 5, 10 and 20 μmol/L remarkably increased SOD activity and the value of A, and significantly inhibited MDA production and LDH leakage. Greatly increased content of NO in the culture medium was also observed. CONCLUSION: The results indicate that AHHECR4 has a protective effect on myocardial cells under the condition of hypoxia/reoxygenation injury.     

Preparation of glycine liposomes and it's effect on cardiomyocyte injury induced by hypoxia/reoxygenation

AIM: To prepare glycine liposome microparticle and observe the effect of glycine liposomes on cardiomyocyte injury induced by hypoxia/reoxygenation. METHODS: （1） Reverse-phase evaporation method was used to produce glycine liposomes, the effects of different organic solvents: aether, chloroform and two mixtures of aether/chloroform on entrapment efficiency were evaluated, transmission electron microscope was used to detect the particle diameter of glycine liposomes. （2） A cardiomyocyte injury model was established by using hypoxia/reoxygenation, the activities of lactate dehydrogenase (LDH), creatine kinase (CK) and creatine kinase isoenzyme (CK-MB) of each group were detected. RESULTS: The entrapment efficiency of glycine liposomes prepared with the mixtures of aether/chloroform is highest compared with other organic solvents （64.8％, P<0.01）; all of glycine, glycine liposomes and blank liposomes inhibited the release of LDH, CK and CK-MB induced by hypoxia/reoxygenation in cultured cardiomyocytes, and the inhibition by glycine liposomes was the most obvious （P<0.05，P<0.01）. CONCLUSIONS: The mixtures of aether/chloroform can be used to prepare glycine liposomes, which can get higher entrapment efficiency; glycine liposomes protects cultured cardiomyocytes against hypoxia/reoxygenation-induced injury, and the protective effect of glycine liposomes is better than that of glycine.     

The characteristics of hypertrophic cardiomyocyte injury and the effect of intervention on energy metabolism after different time of hypoxia/reoxygenation

AIM:To investigate the characteristics of pathological injury and its relationship with the transformation of energy metabolism of hypertrophic cardiomyocytes after hypoxia-reoxygenation. METHODS:Cultured rat cardiomyocytes were induced to be hypertrophy by angiotensin Ⅱ (Ang Ⅱ) and norepinephrine (NE). Glucose oxidation rate (GOR), glucolysis rate (GLR) and fatty acid oxidation rate (FOR) were determined by liquid scintillation counting, and cell apoptosis was detected by TUNEL. RESULTS:(1) Compared with the normal cardiomyocytes (NC), the GOR and GLR were slightly higher and the FOR was slightly lower in the group of hypertrophic cardiac cells (HC) than that in the group of normal cardiomyocytes cultured under the normal oxygen partial pressure. The apoptosis rate had no difference between the two groups. (2) The apoptosis rate of hypertrophic cardiomyocytes after hypoxia was significantly higher than that of hypertrophic cardiomyocytes in normal culture. It was higher and moreover, some necrosis cardiomyocytes appeared after reoxygenation. (3) GOR and FOR in both group (NC and HC) were slightly lower in a time-dependent manner after hypoxia than that in each group in normal culture condition. GLR had no difference in both group. The GOR was more lower in both NC and HC group when reoxygenation than that at the point of hypoxia for 2 hours, but the GLR and FOR were significantly higher in HC than that in NC when reoxygenation. (4) The GOR was significantly higher and the GLR and FOR were significantly lower in the hypertrophic cardiomyocytes group (HC) with dichloroacetate (DCA, 1 000 μmol/L) or trimetazidine (TMZ, 1 μmol/L) treated respectively than that in the responded hypertrophic cardiomyocytes after stimulation by hypoxia-reoxygenation. In the meanwhile, the apoptosis rate also was markedly lower in the treated hypertrophic cardiomyocytes group. CONCLUSION:The transformation of energetic metabolism pathway plays an important role in the pathogenesis (mainly the apoptosis) of the hypertrophic cardiomyocytes after hypoxia-reoxygenation.     

