Intermittent hypoxia has been shown to provide myocardial protection against ishemia/reperfusion-induced injury.Cardiac myocyte loss through apoptosis has been reported in ischemia/reperfusion injury. Our aim was to i...Intermittent hypoxia has been shown to provide myocardial protection against ishemia/reperfusion-induced injury.Cardiac myocyte loss through apoptosis has been reported in ischemia/reperfusion injury. Our aim was to investigate whether intermittent hypoxia could attenuate ischemia/reperfusion-induced apoptosis in cardiac myocytes and its potential mechanisms. Adult male Sprague-Dawley rats were exposed to hypoxia simulated 5000 m in a hypobaric chamber for 6 h/day, lasting 42 days. Normoxia group rats were kept under normoxic conditions. Isolated perfused hearts from both groups were subjected to 30 min of global ischemia followed by 60 min reperfusion.Incidence of apoptosis in cardiac myocytes was determined by terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) and DNA agarose gel electrophoresis. Expressions of apoptosis related proteins,Bax and Bcl-2, in cytosolic and membrane fraction were detected by Western Blotting. After ischemia/reperfusion,enhanced recovery of cardiac function was observed in intermittent hypoxia hearts compared with normoxia group.Ischemia/reperfusion-induced apoptosis, as evidenced by TUNEL-positive nuclei and DNA fragmentation, was significantly reduced in intermittent hypoxia group compared with normoxia group. After ischemia/reperfusion,expression of Bax in both cytosolic and membrane fractions was decreased in intermittent hypoxia hearts compared with normoxia group. Although ischemia/reperfusion did not induce changes in the level of Bcl-2 expression in cytosolic fraction between intermittent hypoxia and normoxia groups, the expression of Bcl-2 in membrane fraction was upregulated in intermittent hypoxia group compared with normoxia group. These results indicated that the cardioprotection of intermittent hypoxia against ischemia/reperfusion injury appears to be in part due to reduce myocardial apoptosis. Intermittent hypoxia attenuated ischemia/reperfusion-induced apoptosis via increasing the ratio of Bcl-2/Bax, especially in membrane fraction.展开更多
The hyperpolarization-activated current (If) plays an important role in determining the spontaneous rate of cardiac pacemaker cells. The automatic rhythmicity also exists in working cells of embryonic heart, therefore...The hyperpolarization-activated current (If) plays an important role in determining the spontaneous rate of cardiac pacemaker cells. The automatic rhythmicity also exists in working cells of embryonic heart, therefore we studied developmental changes in functional expression and β-adrenergic regulation of Iy in embryonic mouse heart. The expression of If is high in early developmental stage (EDS) (10.5 d after coitus) ventricular myocytes, low in intermediate developmental stage (IDS) (13.5 d) atrial or ventricular myocytes and even lower in late developmental stage (LDS) (16.5 d) atrial or ventricular myocytes, indicating that these cells of the EDS embryonic heart have some properties of pacemaker cells.β-adrenergic agonist isoproterenol (ISO) stimulates If in LDS but not in EDS cardiomyocytes, indicating that the β-adrenergic regulation of If is not mature in EDS embryonic heart. But forskolin (a direct activator of adenylate cyclase) and 8-Br-cAMP (a membrane-permeable analogue of cAMP) increase the amplitude of If in EDS cells, indicating that adenylate cyclase and cAMP function fairly well at early stage of development. Furthermore, the results demonstrate that If is modulated by phosphorylation via cAMP dependent PKA both in EDS and LDS cells.展开更多
Mesenchymal stem cell differentiation towards osteogenic, chondrogenic and adipogenic lineages have been extensively described and reproduced in the literature. In contrast, cardiomyogenic differentiation still remain...Mesenchymal stem cell differentiation towards osteogenic, chondrogenic and adipogenic lineages have been extensively described and reproduced in the literature. In contrast, cardiomyogenic differentiation still remains largely controversial. In this study the authors aim to shed new light into this unclear phenomenon and test whether BMMSC （bone marrow mesenchymal stem cells） and ATMSC （adipose tissue derived mesenchymal stem cells） are able to differentiate into functional cardiomyocytes, investigating two differentiation protocols. AT and BMMSC behaved differently when cultured in differentiation media and presented lower levels of proliferation and alkaline phosphatase production, expression of cardiomyocyte-specific transcription factors such as