目的研究缺氧复氧(HR)后,抑制自噬对H9c2心肌细胞损伤的影响,同时观察线粒体Cx43含量及磷酸化水平的变化,探讨抑制自噬对HR心肌损伤的影响及可能机制。方法通过缺氧12h、复氧12h建立H9c2心肌细胞HR模型。随机将H9c2心肌细胞分为5组:对...目的研究缺氧复氧(HR)后,抑制自噬对H9c2心肌细胞损伤的影响,同时观察线粒体Cx43含量及磷酸化水平的变化,探讨抑制自噬对HR心肌损伤的影响及可能机制。方法通过缺氧12h、复氧12h建立H9c2心肌细胞HR模型。随机将H9c2心肌细胞分为5组:对照组、HR组、格尔德霉素(GA)组、3甲基腺嘌呤(3-MA)组、GA+3-MA组。分别测定各组细胞活力、线粒体膜电位以及人卷曲螺旋-肌球蛋白样BCL2结合蛋白(Beclin-1)、微管相关蛋白轻链3B(LC3B)、线粒体Cx43、线粒体磷酸化Cx43蛋白水平和自噬体含量。结果与对照组比较,HR组漂浮的死亡细胞增多、存活心肌细胞密度减少,细胞存活率和活力、线粒体膜电位下降,乳酸脱氢酶水平升高(P<0.05)。与HR组比较,GA组、3-MA组和GA+3-MA组线粒体膜电位、细胞活力均下降(P<0.05);GA+3-MA组线粒体膜电位、细胞活力均分别低于GA组和3-MA组(P<0.05)。与对照组相比,HR组自噬体增多、自噬相关蛋白Beclin-1水平和LC3BⅡ/LC3BⅠ均升高(P<0.05);与HR组比较,GA组、3-MA组和GA+3-MA组自噬体减少、Beclin-1水平GA、LC3BⅡ/LC3BⅠ均下降(P<0.05);GA+3-MA组Beclin-1水平、LC3BⅡ/LC3BⅠ均分别低于GA组和3-MA组(P<0.05)。与对照组比较,HR组线粒体Cx43及磷酸化Cx43蛋白均下降(P<0.05);GA组和GA+3-MA组线粒体Cx43蛋白低于HR组(P<0.05);GA组、3-MA组和GA+3-MA组线粒体磷酸化Cx43蛋白低于HR组(P<0.05);GA+3-MA组线粒体磷酸化Cx43蛋白分别低于GA组和3-MA组(0.18±0.04 vs 0.27±0.06,0.33±0.05,P<0.05)。结论 HR导致线粒体Cx43含量及磷酸化水平下降,心肌细胞出现缺血再灌注损伤,同时自噬激活。而抑制自噬,使HR后线粒体Cx43脱磷酸化加剧,进一步加重HR心肌细胞损伤。展开更多
T-wave alternans, a specific form of cardiac alternans, has been associated with the increased suscep- tibility to cardiac arrhythmias and sudden cardiac death （SCD）. Plenty of evidence has related cardiac alternans...T-wave alternans, a specific form of cardiac alternans, has been associated with the increased suscep- tibility to cardiac arrhythmias and sudden cardiac death （SCD）. Plenty of evidence has related cardiac alternans at the tissue level to the instability of voltage kinetics or Ca^2＋ handling dynamics at the cellular level. However, to date, none of the existing experiments could identify the exact cellular mechanism of cardiac alternans due to the bi-directional coupling between voltage kinetics and Ca^2＋ handling dynamics. Either of these systems could be the origin of alternans and the other follows as a secondary change, therefore making the cellular mechanism of alternans a difficult chicken or egg problem. In this context, theoretical analysis combined with experimental techniques provides a possibility to explore this problem. In this review, we will summarize the experimental and theoretical advances in understanding the cellular mechanism of alternans. We focus on the roles of action potential duration （APD） restitution and Ca^2＋ handling dynamics in the genesis of alternans and show how the theoretical analysis combined with experimental techniques has provided us a new insight into the cellular mechanism of alternans. We also discuss the possible reasons of increased propensity for alternans in heart failure （HF） and the new possible therapeutic targets. Finally, according to the level of electrophysiological recording techniques and theoretical strategies, we list some critical experimental or theoretical challenges which may help to determine the origin of alternans and to find more effective therapeutic tar- gets in the future.展开更多
The effect of Ce3+ on cardiac muscle of rat and guinea pig was studied. In vitro, 0.05 mmol·L-1 solution of Ce3+ inhibited the contraction of guinea pig atria. The change of action potential duration(APD) of gui...The effect of Ce3+ on cardiac muscle of rat and guinea pig was studied. In vitro, 0.05 mmol·L-1 solution of Ce3+ inhibited the contraction of guinea pig atria. The change of action potential duration(APD) of guinea pig papillary muscle exposed to 0.4 mmol·L-1 Ce3+ was significant, and those exposed to 0.1 and 0. 2 mmol·L-1 Ce3+ were not significant. In vivo, compared with the control group, the APD for rat cardiac muscle after long-term feed on Ce3+ was significantly delayed in high dose, and that was not significantly delayed in low dose. The results suggest that Ce3+ with long-term high dose intake might affect the influx of Ca2+, Na+ and outflow of K+ for rat cardiac muscle.展开更多
