Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 105, 1113, Sofia, Bulgaria.
Pflugers Arch. 2023 Sep;475(9):1113-1128. doi: 10.1007/s00424-023-02838-4. Epub 2023 Jul 19.
In this study, a new idea that electrogenic transporters determine cell resting state is presented. The previous assumption was that pumps, especially the sodium one, determine it. The latter meets difficulties, because it violates the law of conservation of energy; also a significant deficit of pump activity is reported. The amount of energy carried by a single ATP molecule reflects the potential of the inner mitochondrial membrane, which is about -200 mV. If pumps enforce a resting membrane potential that is more than twice smaller, then the majority of energy stored in ATP would be dissipated by each pump turning. However, this problem could be solved if control is transferred from pumps to something else, e.g., electrogenic transporters. Then pumps would transfer the energy to the ionic gradient without losses, while the cell surface membrane potential would be associated with the reversal potential of some electrogenic transporters. A minimal scheme of this type would include a sodium-calcium exchanger as well as sodium and calcium pumps. However, note that calcium channels and pumps are positioned along both intracellular organelles and the surface membrane. Therefore, the above-mentioned scheme would involve them as well as possible intercellular communications. Such schemes where various kinds of pumps are assumed to work in parallel may explain, to a great extent, the slow turning rate of the individual members. Interaction of pumps and transporters positioned at distant biological membranes with various forms of energy transfer between them may thus result in hypoxic/reperfusion injury, different kinds of muscle fatigue, and nerve-glia interactions.
在这项研究中，提出了一个新的观点，即电致离子转运体决定细胞的静息状态。之前的假设是泵，特别是钠泵，决定了细胞的静息状态。但这种假设存在困难，因为它违反了能量守恒定律；此外，据报道泵的活性存在显著不足。单个 ATP 分子所携带的能量反映了线粒体内膜的势能，约为-200 mV。如果泵产生的静息膜电位小于这个值的两倍，那么每个泵旋转所消耗的能量将超过储存在 ATP 中的大部分能量。然而，如果这种控制从泵转移到其他物质（例如电致离子转运体），则可以解决这个问题。然后，泵将能量转移到离子梯度中，而不会有任何损失，同时细胞表面膜电位将与某些电致离子转运体的反转电位相关联。这种类型的最小方案将包括钠钙交换体以及钠泵和钙泵。然而，请注意，钙通道和泵沿着细胞内细胞器和表面膜分布。因此，上述方案将涉及它们以及可能的细胞间通讯。这种假设各种泵平行工作的方案可以在很大程度上解释单个成员的缓慢转动速率。位于不同生物膜上的泵和转运体之间的相互作用，以及它们之间各种形式的能量转移，可能导致缺氧/再灌注损伤、不同类型的肌肉疲劳和神经胶质相互作用。