GATA-4, Nkx2-5 and proteins such as ct and 13 Myosin Heavy Chains. Furthermore, MSC started to express higher levels of Connexin-43 and c~ sarcomeric actinin protein. Unfortunately, though, MSC did not present cardiomyocyte-like electrophysiological properties. In order to analyze a possible explanation for such limited plasticity, the authors decided to address the issue using a quantitative approach. Gene expression was quantified by Real time PCR, and, for the first time, the authors show that a possible explanation for limited plasticity of MSC is that even though differentiated cells presented differential gene expression, the levels of key cardiomyogenic genes did not reach expression levels presented by adult cardiomyocytes, nor were maintained along differentiation, reaching peaks at 4 days of stimulation, and decaying thereafter.展开更多
Objective： To investigate whether remifentanil induced cardioprotecting effect is associated with expression of toll-like receptor 4 （TLR4）, nuclear factor rB （NF-r.B） and serum interleukin -6 （IL-6）. Methods：...Objective： To investigate whether remifentanil induced cardioprotecting effect is associated with expression of toll-like receptor 4 （TLR4）, nuclear factor rB （NF-r.B） and serum interleukin -6 （IL-6）. Methods： Fifty rabbits were randomly divided into 5 groups （n=10） according to the treatment： sham operation group （group A）, ischemla-reperfusion group （group B）, low-dose remifentanil group （group C）, mediate-dose remifentanil group （group D）, and high-dose remlfentanil group （group E） Myocardial TLR4 mRNA levels, NF-r.B protein expression and serum levels of IL-6 were observed in 120 min after reperfusion. Results： The myocardial expressions of TLR4 mRNA, NF-rd3 protein and IL-6 level in sera of groups B, C, D and E were elevated compared with group A. However, remifentanil significantly reduced the levels of TLR4 mRNA, NF- r.B protein expression and serum IL-6 in groups C, D and E compared with group B. There were remarkable differences between the groups （P〈O.O1）. Conclusion： Intravenous remifentanil has protective effect against rabbit myocardial ischemia/reperfusion injury. This effect may be associated with TLR4, NF-r.B expressions on myocytes and serum level of IL-6 in a dose-dependent manner展开更多
Objective To investigate the effect of peroxisome proliferator-activated receptor-α(PPARα) and PPARγactivators on tumor necrosis factor-α(TNFα) expression in neonatal rat cardiac myocytes. Methods Primary culture...Objective To investigate the effect of peroxisome proliferator-activated receptor-α(PPARα) and PPARγactivators on tumor necrosis factor-α(TNFα) expression in neonatal rat cardiac myocytes. Methods Primary cultures of cardiac myocytes from 1- to 3-day-old Wistar rats were prepared, and myocytes were ex-posed to lipopolysaccharide (LPS) and varying concentrations of PPARαor PPARγactivator (fenofibrate or pioglitazone).RT-PCR and ELISA were used to measure TNFα, PPARα, and PPARγexpression in cultured cardiac myocytes. Transient tr-ansfection of TNFαpromoter with or without nuclear factor-kappaB (NF-κB) binding site to cardiac myocytes was performed. Results Pretreatment of cardiac myocytes with fenofibrate or pioglitazone inhibited LPS-induced TNFαmRNA and protein expression in a dose-dependent manner. However, no significant changes were observed on PPARαor PPARγmRNA expression when cardiac myocytes were pretreated with fenofibrate or pioglitazone. Proportional suppression of TNFαpromoter activity was observed when myocytes was transiently transfected with whole length of TNFαpromoter (-721/+17) after being stimulated with LPS and fenofibrate or pioglitazone, whereas no change of promoter activity was observed with transfection of TNFαreporter construct in deletion of NF-κB binding site (-182/+17). Conclusions PPARαand PPARγactivators may inhibit cardiac TNFαexpression but not accompanied by change of PPARαor PPARγmRNA expression. Therefore PPARαand PPARγactivators appear to play a role in anti-inflammation. The mechanism may partly be involved in suppression of the NF-κB pathway.展开更多
