Effects of transplantation of adipose stromal vascular fraction on cardiac function in adriamycin-induced heart failure rats

AIM: To investigate the effects of transplantation of adipose stromal vascular fraction (SVF) on the cardiac function in adriamycin-induced heart failure rats. METHODS: SVF was isolated from adipose tissue of a Sprague-Dawley (SD) rat by collagenase digestion and marked with green fluorescent protein (GFP) in vitro. Twenty-eight SD rats were randomized into normal control group (n=8), adriamycin control group (n=10) and SVF treatment group (n=10). Adriamycin at dose of 15 mg/kg was intraperitoneally injected into the rats twice a week for 4 weeks to induce heart failure. SVF cells (05 mL, 1×107/L) were injected via penis vein, and PBS vehicle was injected into the control animals in the same way. Four weeks later, the cardiac function was determined by multichannel physiologic recorder via cardiac catheterization. SVF was demonstrated in the myocardium by frozen section fluorescence microscopy. The CD31 expression was determined by an immunohistochemical test. RESULTS: Compared with adriamycin control group, SVF transplantation increased left ventricular peak systolic pressure ［LVSP, （13565±21.58) mmHg vs (10558±2262) mmHg, P<005］, left ventricular pressure maximal rise rate ［+dp/dtmax, (4 81565±56624) mmHg/s vs (3 53550±46528) mmHg/s, P<005］, and left ventricular pressure maximal decline rate ［-dp/dtmax, (3 67756±46775) mmHg/s vs (2 73865±51251) mmHg/s, P<005］. The results of the CD31 immunohistochemical test showed that the nuclear staining and granule distribution were more uniform, and the number of blood vessels per visual field increased in SVF treatment group as compared with adriamycin control group (P<005). CONCLUSION: SVF transplantation improves the cardiac function in the rat model of heart failure, possibly and partly through the promotion of myocardial neovascularization.     

Effects of site-specific antibody of Na+-Ca2+ exchanger on isolated rat heart functions/vascular tone and comparison with ouabain and (±)Bay K8644

AIM：To investigate the effects of site-specific (α-1 repeat: 124HNFTAGDLGPSTIVGSAAFNMF145) antibody of Na+-Ca2+ exchanger (NCX) on the isolated rat heart functions and vascular tone and to compare them with the effects of Na+-K+ pump inhibitor ouabain and L-type Ca2+ channel agonist (±)Bay K8644. METHODS：The heart and thoracic aorta were rapidly isolated from the adult rats weighing 250～300 g. The hemodynamic indexes including left ventricular developed pressure, maximal rate of rise/decline of left ventricular pressure (±dp/dtmax) and coronary resistance were observed by Langendorff isolated heart perfusion system. The rings of thoracic aorta were mounted into the organ baths and the vascular tone was determined. RESULTS：At concentrations of 10, 20 and 40 nmol/L, the site-specific antibody of NCX enhanced the cardiac functions in a dose-dependent manner during the perfusion period with no arrhythmia. At the same time, it did not increase the coronary resistance. The antibody had no effect on the vascular tone of isolated thoracic aorta ring at the same concentrations. Ouabain at concnentration of 0.5 mmol/L and (±)Bay K8644 at concentration of 01 mmol/L had similar effects with the site-specific antibody of NCX at concentration of 40 nmol/L on left ventricular developed pressure and +dp/dtmax of isolated rat hearts during perfusion, but (±)Bay K8644 (01 mmol/L) didn’t have significant effect on -dp/dtmax. Ouabain (0.5 mmol/L) even reduced -dp/dtmax as compared with the control. After administration of ouabain (0.5 mmol/L) for 5 min, most isolated hearts appeared premature pulse more than 5 beats/min. (±)Bay K8644 (0.1 mmol/L) did not induce arrhythmia during all the time of exposure. CONCLUSION: The site-specific (α-1 repeat: 124HNFTAGDLGPSTIVGSAAFNMF145) antibody of NCX enhances both systolic and diastolic functions of isolated rat hearts without arrhythmia. Meanwhile, this antibody doesn’t increase coronary resistance during perfusion and vascular tone in isolated thoracic aorta rings.     

