Toronto Western Research Institute, University Health Network, Ontario, Canada .
J Neuroeng Rehabil. 2010 Feb 20;7:12. doi: 10.1186/1743-0003-7-12.
When a cell is exposed to a time-varying magnetic field, this leads to an induced voltage on the cytoplasmic membrane, as well as on the membranes of the internal organelles, such as mitochondria. These potential changes in the organelles could have a significant impact on their functionality. However, a quantitative analysis on the magnetically-induced membrane potential on the internal organelles has not been performed.
Using a two-shell model, we provided the first analytical solution for the transmembrane potential in the organelle membrane induced by a time-varying magnetic field. We then analyzed factors that impact on the polarization of the organelle, including the frequency of the magnetic field, the presence of the outer cytoplasmic membrane, and electrical and geometrical parameters of the cytoplasmic membrane and the organelle membrane.
The amount of polarization in the organelle was less than its counterpart in the cytoplasmic membrane. This was largely due to the presence of the cell membrane, which "shielded" the internal organelle from excessive polarization by the field. Organelle polarization was largely dependent on the frequency of the magnetic field, and its polarization was not significant under the low frequency band used for transcranial magnetic stimulation (TMS). Both the properties of the cytoplasmic and the organelle membranes affect the polarization of the internal organelle in a frequency-dependent manner.
The work provided a theoretical framework and insights into factors affecting mitochondrial function under time-varying magnetic stimulation, and provided evidence that TMS does not affect normal mitochondrial functionality by altering its membrane potential.
当细胞暴露于时变磁场中时，这会导致细胞质膜以及内部细胞器（如线粒体）的膜上产生感应电压。这些细胞器中的电位变化可能对其功能产生重大影响。然而，尚未对细胞器中磁诱导膜电位进行定量分析。
使用双壳模型，我们提供了用于时变磁场诱导细胞器膜内跨膜电位的第一个解析解。然后，我们分析了影响细胞器极化的因素，包括磁场的频率、外细胞质膜的存在以及细胞质膜和细胞器膜的电学和几何参数。
细胞器的极化量小于细胞质膜的极化量。这主要是由于细胞膜的存在，它通过磁场“屏蔽”了细胞器的过度极化。细胞器的极化主要取决于磁场的频率，而在用于经颅磁刺激（TMS）的低频带中，其极化不明显。细胞质膜和细胞器膜的性质都以频率依赖的方式影响内部细胞器的极化。
该工作为研究时变磁场刺激下影响线粒体功能的因素提供了理论框架和见解，并提供了证据表明 TMS 通过改变其膜电位不会影响正常的线粒体功能。
