The local calcium concentration in the active zone of secretion determines the number and kinetics of neurotransmitter quanta released after the arrival of a nerve action potential in chemical synapses. The small size of mammalian neuromuscular junctions does not allow direct measurement of the correlation between calcium influx, the state of endogenous calcium buffers determining the local concentration of calcium and the time course of quanta exocytosis. In this work, we used computer modeling of quanta release kinetics with various levels of calcium influx and in the presence of endogenous calcium buffers with varying mobilities. The results of this modeling revealed the desynchronization of quanta release under low calcium influx in the presence of an endogenous fixed calcium buffer, with a diffusion coefficient much smaller than that of free Ca(2+), and synchronization occurred upon adding a mobile buffer. This corresponds to changes in secretion time course parameters found experimentally (Samigullin et al., Physiol Res 54:129-132, 2005; Bukharaeva et al., J Neurochem 100:939-949, 2007).

中文翻译：

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在固定和移动钙缓冲液存在下模拟量子神经递质释放动力学。

分泌活动区的局部钙浓度决定了化学突触中神经动作电位到达后释放的神经递质量子的数量和动力学。哺乳动物神经肌肉接头的小尺寸不允许直接测量钙流入、决定局部钙浓度的内源性钙缓冲液的状态和量子胞吐作用的时间过程之间的相关性。在这项工作中，我们使用了具有不同钙流入水平和具有不同迁移率的内源性钙缓冲液的量子释放动力学的计算机建模。该模型的结果揭示了在存在内源性固定钙缓冲液的情况下，在低钙流入下量子释放的去同步化，具有远小于游离 Ca(2+) 的扩散系数，并且在添加移动缓冲区时发生同步。这对应于实验发现的分泌时间进程参数的变化（Samigullin 等人，Physiol Res 54:129-132, 2005；Bukharaeva 等人，J Neurochem 100:939-949, 2007）。