Scaiano J C, Cozens F L, Mohtat N
Department of Chemistry, University of Ottawa, Ontario, Canada.
Photochem Photobiol. 1995 Nov;62(5):818-29. doi: 10.1111/j.1751-1097.1995.tb09142.x.
The effect of an alternating current (AC) magnetic field (MF) on radical behavior is identical to that exerted by a direct current (DC) field of the same instantaneous strength provided that the frequency is low enough in comparison with radical pair dynamics. This criterion is easily met by environmental fields. In general, combined AC/DC fields will lead to increased radical concentrations and oscillating free radical concentrations. Interestingly, the frequency of oscillation for radical concentration seldom follows exactly the pattern of the external AC component of the MF. Even the simple case of an AC-only field at 60 Hz can lead to oscillations in radical concentrations at 120 Hz. The concentration time dependence patterns can be even more complex when the singlet and triplet levels of the radical pair are not degenerate. Further, the effects can change dramatically depending upon the absolute and relative values of the AC and DC components, thus providing a possible explanation for MF windows for certain effects reported experimentally. Effects on the average radical concentration are probably relevant only for fields higher than about 0.1 gauss. Oscillating radical concentrations may influence signal transduction processes or other cellular mechanisms; at the present time there is not enough knowledge available to establish a reasonable threshold for these types of effects. This contribution aims at providing a solid foundation to guide the experimentalist in the design of meaningful experiments on the possible role of MF perturbations of radical chemistry on biological response.
如果与自由基对动力学相比频率足够低，那么交变电流（AC）磁场（MF）对自由基行为的影响与相同瞬时强度的直流（DC）场的影响相同。环境场很容易满足这一标准。一般来说，AC/DC组合场会导致自由基浓度增加以及自由基浓度振荡。有趣的是，自由基浓度的振荡频率很少完全遵循MF外部AC分量的模式。即使是60 Hz的纯AC场这种简单情况，也会导致自由基浓度以120 Hz振荡。当自由基对的单重态和三重态能级不简并时，浓度随时间的依赖模式可能会更加复杂。此外，根据AC和DC分量的绝对值和相对值，影响可能会发生巨大变化，从而为实验报道的某些效应的MF窗口提供了一种可能的解释。对平均自由基浓度的影响可能仅在高于约0.1高斯的场中才相关。振荡的自由基浓度可能会影响信号转导过程或其他细胞机制；目前还没有足够的知识来为这些类型的效应确定一个合理的阈值。本论文旨在提供一个坚实的基础，以指导实验人员设计关于自由基化学的MF扰动对生物反应可能作用的有意义的实验。
