Mechanism of repolarization alternans has restitution of action potential duration dependent and independent components
Mechanism of repolarization alternans has restitution of action potential duration dependent and independent components
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DOI：
10.1111/j.1540-8167.2005.00319.x
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发表时间：
2006-01-01
影响因子：
2.7
通讯作者：
Patwardhan, A
中科院分区：
文献类型：
--
作者：
Wu, RZ;Patwardhan, A
APD 的舒张期间隔和交替。简介：对舒张期 (DI) 依赖性动作电位持续时间 (APD) 恢复与 APD 交替值之间关系的研究产生了相互矛盾的结果。我们使用一种新颖的起搏方案，通过最大限度地减少每次激活之前 DI 的变化来确定恢复在交替中的作用。方法：记录从五只狗分离的右心室心内膜组织的跨膜电位。我们使用了三种起搏序列：(i) 组织以恒定 DI 起搏 100 次。 (ii) DI 在两个恒定 DI 序列之间随机变化。 (iii)每次恒定 DI 试验之后进行恒定周期长度试验，其中起搏周期长度等于先前恒定 DI 试验期间的平均周期长度。结果：即使每次激活之前的 DI 不变，也会发生 APD 交替。持续 DI 起搏期间的恢复斜率既有负值也有正值，并且远大于统一斜率。恒定周期长度起搏期间的交替振幅大于恒定 DI 期间的交替振幅，分别为 32.2 +/- 12.3 与 7.5 +/- 2.8 毫秒，P < 0.01。 DI 的随机扰动使恒定 DI 起搏期间的交替振幅从 14.7 +/- 4.8 降低到 10.5 +/- 3.4 毫秒，P < 0.01。结论：我们的结果表明复极交替机制具有恢复依赖性和恢复独立性。然而，我们的结果也提供了直接证据，表明 DI 依赖性 APD 恢复并不是交替存在的必要机制。能够对 DI 进行明确控制，提供了一种将奥特那机制剖析为恢复依赖型和恢复独立型效应的新方法。
Diastolic Intervals and Alternans of APD. Introduction: Investigation of relationship between diastolic-interval (DI)-dependent restitution of action potential duration (APD) and alternans of APD has produced conflicting results. We used a novel pacing protocol to determine the role of restitution in alternans by minimizing changes in DI preceding each activation.Methods: Transmembrane potentials were recorded from right ventricular endocardial tissue isolated from five dogs. We used three pacing sequences: (i) The tissue was paced at a constant DI for 100 beats. (ii) The DIs were changed randomly between two sequences of constant DI. (iii) Each constant DI trial was followed by constant cycle length trial where pacing cycle length was equal to average cycle length during previous constant DI trial.Results: Alternans of APD occurred even when DIs preceding each activation were invariant. Slopes of restitution during constant DI pacing were both negative and positive and were much larger than unity. Alternans amplitude during constant cycle length pacing was larger than during constant DI, 32.2 +/- 12.3 versus 7.5 +/- 2.8 msec, P < 0.01. Random perturbation of DI decreased alternans amplitude during constant DI pacing from 14.7 +/- 4.8 to 10.5 +/- 3.4 msec, P < 0.01.Conclusion: Our results indicate that mechanism of repolarization alternans has restitution-dependent and restitution-independent components. However, our results also provide direct evidence that shows that DI-dependent restitution of APD is not a necessary mechanism for the alternans to exist. Ability to pace with explicit control of DI provides a novel approach to dissect mechanisms of alternans into restitution-dependent and restitution-independent effects.