THE DISCONTINUOUS NATURE OF PROPAGATION IN NORMAL CANINE CARDIAC-MUSCLE - EVIDENCE FOR RECURRENT DISCONTINUITIES OF INTRACELLULAR RESISTANCE THAT AFFECT THE MEMBRANE CURRENTS
THE DISCONTINUOUS NATURE OF PROPAGATION IN NORMAL CANINE CARDIAC-MUSCLE - EVIDENCE FOR RECURRENT DISCONTINUITIES OF INTRACELLULAR RESISTANCE THAT AFFECT THE MEMBRANE CURRENTS
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DOI：
10.1161/01.res.48.1.39
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发表时间：
1981-01-01
影响因子：
20.1
通讯作者：
JOHNSON, EA
中科院分区：
文献类型：
--
作者：
SPACH, MS;MILLER, WT;JOHNSON, EA
当通过改变细胞的内阻来改变动作电位的传播速度时，电缆理论预测动作电位上行的形状不应该改变;与上行变化相关的速度变化通常归因于膜特性的变化。在正常的心肌中，上行程随速度的变化发生在膜特性不可能改变的条件下。研究了心房和心室肌中的传播，其中传播速度在相对于细胞取向的不同角度处是不同的。快速上升与低传播速度（在横向的长细胞轴的方向）和较慢的上升与高传播速度（在长细胞轴的方向）。这种去极化形状的变化可以由心肌的离散细胞性质来解释。细胞内电阻的周期性不连续性导致传播在微观尺度上是不连续的。细胞内电阻的不连续性的存在逆转了通常的高速度和高安全系数的传播的关联：在低速度下的传播比在较高速度下的传播更能抵抗膜特性的干扰。这种倒置的关系表明，传播可以继续在一个方向上横向的细胞的长轴时，块发生在纵向方向，与所得的折返传播。这种预测在心房肌中的过早动作电位的传播的研究中得到证实。
When the propagation velocity of action potentials is modified by changing the internal resistance of a cell, cable theory predicts that the shape of the action potential upstroke should not change; changes in velocity associated with changes in the upstroke usually are attributed to changes in membrane properties. In normal cardiac muscle changes in the upstroke with velocity occur under conditions in which the membrane properties could not have changed. Propagation in atrial and ventricular muscle was studied in which the velocity of propagation was different at different angles with respect to the cell orientation. Fast upstrokes were associated with low propagation velocities (in a direction transverse to the long cell axis) and slower upstrokes were associated with high propagation velocities (in the direction of the long cell axis). Such changes in the shape of depolarization can be accounted for by the discrete cellular nature of cardiac muscle. The recurrent discontinuities in intracellular resistance cause propagation to be discontinuous on a microscopic scale. The presence of discontinuities in intracellular resistance reverses the usual association of high velocity and high safety factor for propagation: propagation at a low velocity is more resistant to disturbances in membrane properties than is propagation at a higher velocity. This inverted relationship suggested that propagation could continue in a direction transverse to the long axis of the cells when block occurs in the longitudinal direction, with resultant reentrant propagation. Such prediction was confirmed in the study of the propagation of premature action potentials in atrial muscle.