Spark-to-wave transition: saltatory transmission of calcium waves in cardiac myocytes
Spark-to-wave transition: saltatory transmission of calcium waves in cardiac myocytes
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DOI：
10.1016/s0301-4622(98)00125-2
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发表时间：
1998-05-05
影响因子：
3.8
通讯作者：
Smith, GD
中科院分区：
文献类型：
--
作者：
Keizer, J;Smith, GD
使用模块化的方法，其中细胞中钙处理的各种机制的动力学模型被微调到体内和体外测量，然后将它们组合成全细胞模型，三种不同的钙波在成熟和未成熟的青蛙卵中的传输模式已被定义。在未成熟卵中发现两种传递模式，其中肌醇1，4，5-三磷酸受体（IP 3R）控制钙从内质网（ER）的释放。第一种模式对应于细胞质的可激发生理状态，并导致孤立波，其可以在二维中表现为圆形或螺旋波，其波速与钙的扩散常数的平方根成比例。当细胞质的状态是振荡的并且由于钙的缓冲扩散常数的小尺寸时，第二模式发生，波速可以表现为弱地依赖于扩散。在成熟的青蛙卵中，精子诱导的Ca 2+受精波是一个传播前沿，细胞质似乎是透明的，在这种模式下，波速也与扩散常数的平方根成正比。在这里，我们调查的第四种模式的心肌细胞的传播，其中钙从肌浆网（SR）的释放是占主导地位的集群的兰尼碱受体间隔定期。在肌细胞中，随机可兴奋的肌浆导致钙“火花”的自发产生，在某些条件下，钙“火花”可以以与扩散常数成比例的速度合并成跳跃波。(C)1998 Elsevier Science B. V.保留所有权利。
Using a modular approach, in which kinetic models of various mechanisms of calcium handling in cells are fine-tuned to in vivo and in vitro measurements before combining them into whole-cell models, three distinct modes of transmission of calcium waves in mature and immature frog eggs have been defined. Two modes of transmission are found in immature eggs, where the inositol 1,4,5-trisphosphate receptor (IP3R) controls release of calcium from the endoplasmic reticulum (ER). The first mode corresponds to an excitable physiological state of the cytoplasm and results in solitary waves that can appear as circular or spiral waves in two dimensions with the wave speed proportional to the square root of the diffusion constant of calcium. A second mode occurs when the state of the cytoplasm is oscillatory and because of the small size of the buffered diffusion constant for calcium, the wave speed can appear to be weakly dependent on diffusion. In the mature frog egg, where the sperm-induced Ca2+ fertilization wave is a propagating front, the cytoplasm appears to be bistable and in this mode the wave speed is also proportional to the square root of the diffusion constant. Here we investigate a fourth mode of propagation for cardiac myocytes, in which calcium release from the sarcoplasmic reticulum (SR) is dominated by clusters of ryanodine receptors spaced at regular intervals. In myocytes a stochastically excitable myoplasm leads to the spontaneous production of calcium 'sparks' that under certain conditions can merge into saltatory waves with a speed proportional to the diffusion constant. (C) 1998 Elsevier Science B.V. All rights reserved.