Purpose. To clarify the role of perforin-and Fas ligand (L)-mediated cytotoxicity pathogenesis of viral myocarditis. Materials and methods. Forty balb/c mice were randomly divided into experimental group (n = 20) and ...Purpose. To clarify the role of perforin-and Fas ligand (L)-mediated cytotoxicity pathogenesis of viral myocarditis. Materials and methods. Forty balb/c mice were randomly divided into experimental group (n = 20) and control group (n = 20), and inoculated intraperitoneally with coxsackievirus B3(CVB3) and Eagle’s solu- tion without CVB3, respectively. The mice were sacrificed and their hearts were removed at day 7 post-in- oculation. Expression of perform and FasL were detected with immunohistochemistry, reverse transcription-polymerase chain reaction (RT-PCR) and in situ hybridization. Results. (1)Perform-and FasL-positiye cells were demonstrated in experimental murine hearts by im- munohistochemistry, however, no cells were discovered in control murine hearts; (2) The examination of RT-PCR showed the positive ratios of perform and FasL mRNA in myocardium were significantly higher in experimental group (100% and 100 % ) than that in control group (20% and 30 %, P<0.05); (3)Positive signals of perform and FasL mRNA were found in myocardium of all the experimental mice by in situ hybridization, but nothing was detected in control group. Conclusion. Perform and FasL can be expressed in infiltrating cells in murine myocardium with acute myocarditis caused by CVB3, suggesting perform and FasL might play an important role in pathogenesis of viral myocarditis.展开更多
OBJECTIVE:To investigate the effects of electronic stimulation at acupoints Neiguan(PC 6) and Lieque(LU 7) on the gene expression of the adenosine triphosphate(ATP)-Sensitive potassium channel(KATP:Kir6.1,Kir6.2,SUR2 ...OBJECTIVE:To investigate the effects of electronic stimulation at acupoints Neiguan(PC 6) and Lieque(LU 7) on the gene expression of the adenosine triphosphate(ATP)-Sensitive potassium channel(KATP:Kir6.1,Kir6.2,SUR2 A,and SUR2B) and protein kinases(PKA,PKG,and PKCβ2) in myocardial cells of rats with myocardial ischemia(Ml) induced by isoproterenol(ISO).METHODS:Rats were randomly divided into a control,model,Neiguan(PC 6),Lieque(LU 7),and non-acupoint groups.The Ml model was established by injecting rats with ISO.Electro-acupuncture treatment was given to the acupuncture groups,once a day for 7 days.Gene expression was analyzed with real-time PCR.RESULTS:The gene expression of KATP and protein kinases in the model group was higher than those in the control group(P < 0.05).After acupuncture treatment,the KATP and protein kinase expression levels were significantly lower in the Neiguan(PC 6)and Lieque(LU 7) groups compared with the model group[P < 0.05).The Neiguan(PC 6) group lowered these levels significantly more than that of the Lieque(LU 7) group(P < 0.05).No significant differences were observed between the model and non-acupoint groups(P > 0.05).CONCLUSION:Our findings suggest that electronic needling of Neiguan(PC 6) can both reduce the gene expression of KATP and protein kinases in rats with ISO-induced Ml.展开更多
基金The study was supported by grants from National Natural Science Foundation of Chinathe Science and Technology committee of Shanghai Municipality(02JC14038).
文摘Intermittent hypoxia has been shown to provide myocardial protection against ishemia/reperfusion-induced injury.Cardiac myocyte loss through apoptosis has been reported in ischemia/reperfusion injury. Our aim was to investigate whether intermittent hypoxia could attenuate ischemia/reperfusion-induced apoptosis in cardiac myocytes and its potential mechanisms. Adult male Sprague-Dawley rats were exposed to hypoxia simulated 5000 m in a hypobaric chamber for 6 h/day, lasting 42 days. Normoxia group rats were kept under normoxic conditions. Isolated perfused hearts from both groups were subjected to 30 min of global ischemia followed by 60 min reperfusion.Incidence of apoptosis in cardiac myocytes was determined by terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) and DNA agarose gel electrophoresis. Expressions of apoptosis related proteins,Bax and Bcl-2, in cytosolic and membrane fraction were detected by Western Blotting. After ischemia/reperfusion,enhanced recovery of cardiac function was observed in intermittent hypoxia hearts compared with normoxia group.Ischemia/reperfusion-induced apoptosis, as evidenced by TUNEL-positive nuclei and DNA fragmentation, was significantly reduced in intermittent hypoxia group compared with normoxia group. After ischemia/reperfusion,expression of Bax in both cytosolic and membrane fractions was decreased in intermittent hypoxia hearts compared with normoxia group. Although ischemia/reperfusion did not induce changes in the level of Bcl-2 expression in cytosolic fraction between intermittent hypoxia and normoxia groups, the expression of Bcl-2 in membrane fraction was upregulated in intermittent hypoxia group compared with normoxia group. These results indicated that the cardioprotection of intermittent hypoxia against ischemia/reperfusion injury appears to be in part due to reduce myocardial apoptosis. Intermittent hypoxia attenuated ischemia/reperfusion-induced apoptosis via increasing the ratio of Bcl-2/Bax, especially in membrane fraction.
