Characteristics of pacemaker current in aged rat atrial myocytes |
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Authors: | LIN Kun LAN Yun-feng FANG Zhou GAO Jin-liao WANG Hong-juan LI Yang |
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Institution: | 1. Department of Cardiology, Chinese PLA General Hospital, Beijing 100853, China;
2. Institute of Geriatric Cardiology, Chinese PLA General Hospital, Beijing 100853, China |
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Abstract: | AIM: To investigate the characteristics of pacemker current (If) of atrium myocytes in aged rats. METHODS: Aged SD rats (22-24 months) were used in the study. The single atrium myocytes were isolated. If current was recorded by the technique of whole-cell patch clamp. RESULTS: The densities of If increased markedly in aged rat atrium myocytes compared with that in the cells of young rats. At the test potential of-150 mV, the average amplitude of If was (382±23)pA and the current density was (3.2±0.4)pA/pF, while the average amplitude of If in control group was (86.9±8.4)pA and the current density was (0.9±0.1)pA/pF,P<0.01. If current was augmented at negative hyperpolarzing test potential. Time constants of activation in aged and control cells were (230.2±14.4)ms and (670.5±23.6)ms, respectively. Furthermore, steady state curves in the elder cells was shifted to positive potentials and the voltages for half maximal activation were (-87.2±2.3)mV (aged cells) and (-104.4±6.3)mV (control cells). In contrast, the slope of activation curves and reversed potential of If were slightly different between aged cells and control cells. CONCLUSION: The amplitude and densities of If in atrium cells of aged rats were larger than that of control rats. |
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Keywords: | Aged rats Atrium myocytes Pacemaker current |
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