Effects of stretch on transient outward potassium and inward rectifier potassium current in cultured neonatal rat atrial myocytes

AIM：To investigate the effects of mechanical stretch on transient outward potassium current (Ito), inward rectifier potassium current (IK1) and action potential duration(APD) of cultured neonatal rat atrial myocytes. METHODS：Neonatal rat atrial myocytes were isolated and cultured on silicone sheeting with or without stretch for 24 h. The silicone membrane area was increased by 12% in stretched group. The cells without stretch served as control. Ito, IK1 and APD were recorded by the technique of whole-cell patch clamp. RESULTS：Compared with control group, Ito density in stretched myocytes was significantly reduced ［(16±04) pA/pF vs (121±29) pA/pF, P<001］, whereas IK1 density was increased ［(-108±08) pA/pF vs (-88±09) pA/pF, P<001］. The APDs at 50% and 90% levels of repolarization (APD50 and APD90) in the stretched cells were obviously decreased than those in non-stretched cells ［(105±14) ms vs (155±24) ms, (300±28) ms vs (563±36) ms, P<001］. CONCLUSION：Stretch stimulation leads to the reduction of Ito density, the increase in IK1 density and the shortness of APD in cultured rat atrial neonatal myocytes, which may contribute to atrial electrical remodeling induced by pressure overload.     

Relationship between 3-nitrotyrosine and myocardial cell apoptosis in rat diabetic cardiomyopathy

AIM: To explore the relationship between 3-nitrotyrosine (3-NT) level in hearts or blood and myocardial cell apoptosis in rat diabetic cardiomyopathy (DCM). METHODS: Sixty Sprague-Dawley (SD) rats (male, 8-week-old) were randomly divided into 4 groups: normal group, diabetic cardiomyopathy group (DCM group), diabetic rats treated with valsartan (40 mg·kg^-1·d^-1, D+V group) and DCM rats treated with valsartan (40 mg·kg^-1·d^-1, DCM+V group). Apoptotic index (AI) of rat cardiac myocytes was examined by TUNEL. The expression index (EI) of 3-NT in rat cardiac myocytes was examined by immunohistochemistry. The 3-NT concentration in rat serum was examined by ELISA. RESULTS: (1) Significant differences of the heart weight indexes among the 4 groups were observed (P<0.01). The heart weight indexes in DCM group and DCM+V group were higher than those in normal group and D+V group (P<0.01). (2) The EI of 3-NT in the cardiac myocytes was positively correlated with the AI of the cardiac myocytes in the same group (P<0.01), but the concentration of 3-NT in blood had no correlation with the AI of cardiac myocytes (P>0.05). (3) The difference of AI of cardiac myocytes among the 4 groups had statistical significance (P<0.01). The arrangement from high to low of AI was DCM group > D+V group and DCM+V group > N group (P<0.05). (4) The EI of 3-NT in DCM group was the highest as compared to other groups (P<0.05). (5) No statistical difference of 3-NT concentration in blood among the 4 groups was observed (P>0.05). CONCLUSION: (1) The expression of 3-NT in DCM myocardial tissues in SD rats is significantly increased and closely correlated with the apoptosis in myocardial cells. Valsartan inhibits 3-NT expression in DCM myocardial cells, thus inhibits the DCM myocardium apoptosis. (2) The 3-NT level in blood can not be true for reflection of 3-NT expression in DCM myocardial tissues and its effect on myocardial cell apoptosis.     

Change of L-type voltage-gated Ca2+ channel current during focal brain ischemia in diabetic rats

AIM: To observe the change of L-type voltage-gated Ca²⁺ channel current during focal brain ischemia in the normal rats and the rats with diabetes mellitus (DM). METHODS: Combination of high-fat diet with streptozotocin (STZ) was used to establish DM animal model. The operation of middle cerebral artery occlusion (MCAO) with monofilament on the rats was performed. The animals were divided into sham operation group, MCAO 1 h group, MCAO 3 h group, MCAO 6 h group, MCAO 24 h group, DM sham operation group, DM+MCAO 1 h group, DM+MCAO 3 h group, DM+MCAO 6 h group and DM+MCAO 24 h group. The score of neural function was determined to judge the degree of palsy in the rats in MCAO 24 h group and DM+MCAO 24 h group. The changes of L-type voltage-gated Ca²⁺ channel current of cortex neurons during ischemia were measured using the whole-cell patch clamp technique. RESULTS: The rats in DM+MCAO 24 h group awaked slowly, and the degree of semiplegia was more serious than that in the rats in MCAO 24 h group. The score of neural function in DM+MCAO group was higher than that in MCAO group (P<0.05). The longer the ischemic time was, the higher L-type voltage-gated Ca²⁺ channel current was observed in MCAO group and DM+MCAO group (P<0.05). L-type voltage-gated Ca²⁺ channel current in DM+MCAO group was higher than that in MCAO group at each time point(P<0.05). CONCLUSION: The aggratation of ischemic injury during DM+MCAO is probably associated with Ca²⁺ overload induced by calcium channel opening and current increasing.     