基金supported by the National Natural Science Foundation of China,No.30070279
文摘The hyperpolarization-activated current (If) plays an important role in determining the spontaneous rate of cardiac pacemaker cells. The automatic rhythmicity also exists in working cells of embryonic heart, therefore we studied developmental changes in functional expression and β-adrenergic regulation of Iy in embryonic mouse heart. The expression of If is high in early developmental stage (EDS) (10.5 d after coitus) ventricular myocytes, low in intermediate developmental stage (IDS) (13.5 d) atrial or ventricular myocytes and even lower in late developmental stage (LDS) (16.5 d) atrial or ventricular myocytes, indicating that these cells of the EDS embryonic heart have some properties of pacemaker cells.β-adrenergic agonist isoproterenol (ISO) stimulates If in LDS but not in EDS cardiomyocytes, indicating that the β-adrenergic regulation of If is not mature in EDS embryonic heart. But forskolin (a direct activator of adenylate cyclase) and 8-Br-cAMP (a membrane-permeable analogue of cAMP) increase the amplitude of If in EDS cells, indicating that adenylate cyclase and cAMP function fairly well at early stage of development. Furthermore, the results demonstrate that If is modulated by phosphorylation via cAMP dependent PKA both in EDS and LDS cells.
文摘Mesenchymal stem cell differentiation towards osteogenic, chondrogenic and adipogenic lineages have been extensively described and reproduced in the literature. In contrast, cardiomyogenic differentiation still remains largely controversial. In this study the authors aim to shed new light into this unclear phenomenon and test whether BMMSC （bone marrow mesenchymal stem cells） and ATMSC （adipose tissue derived mesenchymal stem cells） are able to differentiate into functional cardiomyocytes, investigating two differentiation protocols. AT and BMMSC behaved differently when cultured in differentiation media and presented lower levels of proliferation and alkaline phosphatase production, expression of cardiomyocyte-specific transcription factors such as GATA-4, Nkx2-5 and proteins such as ct and 13 Myosin Heavy Chains. Furthermore, MSC started to express higher levels of Connexin-43 and c~ sarcomeric actinin protein. Unfortunately, though, MSC did not present cardiomyocyte-like electrophysiological properties. In order to analyze a possible explanation for such limited plasticity, the authors decided to address the issue using a quantitative approach. Gene expression was quantified by Real time PCR, and, for the first time, the authors show that a possible explanation for limited plasticity of MSC is that even though differentiated cells presented differential gene expression, the levels of key cardiomyogenic genes did not reach expression levels presented by adult cardiomyocytes, nor were maintained along differentiation, reaching peaks at 4 days of stimulation, and decaying thereafter.
基金Supported by Shaanxi Provincial Scientific and Technological Research Projects (2008K13-02)
文摘Objective： To investigate whether remifentanil induced cardioprotecting effect is associated with expression of toll-like receptor 4 （TLR4）, nuclear factor rB （NF-r.B） and serum interleukin -6 （IL-6）. Methods： Fifty rabbits were randomly divided into 5 groups （n=10） according to the treatment： sham operation group （group A）, ischemla-reperfusion group （group B）, low-dose remifentanil group （group C）, mediate-dose remifentanil group （group D）, and high-dose remlfentanil group （group E） Myocardial TLR4 mRNA levels, NF-r.B protein expression and serum levels of IL-6 were observed in 120 min after reperfusion. Results： The myocardial expressions of TLR4 mRNA, NF-rd3 protein and IL-6 level in sera of groups B, C, D and E were elevated compared with group A. However, remifentanil significantly reduced the levels of TLR4 mRNA, NF- r.B protein expression and serum IL-6 in groups C, D and E compared with group B. There were remarkable differences between the groups （P〈O.O1）. Conclusion： Intravenous remifentanil has protective effect against rabbit myocardial ischemia/reperfusion injury. This effect may be associated with TLR4, NF-r.B expressions on myocytes and serum level of IL-6 in a dose-dependent manner
基金Supported by the National Nature Science Foundation of China (30270551) and Military "10.5"Foundation (02M012).