Protective effect of quercetin on rat cardiomyocytes against anoxia/reoxygenation injury is mediated by PKCε signaling pathway

AIM：To investigate whether quercetin (Que) protects cardiomyocytes from anoxia/reoxygenation (A/R) injury through protein kinase C epsilon (PKCε) pathway. METHODS：Primary cardiomyocytes were isolated from neonatal SD rats and exposed to A/R (3 h of anoxia followed by 2 h of reoxygenation) as well as Que and/or εV1-2 (a selective PKCε inhibitor) preconditioning. The expression of PKCε in the cells was detected by Western blotting. The levels of lactate dehydrogenase (LDH) and creatine kinase (CK) in cell culture supernatants, the reactive oxygen species (ROS) and mitochondrial membrane potential in the cells, the opening of mitochondrial permeability transition pore (mPTP) and the cell viability and apoptosis were also measured. RESULTS：The expression of PKCε protein was significantly increased in the cardiomyocytes pretreated with 40 μmol/L Que 72 h before A/R (P<0.01 vs A/R group). Meanwhile, Que preconditioning could increase cell survival rate, decrease ROS production and cell apoptosis, alleviate the loss of mitochondrial membrane potential and inhibit the opening of mPTP induced by A/R injury (P<0.01 vs A/R group). However, pretreatment with Que and εV1-2 attenuated these protective effects of Que (P<0.01 vs Que+A/R group). CONCLUSION：One of the mechanisms underlying the cardioprotective effect of Que might be the increase in PKCε protein expression and the activation of its downstream pathway.     

Effects of phytoestrogen α-zearalanol on hypoxia/reoxygenation injury in HUVECs

AIM:To investigate the effects of phytoestrogen α-zearalanol (ZAL) on hypoxia/reoxygenation (H/R) injury and mechanism involved in human umbilical vein endothelial cells (HUVECs). METHODS:HUVECs were exposed to hypoxia for 3 hours and then reoxygenation 1 hour. ZAL or 17β-estradiol (E₂) at concentrations of 10-9-10-6 mol/L were pretreated before hypoxia. The survival rate of HUVECs was detected by MTT. Either the activities of LDH and SOD or the level of MDA in supernatant was detected by spectrophotometry. RESULTS:The survival rate of HUVECs and the activity of SOD were significantly decreased (P<0.01), while the activity of LDH and the level of MDA were significantly increased (P<0.01) after H/R. These changes were reversed by pretreatment with ZAL or E₂, and there was no significant difference between their effects in the same dose of ZAL and E₂. CONCLUSION:These results suggest that phytoestrogen ZAL protects HUVECs from H/R injury by inhibiting the oxidative stress, which was similar to E₂.     

Harmful factors affect glycine receptor α1 subunit mRNA expression in the neonatal rat cardiomyocytes

AIM: To investigate the effects of lipopolysaccharide, hypoxia/reoxygenation,isoproterenol and high concentration of glucose on glycine receptor α₁ subunit mRNA expression in the neonatal rat cardiomyocytes. METHODS: Isolation of cardiomyocytes from Sprague-Dawley rats aging 1～3 d were performed. Cardiomyocytes （1×10⁵～5×10⁵ cells·L^-1）were cultured in DMEM medium containing 15% fetal bovine serum at 37 ℃ in 5%CO₂ atmosphere for 72 h. Then, cultured rat cardiomyocytes were treated with lipopolysaccharide, isoproterenol or high concentration of glucose for 24 h, respectively, or were exposed to hypoxia for 3 h followed by reoxygenation for 3 h. Subsequently, the cell survival rate was measured using CCK-8 reactant and RT-PCR was applied to monitor the expression of glycine receptor α₁ subunit mRNA. RESULTS: Compared with the control group, no significant difference in the cell survival rate was observed （P＞0.05）. The expression of glycine receptor α₁ subunit mRNA was increased （P＜0.01） in lipopolysaccharide（5,10,20,40,80 mg/L）,isoproterenol（20,100,500 μmol/L） or hypoxia/reoxygenation, hypoxia groups, but decreased（P＜0.01）in the group treated with high concentration of glucose（25, 50 mmol/L）. CONCLUSION: Lipopolysaccharide, isoproterenol, hypoxia/reoxygenation or hypoxia upregulates the expression of glycine receptor α₁ subunit mRNA,but high concentration of glucose down-regulates the expression of glycine receptor α₁ subunit mRNA in cultured neonatal rat cardiomyocytes.     

