Determinants of action potential initiation in isolated rabbit atrial and ventricular myocytes
Determinants of action potential initiation in isolated rabbit atrial and ventricular myocytes
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DOI：
10.1152/ajpheart.1998.274.6.h1902
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发表时间：
1998-06-01
影响因子：
4.8
通讯作者：
Joyner, RW
中科院分区：
文献类型：
--
作者：
Golod, DA;Kumar, R;Joyner, RW
通过心脏心房和心室的动作电位传导取决于心房和心室细胞的膜特性，特别是关于每种细胞类型中动作电位启动的决定因素。我们对分离的细胞使用电流钳和电压钳技术来检查两种细胞类型在生理温度下的生物物理特性。心房细胞测量的静息膜电位、动作电位幅度、电流阈值、电压阈值和最大上升速率（分别为-80 +/- 1 mV、109 +/- 3 mV、0.69 +/- 0.05 nA、-59 +/- 1 mV 和 206 +/- 17 V/s；平均值+/- SE）与心室细胞测量的值显着不同（P < 0.05） （分别为-82.7 +/- 0.4 mV、127 +/- 1 mV、2.45 +/- 0.13 nA、-46 +/- 2 mV 和 395 +/- 21 V/s）。心房（分别为 341 +/- 41 M Omega、70 +/- 4 pF、23.8 +/- 2.3 ms 和 19 +/- 1 mV）和心室（16.5 +/- 5.4 M Omega、99 +/- 4.3 pF、1.56 +/- 0.32 ms、和 36 +/- 1 mV）细胞。这些差异的主要机制是心室细胞中的内向整流钾电流的幅度比心房细胞中的要大得多，另外的差异是心房细胞中的内向钠电流的可用性明显较低。两种细胞类型的这些差异可能对于心房细胞被正常的自动性区域（例如窦房结）成功驱动很重要，而心室细胞会抑制自动性区域（例如异位焦点）的动作电位启动。
Action potential conduction through the atrium and the ventricle of the heart depends on the membrane properties of the atrial and ventricular cells, particularly with respect to the determinants of the initiation of action potentials in each cell type. We have utilized both current-and voltage-clamp techniques on isolated cells to examine biophysical properties of the two cell types at physiological temperature. The resting membrane potential, action potential amplitude, current threshold, voltage threshold, and maximum rate of rise measured from atrial cells (-80 +/- 1 mV, 109 +/- 3 mV, 0.69 +/- 0.05 nA, -59 +/- 1 mV, and 206 +/- 17 V/s, respectively; means +/- SE) differed significantly (P < 0.05) from those values measured from ventricular cells (-82.7 +/- 0.4 mV, 127 +/- 1 mV, 2.45 +/- 0.13 nA, -46 +/- 2 mV, and 395 +/- 21 V/s, respectively). Input impedance, capacitance, time constant, and critical depolarization for activation also were significantly different between atrial (341 +/- 41 M Omega, 70 +/- 4 pF, 23.8 +/- 2.3 ms, and 19 +/- 1 mV, respectively) and ventricular (16.5 +/- 5.4 M Omega, 99 +/- 4.3 pF, 1.56 +/- 0.32 ms, and 36 +/- 1 mV, respectively) cells. The major mechanism of these differences is the much greater magnitude of the inward rectifying potassium current in ventricular cells compared with that in atrial cells, with an additional difference of an apparently lower availability of inward Na current in atrial cells. These differences in the two cell types may be important in allowing the atrial cells to be driven successfully by normal regions of automaticity (e.g., the sinoatrial node), whereas ventricular cells would suppress action potential initiation from a region of automaticity (e.g., an ectopic focus).