Braiman A, Gold'Shtein V, Priel Z
Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva, 84105, Israel.
J Theor Biol. 2000 Sep 7;206(1):115-30. doi: 10.1006/jtbi.2000.2104.
In electrically non-excitable cells the predominant mode of calcium signaling is a biphasic rise in cytosolic calcium concentration. It results from Ca(2+)release from intracellular stores, followed by Ca(2+)influx across the plasma membrane. It has been hypothesized that prolonged calcium influx may result in a sustained local elevation of the cytosolic calcium concentration near the plasma membrane. The mathematical model presented here evaluates the cytosolic concentration of Ca(2+)as a function of time and distance from the plasma membrane. It consists of cytoplasmic calcium stores and a plasma membrane, both equipped with calcium channels and pumps, and an immobile cytoplasmic calcium buffer. The model has verified quantitatively the feasibility of a stable Ca(2+)gradient in the cytosol with high values of Ca(2+)concentration near the plasma membrane and evaluated its properties as a function of different cellular parameters. The formation of the gradient does not require special distribution of the intracellular contents, channels and pumps. However, it requires buffering of the cytosolic calcium by the intracellular stores and that the rate of calcium release from the stores near the plasma membrane be higher than in other parts of the cell. We suggest that this model can provide an adequate description of the elevated calcium plateau generally observed in electrically non-excitable cells.
在电非兴奋性细胞中，钙信号传导的主要模式是胞质钙浓度的双相升高。它源于细胞内钙库释放Ca(2+)，随后Ca(2+)通过质膜流入。据推测，长时间的钙流入可能导致质膜附近胞质钙浓度持续局部升高。这里提出的数学模型评估了Ca(2+)的胞质浓度随时间和距质膜距离的变化。它由细胞质钙库和质膜组成，两者都配备有钙通道和泵，以及一个固定的细胞质钙缓冲剂。该模型已定量验证了胞质溶胶中稳定Ca(2+)梯度的可行性，质膜附近Ca(2+)浓度较高，并评估了其作为不同细胞参数函数的特性。梯度的形成不需要细胞内成分、通道和泵的特殊分布。然而，它需要细胞内钙库对胞质钙进行缓冲，并且质膜附近钙库的钙释放速率要高于细胞其他部位。我们认为该模型可以充分描述电非兴奋性细胞中普遍观察到的钙平台升高现象。