Effects of glucagon-like peptide-1 on myocardial ischemia-reperfusion/hypoxia-reoxygenation injury in rats

AIM: To investigate the effects of glucagon-like peptide-1 (GLP-1) on myocardial ischemia-reperfusion (IR)/hypoxia-reoxygenation (HR) injury in rats. METHODS: Sprague-Dawley rats were randomly divided into 5 groups: sham group, IR group and IR+GLP-1 (0.03 nmol/L, 0.16 nmol/L and 0.30 nmol/L) groups. IR group and IR+GLP-1 group were subject to 30 min of ischemia and 3 h of reperfusion. The myocardial infarct size, the ultrastructural changes of the myocardial tissues, the apoptosis of the cardiomyocytes, the activity of superoxide dismutase (SOD) and the concentration of malondialdehyde (MDA) were detected. Primarily cultured cardiomyocytes were divided into 5 groups at random: control group, HR group and HR+GLP-1 (1 μmol/L, 5 μmol/L and 10 μmol/L) groups. The morphology and apoptosis of the cardiomyocytes were observed. The levels of lactate dehydrogenase (LDH),MDA,SOD,reactive oxygen species (ROS) and mitochondrial membrane potential (MMP) in different groups were detected. RESULTS: Compared with IR group, the myocardial infarct size and cardiomyocyte apoptosis were remarkably reduced, mitochondrial ultrastructures were improved, the activity of SOD was increased and the concentration of MDA was decreased in IR+GLP-1 (0.03 nmol/L, 0.16 nmol/L and 0.30 nmol/L) groups. Compared with HR group, GLP-1 (1 μmol/L, 5 μmol/L and 10 μmol/L) preconditioning significantly decreased the myocardial injury, increased SOD activity, decreased MDA concentration and ROS production, and heightened MMP in a dose-dependent manner. CONCLUSION: GLP-1 protects cardiomyocytes from IR/HR injury, which may be partially due to the effects of anti-oxidative mechanism and the function of mitochondrial protection.     

Effects of adiponectin on reducing endoplasmic reticulum stress injury induced by hypoxia-reoxygenation in cultured rat neonatal cardiomyocytes

AIM: To investigate the effects of adiponectin (APN) on hypoxia-reoxygenation (H/R) induced endoplasmic reticulum stress injury in cultured cardiomyocytes. METHODS: Primary cultured cardiomyocytes were obtained from neonatal rats by enzymatic digestion method. The α-actin expression as molecular marker of the cardiomyocytes was observed by immunocytochemistry. The cells cultured for 72 h were used in the experiment and divided into groups randomly: control group, H/R group, APN+H/R (3 mg/L, 10 mg/L, 20 mg/L, 30 mg/L) groups. The morphological changes of the cardiomyocytes were observed under phase contracted microscope. The content of LDH was measured. The cardiomycocyte apoptosis was detected by flow cytometry. The expression levels of GRP78 and caspase-12 were examined by RT-PCR and Western blotting. RESULTS: The apoptotic rate was significantly increased in H/R group as compared to that in control group (68.20%±1.73% vs 0.73%±0.21%, P<0.05). The levels of LDH in H/R group were also significantly increased. Compared to untreated cells, the protein and mRNA levels of GRP78 and caspase-12 increased significantly in H/R cells. The APN preconditioning significantly reversed these changes. The indexes above improved obviously as compared to H/R group (P<0.05) in a dose-dependent manner. CONCLUSION: Hypoxia/reperfusion induces endoplasmic reticulum stress in rat cardiomyocytes. Adiponectin decreases the endoplasmic reticulum stress injury and plays a protective role by extenuation of cadiomyocyte apoptosis.     

