Litovitz T A, Penafiel M, Krause D, Zhang D, Mullins J M
Department of Physics, Catholic University of America, Washington, DC 20064, USA.
Bioelectromagnetics. 1997;18(5):388-95. doi: 10.1002/(sici)1521-186x(1997)18:5<388::aid-bem6>3.0.co;2-z.
Experiments were conducted to see whether the cellular response to electromagnetic (EM) fields occurs through a detection process involving temporal sensing. L929 cells were exposed to 60 Hz magnetic fields and the enhancement of ornithine decarboxylase (ODC) activity was measured to determine cellular response to the field. In one set of experiments, the field was turned alternately off and on at intervals of 0.1 to 50 s. For these experiments, field coherence was maintained by eliminating the insertion of random time intervals upon switching. Intervals < or = 1 s produced no enhancement of ODC activity, but fields switched at intervals > or 10 s showed ODC activities that were enhanced by a factor of approximately 1.7. These data indicate that it is the interval over which field parameters (e.g., amplitude or frequency) remain constant, rather than the interval over which the field is coherent, that is critical to cellular response to an EMF. In a second set of experiments, designed to determine how long it would take for cells to detect a change in field parameters, the field was interrupted for brief intervals (25-200 ms) once each second throughout exposure. In this situation, the extent of EMF-induced ODC activity depended upon the duration of the interruption. Interruptions > or = 100 ms were detected by the cell as shown by elimination of field-induced enhancement of ODC. That two time constants (0.1 and 10 s) are involved in cellular EMF detection is consistent with the temporal sensing process associated with bacterial chemotaxis. By analogy with bacterial temporal sensing, cells would continuously sample and average an EM field over intervals of about 0.1 s (the "averaging" time), storing the averaged value in memory. The cell would compare the stored value with the current average, and respond to the EM field only when field parameters remain constant over intervals of approximately 10 s (the "memory" time).
进行了实验，以探究细胞对电磁场（EM）的反应是否通过涉及时间感知的检测过程发生。将L929细胞暴露于60 Hz磁场中，并测量鸟氨酸脱羧酶（ODC）活性的增强情况，以确定细胞对该磁场的反应。在一组实验中，磁场以0.1至50秒的间隔交替关闭和打开。对于这些实验，通过消除切换时随机时间间隔的插入来保持场相干性。间隔≤1秒时，ODC活性没有增强，但间隔＞10秒切换的磁场显示ODC活性增强了约1.7倍。这些数据表明，对于细胞对电磁场的反应至关重要的是场参数（例如幅度或频率）保持恒定的间隔，而不是场保持相干的间隔。在第二组实验中，为了确定细胞检测场参数变化需要多长时间，在整个暴露过程中，磁场每秒中断一次短暂间隔（25 - 200毫秒）。在这种情况下，电磁场诱导的ODC活性程度取决于中断的持续时间。细胞检测到中断≥100毫秒，这表现为ODC的场诱导增强被消除。细胞电磁场检测涉及两个时间常数（0.1和10秒），这与细菌趋化性相关的时间感知过程一致。类似于细菌时间感知，细胞会在约0.1秒的间隔（“平均”时间）内持续对电磁场进行采样和平均，将平均值存储在记忆中。细胞会将存储的值与当前平均值进行比较，并且仅当场参数在大约10秒的间隔（“记忆”时间）内保持恒定时才对电磁场做出反应。