Effects of Kv1.5 on proliferation and apoptosis of rat PASMCs under hypoxia+hypercapnia condition and relationship with MAPK pathway

AIM：To investigate the effects of voltage-dependent K＋ channel 1.5 (Kv1.5) on the proliferation and apoptosis of rat pulmonary artery smooth muscle cells (PASMCs) under hypoxia+hypercapnia condition and the relationship with mitogen-activated protein kinase(MAPK) signal pathway. METHODS：The PASMCs isolated from the male SD rat were cultured under hypoxia+hypercapnia condition, and randomly divided into normal group (N group), hypoxia+hypercapnia group (HH group), hypoxia+hypercapnia+DMSO incubation group (HD group), hypoxia+hypercapnia+U0126 (an extracellular signal-regulated kinase 1/2 inhibitor) incubation group (HU group), hypoxia+hypercapnia+SB203580 (a p38 mitogen-activated protein kinase inhibitor) incubation group (HS group), and hypoxia+hypercapnia+anisomycin (an agonist of MAPK) incubation group (HA group). Cell Counting Kit-8 was used to detect the cell viability. The protein expression of Kv1.5, PCNA and Bax was detected by Western blotting. RESULTS：Compared with N group, the cell viability and PCNA protein expression in HH group and HD group were significantly raised (P<001), but Kv1.5 and Bax proteins were significantly decreased (P<0.01). No difference between HH group and HD group was observed (P>005). Compared with HD group, the cell viability and PCNA protein expression in HU group, HS group and HA group were decreased (P<0.05 or P<0.01), but Kv1.5 protein and Bax protein were raised (P<0.01), with the most significant changes in HA group. ^{CONCLUSION：}The regulation of Kv1.5 to the proliferation and apoptosis of PASMCs under hypoxia+hypercapnia condition might have a relationship with the activation of MAPK signal pathway.     

Role of endoplasmic reticulum stress in Bim-mediated cardiomyocyte apoptosis induced by hypoxia

AIM:To investigate the role of endoplasmic reticulum stress (ERS) in the process of Bim-mediated cardiomyocyte apoptosis induced by hypoxia. METHODS:Cardiomyocytes were isolated from neonatal Sprague-Dawley rats aged 1~3 days, and primarily cultured in vitro. The antibody targeting α-striated muscle actin was used to identify the cardiomyocytes. The siRNAs targeting bim were transfected into cardiomyocytes with liposome, followed by detecting the expression of Bim by Western blotting. Cardiomyocytes were divided into five groups: blank control group, hypoxia group, hypoxia+liposome group, hypoxia+negative control siRNA group and hypoxia+Bim-siRNA group. The cell viability was determined by MTT assay, and the cell apoptotic rate and the intracellular calcium concentration were measured by flow cytometry. The protein expression of caspase-12 and inositol 1,4,5-triphosphate (IP3) was detected by Western blotting. RESULTS:Immunohistochemical identification confirmed that rat cardiomyocytes were successfully cultured. Green fluorescence was observed in the cells transfected with negative control siRNA under fluorescence microscope. The expression of Bim was obviously inhibited after transfected with Bim-siRNAs and the silencing efficiency of Bim-siRNA-2 was the highest (86.73%). Compared with blank control group, the viability of cardiomyocytes in hypoxia group was significantly reduced (P<005). Compared with hypoxia+negative control siRNA group, the viability of cardiomyocytes in hypoxia+Bim-siRNA group was significantly increased (P<005). The apoptotic rate and the intracellular calcium concentration of cardiomyocytes were obviously increased in hypoxia group (P<0.01), and were both decreased after bim silencing (P<005 or P<0.01). The expression of caspase-12 and IP3 was up-regulated in hypoxia group (P<005), and was down-regulated after bim silencing (P<005 or P<0.01). CONCLUSION: Cardiomyocyte apoptosis induced by hypoxia can be inhibited by silencing the expression of bim gene. Caspase-12 and IP3, as markers of ERS, may participate in the process of Bim-mediated cardiomyocyte apoptosis induced by hypoxia.     

