Profile and kinetics of L-type calcium current during the cardiac ventricular action potential compared in guinea-pigs, rats and rabbits
Profile and kinetics of L-type calcium current during the cardiac ventricular action potential compared in guinea-pigs, rats and rabbits
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DOI：
10.1007/s004240050982
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发表时间：
2000-03-01
影响因子：
4.5
通讯作者：
Meyer, R
中科院分区：
文献类型：
--
作者：
Linz, KW;Meyer, R
哺乳动物心脏动作电位（APs）的物种间差异主要归因于K+电流的变化。在豚鼠、家兔和大鼠离体心室肌细胞的对比研究中，我们研究了基于物种的AP差异对l型Ca2+电流（I-Ca.L）时间过程的影响。此外，我们还测试了I-Ca是否也具有物种依赖性。在膜片钳测量中，I-Ca。L的特征是使用传统的方形脉冲和数字化ap作为命令电压。特别感兴趣的是对I-Ca的实际时间课程的分析。L，以及ap过程中L型通道的激活和失活。虽然AP形态的物种特异性差异强烈影响I-Ca的振幅和时间过程。L型通道失活也存在分化。在每个物种中I-Ca。L失活与Ca2+通过L型通道内流有关。然而，l型通道在家兔和大鼠中表现出相似的Ca2+依赖性。在豚鼠中，2倍高的Ca2+内流是达到一定程度失活所必需的。因此，I-Ca的失活。L在豚鼠中被延迟，从而导致该物种的AP平台期延长。比较I-Ca的实际时间过程。L和L型通道的激活和失活表明，在每个物种中。I-Ca的褪色最终重极化期间的L是由失活（即通道d门关闭）而不是失活引起的。
The substantial interspecies differences in mammalian cardiac action potentials (APs) are attributed primarily to variations in K+ currents. In a comparative study On isolated ventricular myocytes from guinea-pigs, rabbits and rats, we investigated the influence of the species-based AP differences on the time course of the L-type Ca2+ current (I-Ca.L). In addition, we tested whether also species-dependent properties of the I-Ca.L contribute to its time course during the AP. In patch-clamp measurements, I-Ca.L was characterised using conventional square pulses and digitised APs as command voltages. Special interest was directed to the analysis of the actual time courses of I-Ca.L, and L-type channel activation and inactivation during APs. Although species-specific differences in AP shape strongly influence the amplitude and the time course of I-Ca.L, divergence in L-type channel inactivation was found as well. In each species I-Ca.L inactivation was related to Ca2+ influx via L-type channels. However, while L-type channels showed similar Ca2+ dependency in the rabbit and the rat. a 2-times higher Ca2+ influx was necessary to achieve a given degree of inactivation in the guinea-pig. Thus, inactivation of I-Ca.L is delayed in the guinea-pig, thereby contributing to the prolonged AP plateau in this species. Comparing the actual time course of I-Ca.L, and L-type channel activation and inactivation revealed that, in each species. fading of I-Ca.L during final repolarisation was caused by deactivation (i.e. closure of the channel's d-gate) rather than inactivation.