Tang Y, Othmer H G
Department of Mathematics, University of Utah, Salt Lake City 84112.
Biophys J. 1994 Dec;67(6):2223-35. doi: 10.1016/S0006-3495(94)80707-6.
The ryanodine-sensitive calcium channels are pivotal to signal transduction and cell function in many cell types, including cardiac myocytes. In this paper a kinetic model is proposed for these channels. In the model there are two Ca regulatory sites on the channel protein, one positive and the other negative. Cytoplasmic Ca binds to these regulatory sites independently It is assumed that the binding of Ca to the positive site is a much faster process than binding to the negative site. At steady state, the channel opening as a function of the Ca concentration is a bell-shaped curve. The model predicts the adaptation of channels to constant Ca stimulus. When this model is applied to cardiac myocytes, it predicts excitability with respect to Ca perturbations, smoothly graded responses, and Ca oscillations in certain pathological circumstances. In a spatially distributed system, traveling Ca waves in individual myocytes exist under certain conditions. This model can also be applied to other systems where the ryanodine-sensitive channels have been identified.
包括心肌细胞在内，许多细胞类型中对兰尼碱敏感的钙通道在信号转导和细胞功能方面起着关键作用。本文针对这些通道提出了一个动力学模型。在该模型中，通道蛋白上有两个钙调节位点，一个是正性的，另一个是负性的。细胞质钙独立地与这些调节位点结合。假定钙与正性位点的结合过程比与负性位点的结合快得多。在稳态下，通道开放作为钙浓度的函数是一条钟形曲线。该模型预测了通道对恒定钙刺激的适应性。当将此模型应用于心肌细胞时，它预测了对钙扰动的兴奋性、平滑分级反应以及某些病理情况下的钙振荡。在一个空间分布系统中，在某些条件下单个心肌细胞中会存在传播的钙波。该模型也可应用于已鉴定出对兰尼碱敏感通道的其他系统。