Mechanisms of hyperglycemia induced by immunosuppressant FK506

AIM：To investigate the effect of immunosuppressant FK506 on serum glucose in rats and to explore its mechanism. METHODS：Sprague-Dawley rats (n=12) were randomly divided into drug group and normal group. The rats in drug group were intraperitoneally injected with FK506 at dose of 1 mg·kg-1·d-1 and the rats in normal group received saline (1 mL·kg-1·d-1, ip) for 14 d. The fasting weight and fasting glucose were regularly measured every 2 d. Visceral fat was isolated from the rats at the end of experiment. The mRNA expression of adiponectin, leptin, visfatin, resistin, retinol-binding protein 4 (RBP4) and peroxisome proliferator-activated receptors γ (PPAR-γ) was determined by real-time fluorescence quantitative PCR. The protein expression of PPAR-γ and adiponectin was measured by Western blotting. RESULTS：Compared with normal group, the concentration of fasting blood glucose in model group was significantly increased from the 10th day (P<0.05). At day 14, the fasting blood glucose of the model group increased from (5.10±062) mmol/L to (7.73 ± 0.73) mmol/L. No significant change of blood glucose in normal group between the 10th day and the 14th day ［from (4.66 ± 0.32) mmol/L to (5.80±0.10) mmol/L］ was observed. Compared with normal group, the mRNA expression of PPAR-γ, adiponectin and leptin in the adipose tissue of model group was significantly decreased (P<001), whereas the expression of visfatin, resistin and RBP4 was significantly increased (P<005). Compared with normal group, the expression of PPAR-γ and adiponectin in model group was decreased (P<001). CONCLUSION：FK506 may decrease the expression of PPAR-γ to change the expression of adipocytokines and induce hyperglycemia in rats.     

Effects of metoprolol on phosphorylated connexin 43 expression in myocardial tissues and apoptosis of myocardial cells in heart failure rats

AIM：To explore the in vivo effects of metoprolol on the expression of phosphorylated connexin 43 (p-Cx43) in myocardial tissues and the apoptosis of myocardial cells in rats with heart failure (HF).METHODS：One hundred Sprague-Dawley rats were randomly divided into 5 groups (each n=20): sham group, HF group, low-dose (1.25 mg·kg-1·d-1) metoprolol treatment (MetoA) group, middle-dose (5 mg·kg-1·d-1) metoprolol treatment (MetoB) group and high-dose (20 mg·kg-1·d-1) metoprolol treatment (MetoC) group.The rats in HF group and metoprolol treatment groups were subject to abdominal aortic ligation, and different doses of metoprolol were given 4 weeks later till 8 weeks after operation.Echocardiography was conducted to monitor the hemodynamic parameters at the 4th and 8th weeks, and the rat hearts were taken at the 8th week after operation.The morphological changes and the proliferation of collagen fibers in myocardial tissues were observed by HE and Masson staining, respectively.The expression level of p-Cx43 was detected by Western blotting and the apoptosis of myocardial cells was assessed by TUNEL method.The relationship between p-Cx43 expression level and apoptotic index was analyzed by Pearson’s correlation.RESULTS：(1) Echocardiography showed that metoprolol could effectively improved cardiac hemodynamics in HF rats, and pathological findings suggested that metoprolol could effectively reverse HF-induced cardiac remodeling in a dose-dependent manner within the therapeutic dose range.(2) Western blotting showed that p-Cx43 expression in HF group was significantly higher than that in sham group (P<001), and that in all metoprolol treatment groups was significantly decreased compared with HF group (P<005 or P<001), among which pairwise comparisons also showed significant differences (P<001).(3) The myocardial apoptotic index in HF group ［(51.17±6.94)%］ was significantly increased compared with sham group ［(4.62±160)%, P<001］.Compared with HF group, myocardial apoptotic indexes in MetoA group ［(40.60±4.15)%］, MetoB group ［(30.66±4.00)%］ and MetoC group ［(22.24±5.69)%］ were significantly decreased (P<001), among which pairwise comparisons also showed significant differences (P<001).(4) The expression level of p-Cx43 was positively correlated with the apoptotic index (r=0.905, P<001).CONCLUSION: The mechanism of metoprolol against HF-induced myocardial apoptosis may be related to inhibition of p-Cx43 expression.     

