Correlation between electrical activity and the size of rabbit sino-atrial node cells
Correlation between electrical activity and the size of rabbit sino-atrial node cells
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DOI：
10.1113/jphysiol.1996.sp021728
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发表时间：
1996-11-01
影响因子：
5.5
通讯作者：
Toyama, J
中科院分区：
文献类型：
--
作者：
Honjo, H;Boyett, MR;Toyama, J
1.通过酶解从兔窦房结(SA)中分离单细胞。采用全细胞膜片钳技术记录自发动作电位和膜电流，研究电活动与细胞大小的关系。 2． SA 节点细胞的大小通过测量细胞电容来估计。 SA 节点单元的单元电容范围为 21.8 至 61.5 pF，平均值为 +/- S.E.M。 38.2 +/- 1.3 pF (n = 61).3。较大的细胞的动作电位幅度、最大舒张电位、起跳电位和动作电位上冲速度较大。细胞越大，舒张期去极化速率越大，内在自发活动越快。4．细胞越大，超极化激活电流(i(f))密度越大，而L型钙电流密度与SE结细胞大小不相关。5．在电容小于25 pF的小细胞中不存在TTX敏感的钠电流(i(Na))，并且在较大的细胞中i(Na)的密度更大。6．较大细胞中较大的 i(Na) 密度可以解释大细胞中动作电位的较高上冲速度，而较大的 i(f) 和 i(Na) 密度可能是大细胞更快的内在自发活动的原因。这些结果表明 SA 节点由具有不同电膜特性的电生理异质起搏细胞组成。
1. Single cells were isolated from rabbit sino-atrial (SA) node by enzymatic dissociation. Spontaneous action potentials and membrane currents were recorded using the whole-cell patch clamp technique to study the relationship between electrical activity and the size of the cells.2. The size of SA node cells was estimated bs measuring the cell capacitance. The cell capacitance of SA node cells ranged from 21.8 to 61.5 pF with a mean +/- S.E.M. of 38.2 +/- 1.3 pF (n = 61).3. The action potential amplitude, maximum diastolic potential, take-off potential and action potential upstroke velocity were greater in larger cells. The rate of diastolic depolarization was greater and the intrinsic spontaneous activity was faster in larger cells.4. The density of hyperpolarization-activated current (i(f)) was greater in larger cells, whereas the density of L-type calcium current was not correlated with the size of SE node cells.5. TTX-sensitive sodium current (i(Na)) was absent in small cells with a capacitance of less than similar to 25 pF, and the density of i(Na) was greater in larger cells.6. The greater density of i(Na) in larger cells may explain the higher upstroke velocity of the action potential in large cells, and the greater density of i(f) and i(Na) could be responsible for the faster intrinsic spontaneous activity of large cells. These results suggest that the SA node consists of electrophysiologically heterogeneous pacemaker cells with different electrical membrane properties.