Dendranthema morifolium attenuated the reduction of contraction of isolated heart and cardiomyocytes induced by ischemia/reperfusion

AIM: To investigate the effect of Dendranthema morifolium (Ramat) Tzvel (DM) on isolated rat heart and ventricular myocytes during ischemia/anoxia and reperfusion/reoxygenation.METHODS: The Langendorff perfused rat hearts were used to measure intraventricular pressure and coronary flow. The cell contraction and intracellular calcium transient in enzymatically isolated ventricular myocytes were determined. RESULTS: (1) DM (0.5 g/L) significantly attenuated the inhibitory effects induced by ischemia/reperfusion on left ventricular developed pressure (LVDP), ±dp/dt_max, coronary flow and LVDP×HR, meanwhile increased the content of SOD and decreased the content of MDA in the myocardium; (2) DM (0.5 g/L) attenuated the inhibitory effects of anoxia and reoxygenation on i transient and cell contraction in isolated ventricular myocytes. CONCLUSION: DM attenuated the effects on contractility and intracellular calcium induced by ischemia/anoxia and reperfusion/reoxygenation in the isolated rat heart and the ventricular myocytes. The mechanism might be related to increase in SOD activity and maintaining [Ca]i homeostasis.     

Effect of growth arrest-specific protein 6 on H9c2 cell apoptosis induced by anoxia-reoxygenation via PI3K/Akt survival pathway

AIM: To investigate the effect of growth arrest-specific protein 6(Gas 6) on H9c2 cell apoptosis induced by anoxia-reoxygenation (A/R) and its possible relationship with PI3K/Akt pathway. METHODS: Cultured H9c2 cell line of cardiomyocytes was randomly divided into 4 groups: normal control group, anoxia-reoxygenation group (A/R), anoxia-reoxygenation+Gas6 group (A/R+Gas6) and anoxia/reoxygenation+Gas6+LY294002 group (A/R+Gas6+LY294002). The procedure of A/R was performed in cultured H9c2 cells by 3 h of anoxia and then 3 h of reoxygenation. The viability of the cells and the activity of caspase-3 were detected by automatic biochemistry analytic instrument. Cell apoptotic rates were evaluated by flow cytometry. The protein level of phosphorylated Akt(p-Akt) was determined by Western blotting. RESULTS: Compared with control group, the cell viability was significantly decreased, and caspase-3 activity, cell apoptotic rate and the protein level of p-Akt were increased in A/R group. Compared with A/R group, the caspase-3 activity and cell apoptotic rate reduced markedly, while the cell viability and the protein level of p-Akt were significantly increased in A/R+Gas6 group .The effect of Gas6 was inhibited by LY294002. CONCLUSION: Gas6 may protect the H9c2 cells from anoxia-reoxygenation-induced apoptosis. Its mechanism is possibly involved in the activation of PI3K/Akt survival pathway via increasing the phosphorylation of Akt protein.     

Effects of adiponectin against hydrogen peroxide induced myocardial injury in cultured rat neonatal cardiomyocytes

AIM: To observe the effects of adiponectin on injury of the 3-4 d SD rat cardiomyocytes induced by the intervention of H2O2. METHODS: Primary cardiomyocytes were obtained from neonatal rat and were cultured by enzymatic digestion methods. The molecular marker was observed by α-actin immunocytochemistry. Primary cultured 3-4 d cells were used in experiment, and the injury model was established by H2O2, and adiponectin and Ara-A were used for pre-treatment before cell culture. The morphological change of cardiomyocytes was observed under electron microscope. The contents of LDH, MDA and the activity of SOD were measured. The apoptosis of cardiomyocytes was detected by agarose gel electrophoresis and Annexin V/PI staining with flow cytometry. RESULTS: Adiponectin pretreatment significantly decreased the release of LDH（P<0.05）and the content of MDA (P<0.05), and increased the activity of SOD (P<0.05) as compared to H2O2 injury group. The brightness of DNA ladder attenuated and the rate of apoptosis also decreased (P<0.05) compared to H2O2 injury group. Ara-A (1 mmol/L) blocked the protection of adiponectin partly.CONCLUSION: H2O2 induces the injury and apoptosis of cardiomyocytes. The protective effect of adiponectin is through AMPK pathway.