Effect of autophagy on L-type calcium channel current induced by gp120V3 in hippocampus neurons

AIM: To observe the influence of autophagy on L-type calcium channel current induced by gp120V3 loop in hippocampal neurons.METHODS: Hippocampal neurons were exteriorized from the newborn rats within 1 d and primarily cultured for 7 d. The neurons were divided into 2 parallel groups, namely control group, gp120V3 group, autophagy inhibitor 3-MA group, gp120V3 + 3-MA group; control group, gp120V3 group, autophagy activator rapamycin group, gp120V3 + rapamycin group. Whole-cell pathch-clamp was used to record L-type calcium channel current. RESULTS: Compared with control group, the density of L-type calcium channel current increased in gp120V3 group and 3-MA group(P<0.05). Compared with gp120V3 group, the density of L-type calcium channel current increased in gp120V3 + 3-MA group(P<0.05). Compared with control group, the density of L-type calcium channel current decreased in rapamycin group(P<0.05). Compared with gp120V3 group, the density of L-type calcium channel current increased in gp120V3 + rapamycin group(P<0.05).CONCLUSION: Autophagy may be involved in the gp120V3 loop-mediated L-type calcium channels in hippocampus neurons.     

新书推荐：《分子克隆实验指南》（第三版）

AIM: To study the effect of panax notoginseng sponins (PNS) on L-type Ca²⁺ current in isolated right ventricle myocytes from chronic hypoxic rats. METHODS: Using whole cell patch clamp recording technique,we measured I_Ca-L in isolated right ventricle myocytes which were divided into three group:control group, chronic hy-poxic group and chronic hypoxic group with PNS(100 mg·kg^-1·d^-1). RESULTS: The result showed I_Ca-L of cells from chronic hypoxic group were significantly larger than the other two groups(P＜0.05). CONCLUSION: PNS decreases L-type Ca²⁺ current of the right ventricle myocytes from chronic hypoxic rats.     

Metoprolol inhibits norepinephrine-induced rat cardiomyocyte apoptosis and connexin 43 phosphorylation

AIM: To study the effects of metoprolol (Meto) on the apoptosis of neonatal rat cardiomyocytes and the phosphorylation of connexin 43 (Cx43) induced by norepinephrine (NE). METHODS: Neonatal SD rat cardiomyocytes were divided into the following five groups (n=6 in each group): (1) control (Con) group: no treatment; (2) NE group: treatment with NE at 0.1 μmol/L for 24 h; (3) NE+Meto group: simultaneous treatment with NE and Meto both at 01 μmol/L for 24 h; (4) NE+Meto+PD98059 group: pretreatment with extracellular signal-regulated kinase (ERK) phosphorylation inhibitor PD98059 at 10 μmol/L for 30 min and then treatment with NE and Meto both at 01 μmol/L for 24 h; (5) NE+PD98059 group: pretreatment with PD98059 at 10 μmol/L for 30 min and then treatment with NE at 01 μmol/L for 24 h. The beating rates of cardiomyocytes in various groups were calculated, and the viability of cardiomyocytes was assayed by MTT method. The Cx43 mRNA expression was detected by RT-PCR, and the protein expression of phosphorylated Cx43 (p-Cx43), phosphorylated ERK1/2 (p-ERK1/2) and cleaved caspase-3 was detected by Western blotting. RESULTS: (1) Separate NE treatment could significantly increased the beating rate of cardiomyocytes and reduced cell viability, while Meto showed the opposite effects. PD98059 treatment had no significant effect on cardiomyocyte beating rate, but suppressed Meto to improve cell viability to some extent. (2) Compared with Con group, separate NE treatment significantly increased the Cx43 mRNA expression (P<001). Compared with NE group, Meto or PD98059 intervention could significantly inhibited Cx43 mRNA expression (both P<001), and simultaneous treatment with Meto and PD98059 could further suppress Cx43 mRNA expression up-regulated by NE (P<001). (3) Compared with NE group, Meto significantly inhibited the increased p-Cx43, p-ERK1/2 and cleaved caspase-3 expression induced by NE (P<001), and simultaneous treatment with Meto and PD98059 could further enhance the inhibition of p-Cx43, p-ERK1/2 and cleaved caspase-3 expression by Meto (P<001). PD98059 treatment had no significant effect on the increased p-Cx43 and cleaved caspase-3 expression induced by NE (P>005). CONCLUSION: The inhibitory effect of Meto on NE-induced cardiomyocyte apoptosis is related to the inhibition of Cx43 phosphorylation, which may be partly mediated via ERK1/2 pathway.     