Objective To investigate the alterations of cardiac electrophysiological properties and substantial mechanism and find the stable arrhythmia mouse model in Kunming （KM） and C57BL6/J （C57） mice. Methods Electrocar...Objective To investigate the alterations of cardiac electrophysiological properties and substantial mechanism and find the stable arrhythmia mouse model in Kunming （KM） and C57BL6/J （C57） mice. Methods Electrocardiogram recordings were used to analyze the QT interval in vivo, and mono- phasic action potential of right and left ventricular epicardium was recorded to elicit changes of action potential duration （APD） in conventional and programmed electrical stimulation （PES）. Transient outward potassium current （Its,） was recorded via whole-cell patch-clamp technique in single right and left epicardial myocytes. Results QT interval was prolonged in KM mice relative to C57 mice （62.51±4.47 ms vs. 52.59±4.85 ms, P〈0.05）. The APD at 50% repolarization of the left ventricular epicardium （18.60±0.91 ms vs. 12.90±0.35 ms）, and APDs at 50% （17.31±6.05 ms vs. 12.00±3.24 ms） and 70% repolarization （36.13±5.32 ms vs. 2 1.95±8.06 ms） of the right ventricular epicardium in KM mice were significantly pro- longed compared with C57 mice, respectively （all P〈0.05）. KM mice were more sensitive to PES-induced ventricular tachycardia （25%, 3 of 12 hearts）, and especially to Burst-induced ventricular tachycardia （50%, 6 of 12 hearts） compared with C57 mice, which were 20% （2 of 10 hearts） and 30% （3 of 10 hearts） respec- tively. It,, densities both in the left and right ventricular epicardial myocytes from KM mice were significantly decreased compared with C57 mice, respectively （all P〈0.01）. Conclusion Our data showed that KM mice with tile prolonged QT interval and APD are ruiner- abilities to ventricular arrhythmia, which are attributed to lower Ito densities in ventricular myocytes ob- tained from KM mice than that from C57 mice.展开更多
文摘目的研究缺氧复氧(HR)后,抑制自噬对H9c2心肌细胞损伤的影响,同时观察线粒体Cx43含量及磷酸化水平的变化,探讨抑制自噬对HR心肌损伤的影响及可能机制。方法通过缺氧12h、复氧12h建立H9c2心肌细胞HR模型。随机将H9c2心肌细胞分为5组:对照组、HR组、格尔德霉素(GA)组、3甲基腺嘌呤(3-MA)组、GA+3-MA组。分别测定各组细胞活力、线粒体膜电位以及人卷曲螺旋-肌球蛋白样BCL2结合蛋白(Beclin-1)、微管相关蛋白轻链3B(LC3B)、线粒体Cx43、线粒体磷酸化Cx43蛋白水平和自噬体含量。结果与对照组比较,HR组漂浮的死亡细胞增多、存活心肌细胞密度减少,细胞存活率和活力、线粒体膜电位下降,乳酸脱氢酶水平升高(P<0.05)。与HR组比较,GA组、3-MA组和GA+3-MA组线粒体膜电位、细胞活力均下降(P<0.05);GA+3-MA组线粒体膜电位、细胞活力均分别低于GA组和3-MA组(P<0.05)。与对照组相比,HR组自噬体增多、自噬相关蛋白Beclin-1水平和LC3BⅡ/LC3BⅠ均升高(P<0.05);与HR组比较,GA组、3-MA组和GA+3-MA组自噬体减少、Beclin-1水平GA、LC3BⅡ/LC3BⅠ均下降(P<0.05);GA+3-MA组Beclin-1水平、LC3BⅡ/LC3BⅠ均分别低于GA组和3-MA组(P<0.05)。与对照组比较,HR组线粒体Cx43及磷酸化Cx43蛋白均下降(P<0.05);GA组和GA+3-MA组线粒体Cx43蛋白低于HR组(P<0.05);GA组、3-MA组和GA+3-MA组线粒体磷酸化Cx43蛋白低于HR组(P<0.05);GA+3-MA组线粒体磷酸化Cx43蛋白分别低于GA组和3-MA组(0.18±0.04 vs 0.27±0.06,0.33±0.05,P<0.05)。结论 HR导致线粒体Cx43含量及磷酸化水平下降,心肌细胞出现缺血再灌注损伤,同时自噬激活。而抑制自噬,使HR后线粒体Cx43脱磷酸化加剧,进一步加重HR心肌细胞损伤。
基金Project supported by the National Basic Research Program （973） of China （No. 2007CB512100） and the National Natural Science Foun- dation of China （Nos. 81171421 and 61101046）
文摘T-wave alternans, a specific form of cardiac alternans, has been associated with the increased suscep- tibility to cardiac arrhythmias and sudden cardiac death （SCD）. Plenty of evidence has related cardiac alternans at the tissue level to the instability of voltage kinetics or Ca^2＋ handling dynamics at the cellular level. However, to date, none of the existing experiments could identify the exact cellular mechanism of cardiac alternans due to the bi-directional coupling between voltage kinetics and Ca^2＋ handling dynamics. Either of these systems could be the origin of alternans and