Huang Feiran, Rabson David, Chen Wei
Department of Physics, University of South Florida, Tampa, Florida 33620, USA.
J Phys Chem B. 2009 Jun 11;113(23):8096-102. doi: 10.1021/jp8054153.
Because of structural independence of the Na/K pump molecules, the pumping rates of individual pumps may not be the same, instead showing some sort of distribution. Detailed information about the distribution has not previously been reported. The pumping rate of Na/K pumps depends on many parameters, such as membrane potential, temperature, and ion concentration gradients across the cell membrane. Fluctuation of any of the variables will change the pumping rate, resulting in a distribution. On the basis of a simplified six-state model, a steady-state pumping flux and therefore the pumping rate were obtained. Parameters were determined based on previous experimental results on amphibian skeletal muscle and theoretical work. Gaussian fluctuations of all the variables were considered to determine the changes in the pumping rate. These variable fluctuations may be totally independent or correlated to each other. The results showed that the pumping rates of the Na/K pumps are distributed in an asymmetric profile, which has a higher probability at the lower pumping rate. We present a model distribution of pumping rates as a function of temperature, membrane potential, and ion concentration.
由于钠钾泵分子的结构独立性，单个泵的泵浦速率可能不尽相同，而是呈现出某种分布。此前尚未有关于该分布的详细信息报道。钠钾泵的泵浦速率取决于许多参数，如膜电位、温度以及跨细胞膜的离子浓度梯度。任何一个变量的波动都会改变泵浦速率，从而导致分布的产生。基于一个简化的六态模型，得出了稳态泵浦通量以及泵浦速率。参数是根据先前关于两栖动物骨骼肌的实验结果和理论研究确定的。考虑了所有变量的高斯波动以确定泵浦速率的变化。这些变量波动可能完全独立，也可能相互关联。结果表明，钠钾泵的泵浦速率呈不对称分布，在较低泵浦速率时具有更高的概率。我们给出了作为温度、膜电位和离子浓度函数的泵浦速率模型分布。