Combinational effects of trimetazidin and parecoxib on acute myocardial infarction in rats

AIM: To investigate the protective effects and mechanisms of combinational use of trimetazidine(TMZ) and parecoxib sodium on acute myocardial infarction (AMI) in rats. METHODS: Sixty-six Sprague-Dawley rats were randomly divided into 5 groups: sham group; AMI group; AMI+TMZ group; AMI+parecoxib group; AMI+TMZ+parecoxib group. All rats were sacrificed and cardiac functions (HR, LVSP, LVEDP, +dp/dt_max,-dp/dt_max) were measured with a Pclab-3804 biological signal processing system on the 8th day. The infarct size in each group was checked up by TTC staining method. RT-PCR was employed to detect the bax mRNA and bcl-2 mRNA. The protein levels of COX-2, Bax, Bcl-2 and cleaved caspase-3 in myocardium were determined by Western blotting. The activity of caspase-3 in each group was measured by colorimetric assay kit, and the apoptotic rates were detected with DNA ladder kit.RESULTS: Compared with sham group, increased expression of COX-2 protein (P<0.01) was observed in AMI group. The expression of COX-2 protein in parecoxib group was lower than that in AMI group (P<0.01). Compared with AMI group, the combinational use of trimetazidin and parecoxib improved contractile functions (LVSP and +dp/dt_max), reduced the infarct size and lowered the apoptotic rates remarkably. Specifically, the combinational use of trimetazidin and parecoxib showed better effects than use of trimetazidin or parecoxib alone. Reduced expression of Bax/Bcl-2 mRNA and protein, the reduced caspase-3 activity and cleaved caspase-3 expression were also found in combinational group as compared with other groups (P<0.05).CONCLUSION: The combinational use of trimetazidin and parecoxib effectively improves cardiac functions and reduces infarct size. The mechanism of the protective effect is probably associated with inhibiting apoptosis of cardiac myocytes.     

Effect of garlicin on sodium channel current in rat ventricular myocytes

AIM: To observe the effect of garlicin on sodium channel(I_Na) in isolated ventricular myocytes of rats. METHODS: The ventricular myocytes of rats were obtained by enzymatic dissociation and treated with different concentrations of garlicin. The change of I_Na was recorded by the technique of whole-cell patch clamp recording.RESULTS: Garlicin decreased the I_Na of isolated ventricular myocytes in a dose- and voltage-dependent manner. The current density was elevated to peak under the condition that the membrane voltage was -40 mV before treated with garlicin. The current density was decreased by 48% from peak after treated with 500 μmol/L garlicin . No significant change of the active curve with the use of garlicin was observed. The median inactive voltages of the inactive curves before and after garlicin treatment were (-88.61±9.60) mV and (-103.03±8.90) mV (P<0.01), respectively, and the slopes were -7.85±0.88 and -7.55±2.75 (P>0.05), respectively, indicating that garlicin made a shift to the negative direction. CONCLUSION: Garlicin treatment induced the current density-voltage curve of I_Na to shift up and significantly decreased the current density. The inactive curve of sodium channel moved to the left, while the current density was not decreased after treated with garlicin. Garlicin blocks sodium channel in its inactive state in a dose- and voltage-dependent manner.     

Effect of β3-adrenoceptor activation on ventricle fibrillation threshold and effective refractory period in rats with heart failure

AIM: To observe the effect of β₃-adrenoceptor (AR) on ventricle fibrillation threshold (VFT) and effective refractory period (ERP) in rats with heart failure.METHODS: Rats were randomized into control group and heart failure group. The expression of β₃- AR mRNA was detected with RT-PCR. The VFT, ERP, left ventricle end-systolic pressure(LVESP)，left ventricle end-diastolic pressure(LVEDP), +dp/dtmax and -dp/dtmax were measured at the same time with administration of BRL37344 (β₃-AR agonist).RESULTS: ① Both the expression of β₃-AR mRNA and the proportion (β₃/β₁+β₂+β₃) were increased in failure rats comparied with those in control rats (0.028 vs 0.011 and 5.4% vs 1.2%, P<0.05). ② ERP was longer in rats with heart failure than that in control group (70.5 ms±5.5 ms vs 59.5 ms±6.4 ms, P<0.05). No difference in ERP in rats with heart failure was observed before and after administration of BRL37344 (73.0 ms±4.8 ms vs 70.5 ms±5.5 ms, P>0.05). ③ VFT was lower in rats with heart failure than that in control group (10.9 mV±0.8 mV vs 30.5 mV±1.3 mV, P<0.05) and decreased obviously in rats with heart failure after administration of BRL37344 (7.1 mV±0.6 mV vs 10.9 mV±0.8 mV, P<0.05). The decrease in VFT correlated with the effect of LVESP, +dp/dtmax, -dp/dtmax with BRL37344 and the expression of β₃-AR mRNA (correlation coefficient: 0.788, 0.708, 0.759, 0.787; P<0.05). CONCLUSION: The expression of β₃-AR mRNA in left ventricle is obviously increased in rats with heart failure. The activation of β₃-AR has no effect on ERP but can decrease VFT which correlates with the effect of β₃-AR on LVESP, +dp/dtmax, -dp/dtmax and the expression of β₃-AR mRNA.     