the other follows as a secondary change, therefore making the cellular mechanism of alternans a difficult chicken or egg problem. In this context, theoretical analysis combined with experimental techniques provides a possibility to explore this problem. In this review, we will summarize the experimental and theoretical advances in understanding the cellular mechanism of alternans. We focus on the roles of action potential duration （APD） restitution and Ca^2＋ handling dynamics in the genesis of alternans and show how the theoretical analysis combined with experimental techniques has provided us a new insight into the cellular mechanism of alternans. We also discuss the possible reasons of increased propensity for alternans in heart failure （HF） and the new possible therapeutic targets. Finally, according to the level of electrophysiological recording techniques and theoretical strategies, we list some critical experimental or theoretical challenges which may help to determine the origin of alternans and to find more effective therapeutic tar- gets in the future.
基金the National Natural Science Foundation of China!29671034
文摘The effect of Ce3+ on cardiac muscle of rat and guinea pig was studied. In vitro, 0.05 mmol·L-1 solution of Ce3+ inhibited the contraction of guinea pig atria. The change of action potential duration(APD) of guinea pig papillary muscle exposed to 0.4 mmol·L-1 Ce3+ was significant, and those exposed to 0.1 and 0. 2 mmol·L-1 Ce3+ were not significant. In vivo, compared with the control group, the APD for rat cardiac muscle after long-term feed on Ce3+ was significantly delayed in high dose, and that was not significantly delayed in low dose. The results suggest that Ce3+ with long-term high dose intake might affect the influx of Ca2+, Na+ and outflow of K+ for rat cardiac muscle.
基金Supported by the National Natural Science Foundation of China(81070142)Natural Science Foundation of Hubei Province (2011CDB504)
文摘Objective To investigate the alterations of cardiac electrophysiological properties and substantial mechanism and find the stable arrhythmia mouse model in Kunming （KM） and C57BL6/J （C57） mice. Methods Electrocardiogram recordings were used to analyze the QT interval in vivo, and mono- phasic action potential of right and left ventricular epicardium was recorded to elicit changes of action potential duration （APD） in conventional and programmed electrical stimulation （PES）. Transient outward potassium current （Its,） was recorded via whole-cell patch-clamp technique in single right and left epicardial myocytes. Results QT interval was prolonged in KM mice relative to C57 mice （62.51±4.47 ms vs. 52.59±4.85 ms, P〈0.05）. The APD at 50% repolarization of the left ventricular epicardium （18.60±0.91 ms vs. 12.90±0.35 ms）, and APDs at 50% （17.31±6.05 ms vs. 12.00±3.24 ms） and 70% repolarization （36.13±5.32 ms vs. 2 1.95±8.06 ms） of the right ventricular epicardium in KM mice were significantly pro- longed compared with C57 mice, respectively （all P〈0.05）. KM mice were more sensitive to PES-induced ventricular tachycardia （25%, 3 of 12 hearts）, and especially to Burst-induced ventricular tachycardia （50%, 6 of 12 hearts） compared with C57 mice, which were 20% （2 of 10 hearts） and 30% （3 of 10 hearts） respec- tively. It,, densities both in the left and right ventricular epicardial myocytes from KM mice were significantly decreased compared with C57 mice, respectively （all P〈0.01）. Conclusion Our data showed that KM mice with tile prolonged QT interval and APD are ruiner- abilities to ventricular arrhythmia, which are attributed to lower Ito densities in ventricular myocytes ob- tained from KM mice than that from C57 mice.
