Effects of mechanical stretch on electrophysiological characteristics of calcium preconditioning myocardium |
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Authors: | WANG Zhi-qiang CHENG Long-xian LIAO Yu-hua HU Heng-liang WANG Jia-ling SHENG Fu-qiang LI Xing-hai |
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Institution: | 1.Department of Cardiovascular Internal Medicine,4Department of Cardiovascular Surgery, The Affiliated Union Hospital, Tongji Medical College of Huazhong University of Science and Technology, Wuhan 430022, China;3.Department of Pharmacology, School of Basic Medical Sciences, Tongji Medical College of Huazhong University of Science and Technology, Wuhan 430030, China;2Medical School in Huanggang City, Hubei 438000, China |
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Abstract: | AIM: To investigate the effects of mechanical stretch under simulated anoxia and reoxygenation conditions on action potential (AP) and effective refractory period (ERP) of calcium preconditioning (CPC) in isolated papillary muscles of guinea pig hearts. METHODS: The intracellular standard glass microelectrode technique was used, and effects of stretch (intensity: 200 mg) on AP and ERP were recorded and observed in CPC papillary muscles. RESULTS: After stretching was implied during anoxia, the reductions of Vmax, RP, APA, APD50, ERP and APD90 in CPC group were less than those in anoxia-reoxygenation (AR) group, and the CT in CPC group was less elongated. Moreover, after the papillary muscles were stretched during reoxygenated reperfusion, the decreases in Vmax, RP, APA, APD50 and ERP in CPC group were less than those in AR group, and the CT and APD90 in CPC group were less extended. Streptomycin inhibited the effect of stretch on AP and ERP in CPC group. CONCLUSIONS: Under simulated anoxia and reoxygenation conditions, papillary muscles in CPC group may have better tolerance to the same stretch than those in the AR. Furthermore, streptomycin (a blockade of stretch-activated ionic channels) may inhibit the effect of mechanical stretch on action potential changes in CPC papillary muscles. |
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