S100A6 promotes proliferation and migration of human osteosarcoma cell line 143B through PI3K/Akt signaling pathway

AIM: To investigate the effect of PI3K/Akt signaling pathway on S100A6-induced proliferation and migration of human osteosarcoma cell line 143B. METHODS: Recombinant human S100A6 protein (rhS100A6) was prepared. The 143B cells were treated with rhS100A6 in the presence or absence of PI3K inhibitor (LY294002 or wortmannin) exposure. The final concentrations of rhS100A6, LY294002 and wortmannin were 30 mg/L, 10 μmol/L and 0.5 μmol/L, respectively. The expression levels of total Akt (t-Akt) and phosphorylated Akt (p-Akt) in the 143B cells were analyzed by Western blotting. The cell proliferation and migration were determined by MTT and Transwell assays. RESULTS: rhS100A6 protein was successfully prepared, and significantly increased the proliferation and migration of 143B cells (P<005). rhS100A6 up-regulated the phosphorylation of Akt in 143B cells (P<005). Compared with rhS100A6 group, the level of p-Akt in 143B cells and the proliferation and migration of the cells were decreased in combined treatment group of rhS100A6 with LY294002 or wortmannin (P<005), where the proliferation rate at different time points dropped from 10.3% to 69.7% (P<005), and the migration rate dropped from 34.9% to 47.7% (P<005). CONCLUSION: To some extent, S100A6 promotes proliferation and migration of human ostersarcoma cell line 143B through PI3K/Akt signaling pathway.     

Protein kinase A regulates small-conductance calcium-activated potassium type 2 channel in chronic atrial fibrillation patients

AIM：To investigate the alteration of small-conductance calcium-activated potassium type 2 (SK2) channel currents in atrial myocytes from atrial fibrillation (AF) patients, and the relationship between protein kinase A (PKA) and SK2 channel. METHODS：Right auricular tissues were obtained from the patients undergoing open-heart surgery with extracorporeal circulation. Single atrial myocytes were isolated by modified enzymatic dissociation method. The SK2 channel currents in the isolated human atrial myocytes were recorded using whole-cell patch-clamp technique. The alteration of SK2 channel currents and the regulation of SK2 channel by PKA were compared between sinus rhythm (SR) group and AF group. The total protein and PKA levels in human atrial tissues were detected by BCA assay and ELISA, respectively. RESULTS：The SK2 channel current densities and the proportion of SK2 channel currents in the integrated inward currents were significantly increased in AF group (all P<0.05 vs SR group). PKA-selective inhibitor H-89 reduced SK2 channel current densities and the proportion of SK2 channel currents in the integrated inward currents in both SR and AF groups, with larger reduction in AF group (all P<0.05 vs SR group). The PKA level was significantly decreased in AF atrial tissues (P<0.05 vs SR group). CONCLUSION: The increase in SK2 channel currents underlies the occurrence and maintenance of AF. PKA-dependent regulation may be involved in the remodeling of SK2 channel in both SR and AF human atrial myocytes, with a more powerful effect in AF.     

Expression of GATA3 in human breast cancer tissues and its clinical significance

AIM: To investigate the expression of GATA3 in human breast carcinoma and its clinical significance. METHODS: The expression level of GATA3 in breast cancer tissues from 124 patients was detected by the method of immunohistochemistry and the relationships between GATA3 expression and other clinicopathological factors were analyzed. RESULTS: Low expression of GATA3 in breast cancer tissues was associated with estrogen receptor (ER)/progesterone receptor (PR) negative, high histological tumor grade, p53 mutation and vascular invasion (P<005), but not with age, tumor size,human epidermal growth factor receptor 2 (HER-2) expression and lymph node metastasis (P>005). In all breast cancer tissues, the positive expression rate of GATA3 was 56.4%. The positive expression rate of GATA3 in luminal breast cancer is 684%, higher than that in non-luminal breast cancer (326%, P<005). In all breast cancer tissues, the expression of GATA3 in middle recurrence risk group was higher than that in high recurrence risk group (P<005). CONCLUSION: GATA3 expression in breast cancer is related to differentiation and biological characteristics of the tumor, which can be a factor for evaluation of the treatment and prognosis.     

