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@#Objective To detect whether the cardiomyocyte-like cells differentiated from human marrow mesenchymal stem cells (hMSCs) could produce action potential (AP). Methods Isolated and cultured hMSCs were induced into cardiomyocyte-like cells with 5-Azacytine in vitro. They were measured for their AP by patch clamp technique, and compared with those of hMSCs of the same generation and beating cardiomyocytes (CMs) derived from 2 day-old SD rats. Results 6/30 cardiomyocyte-like cells produced AP. The CMs produced significant AP, hMSCs appeared no AP, and cardiomyocyte-like cells appeared weak AP. Conclusion The hMSCs manifested the potential to differentiate into CMs in the electrophysiology characteristics following 5-Azacytine induction.
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Aim To investigate the effects of PB-19 on action potential (AP) of ventricular cells in vitro and ischemia and reperfusion induced arrhythmias in vivo in rats. Methods ① We established the model of isolated rat right ventricular wall and perfused the models with normal Tyrode’s solution and PB-19.Microelectrode was inserted into the cells to record the AP. ② We ligated the left anterior descending coronary artery of rats to study the effects of PB-19 on ischemia and reperfusion induced arrhythmias. 50 rats were divided into 5 groups randomly and were given iv. injection with normal saline and PB-19 of different concentrations respectively. We recorded Ⅱ ECG of the rats. Results ①In vitro models, the APD_ 50、APD_ 90 of PB-19 group were significantly longer than that of control group respectively (P
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AIM To study the effects of matrine (Ma) on the action potential and contractile force in guinea pig papillary muscles. METHODS Conventional microelectrode technique was used to record the fast action potentials (FAP) and slow action potentials (SAP) induced by histamine and BaCl_2 of guinea pig papillary muscles. RESULTS Ma 10,25,50 ?mol?L -1 dose-dependently prolonged the action potential duration at 50%, 90% repolarization (APD_ 50 , APD_ 90 ) and effective refractory period (ERP) of FAP, and lengthened the APD_ 50 , APD_ 90 of SAP induced by histamine and BaCl_2 when perfused with KCl 25 mmol?L -1 Tyrode's solution. The maximal upstroke velocity (V_ max ) of FAP, SAP and contractile force (Fc) were not affected by matrine 10,25,50 ?mol?L -1 . CONCLUSION It was suggested that Matrine could block K + channels in the myocardium.-