文摘Objective To investigate the effect of peroxisome proliferator-activated receptor-α(PPARα) and PPARγactivators on tumor necrosis factor-α(TNFα) expression in neonatal rat cardiac myocytes. Methods Primary cultures of cardiac myocytes from 1- to 3-day-old Wistar rats were prepared, and myocytes were ex-posed to lipopolysaccharide (LPS) and varying concentrations of PPARαor PPARγactivator (fenofibrate or pioglitazone).RT-PCR and ELISA were used to measure TNFα, PPARα, and PPARγexpression in cultured cardiac myocytes. Transient tr-ansfection of TNFαpromoter with or without nuclear factor-kappaB (NF-κB) binding site to cardiac myocytes was performed. Results Pretreatment of cardiac myocytes with fenofibrate or pioglitazone inhibited LPS-induced TNFαmRNA and protein expression in a dose-dependent manner. However, no significant changes were observed on PPARαor PPARγmRNA expression when cardiac myocytes were pretreated with fenofibrate or pioglitazone. Proportional suppression of TNFαpromoter activity was observed when myocytes was transiently transfected with whole length of TNFαpromoter (-721/+17) after being stimulated with LPS and fenofibrate or pioglitazone, whereas no change of promoter activity was observed with transfection of TNFαreporter construct in deletion of NF-κB binding site (-182/+17). Conclusions PPARαand PPARγactivators may inhibit cardiac TNFαexpression but not accompanied by change of PPARαor PPARγmRNA expression. Therefore PPARαand PPARγactivators appear to play a role in anti-inflammation. The mechanism may partly be involved in suppression of the NF-κB pathway.
文摘Purpose. To clarify the role of perforin-and Fas ligand (L)-mediated cytotoxicity pathogenesis of viral myocarditis. Materials and methods. Forty balb/c mice were randomly divided into experimental group (n = 20) and control group (n = 20), and inoculated intraperitoneally with coxsackievirus B3(CVB3) and Eagle’s solu- tion without CVB3, respectively. The mice were sacrificed and their hearts were removed at day 7 post-in- oculation. Expression of perform and FasL were detected with immunohistochemistry, reverse transcription-polymerase chain reaction (RT-PCR) and in situ hybridization. Results. (1)Perform-and FasL-positiye cells were demonstrated in experimental murine hearts by im- munohistochemistry, however, no cells were discovered in control murine hearts; (2) The examination of RT-PCR showed the positive ratios of perform and FasL mRNA in myocardium were significantly higher in experimental group (100% and 100 % ) than that in control group (20% and 30 %, P<0.05); (3)Positive signals of perform and FasL mRNA were found in myocardium of all the experimental mice by in situ hybridization, but nothing was detected in control group. Conclusion. Perform and FasL can be expressed in infiltrating cells in murine myocardium with acute myocarditis caused by CVB3, suggesting perform and FasL might play an important role in pathogenesis of viral myocarditis.
基金Supported by National Basic Research Program of China(973 Program)Study on Biological Foundation of Response in Target Organ to Meridian Specificity of Acupoint Effect(No.2012CB518503)
文摘OBJECTIVE:To investigate the effects of electronic stimulation at acupoints Neiguan(PC 6) and Lieque(LU 7) on the gene expression of the adenosine triphosphate(ATP)-Sensitive potassium channel(KATP:Kir6.1,Kir6.2,SUR2 A,and SUR2B) and protein kinases(PKA,PKG,and PKCβ2) in myocardial cells of rats with myocardial ischemia(Ml) induced by isoproterenol(ISO).METHODS:Rats were randomly divided into a control,model,Neiguan(PC 6),Lieque(LU 7),and non-acupoint groups.The Ml model was established by injecting rats with ISO.Electro-acupuncture treatment was given to the acupuncture groups,once a day for 7 days.Gene expression was analyzed with real-time PCR.RESULTS:The gene expression of KATP and protein kinases in the model group was higher than those in the control group(P < 0.05).After acupuncture treatment,the KATP and protein kinase expression levels were significantly lower in the Neiguan(PC 6)and Lieque(LU 7) groups compared with the model group[P < 0.05).The Neiguan(PC 6) group lowered these levels significantly more than that of the Lieque(LU 7) group(P < 0.05).No significant differences were observed between the model and non-acupoint groups(P > 0.05).CONCLUSION:Our findings suggest that electronic needling of Neiguan(PC 6) can both reduce the gene expression of KATP and protein kinases in rats with ISO-induced Ml.