Effect of simvastatin on function of mouse pancreatic beta cells and its mechanisms

AIM: To observe the influence of simvastatin on insulin secretion function of mouse pancreatic beta cell line MIN6 and to explore its possible mechanisms.
METHODS: MIN6 cells were randomly divided into normal control group and low-, middle-and high-concentration simvastatin treatment groups, which were cultured for 48 h with high-glucose DMEM containing 15% fetal bovine serum plus 0, 2, 5 and 10 μmol/L simvastatin, respectively. The insulin secretion of MIN6 cells was measured by radioimmunoassay. The content of ATP in MIN6 cells was measured by biochemiluminescence method. The mRNA and protein expression levels of inwardly rectifying potassium channel 6.2 (Kir6.2), voltage-dependent calcium channel 1.2 (CaV1.2) and glucose transporter 2 (GLUT2) were detected by real-time fluorescence quantitative PCR and Western blotting, respectively.
RESULTS: Compared with normal control group, middle-and high-concentration simvastatin treatment markedly decreased the synthesis and secretion of insulin in MIN6 cells (P<005). The content of ATP in MIN6 cells was markedly decreased in simvastatin treatment groups (P<005). The mRNA expression level of Kir6.2 in MIN6 cells was significantly up-regulated in simvastatin treatment groups (P<001), while the mRNA expression levels of CaV1.2 and GLUT2 were significantly down-regulated in middle-and high-concentration simvastatin treatment groups (P<001). The protein expression of Kir6.2 was significantly increased but that of CaV1.2 was significantly decreased in middle-and high-concentration simvastatin treatment groups (P<001), and the protein expression level of GLUT2 was markedly decreased in high-concentration simvastatin treatment group (P<001).
CONCLUSION: Simvastatin inhibits insulin synthesis and secretion in mouse pancreatic beta cell line MIN6 via suppressing ATP production, up-regulating the expression of Kir6.2 and down-regulating the expression of CaV1.2 and GLUT2.     

Valsartan protects a rat model of adriamycin-induced dilated cardiomyopathy from left ventricular remodeling and failure

AIM: To investigate whether and how AT1 receptor blocker， valsartan， attenuates left ventricular remodeling and failure in a rat model of adriamycin（ADR）-induced dilated cardiomyopathy. METHODS: Weight-matched adult male Wistar rats were randomly divided into 3 groups as follows: 1) the ADR group, in which 2.5 mg/kg of ADR was weekly injected via a tail vein for 10 weeks (n=25); 2) concomitant AT1 receptor blocker valsartan and ADR, in which valsartan was administered by daily gavage at a dose of 30 mg·kg-1·d-1 (n=10); 3) control group (n=10). Hemodynamics and echocardiographic measurements were obtained at 12 weeks after treatment. Finally, left ventricle (LV) samples were collected at 12 weeks. The hydroxyproline content was determined by the methods of chloramines T. The expression of MMP-2, MMP-9 and tissue inhibitors of metalloproteinase-1 (TIMP-1) were measured by Western blotting. MMP-2 and -9 gelatinolytic activities were measured by gelatin zymography. RESULTS: Mortality was significantly lower in valsartan -treated rats than that in ADR rats (20% versus 40%, P<0.01). The dilatation of LV cavity was significantly attenuated in ADR-induced dilated cardiomyopathy rats given valsartan. Valsartan partially normalized LV contractile function, which was significantly reduced in ADR rats. The hydroxyproline content was increased in ADR-DCM group and significantly reduced by valsartan treatment (P<0.01). The protein levels of LV MMP-2 and MMP-9 were increased in ADR rats and attenuated by valsartan treatment (both P<0.01). However, no change in TIMP-1 was observed (P>0.05). The activities of LV myocardial MMP-2 and -9 gelatinolytic were increased significantly in ADR rats (both P<0.01) and attenuated by valsartan treatment (both P<0.01). CONCLUSION: Pretreatment with AT1 receptor blocker valsartan attenuates left ventricular remodeling and failure in a rat model of adriamycin-induced dilated cardiomyopathy.