| With the advancement of technology,the influence of electromagnetic fields,especially low-frequency low-intensity electromagnetic fields(LF_EMF)on the human body,has attracted more and more attention.Low-frequency low-intensity electromagnetic fields are often applied in clinical medicine to treat neurological diseases.And magnetic fields have been shown to regulate ion channels.The transmission of information between neurons is mainly reflected by the discharge of different patterns of nerve fibers,so membrane potential is an important indicator of cell electrophysiological activity.In the past studies,it is generally believed that the change of cell transmembrane potential induced by magnetic field induced electric field is the main factor that regulates the electrical activity of ion channel,and whether this factor is also the main factor affects cell electrical activity of LF_EMF is lack of verification.This paper uses the combination of theory and experiment to complete the research work of this subject.Since the induced electric field is regarded as the cause of the membrane potential change influenced by the low-frequency low-intensity electromagnetic field,this paper starts with the electric field induced membrane potential.In the past,the electric field induced changes in transmembrane potential,generally only consider the role of isolated neurons,but in fact the cells are closely arranged and interacted with each other,so this paper first analyzes the interaction between the two cells under the electric field.Membrane potential changes,and the effects of different positions between cells and cell radius and conductivity on transmembrane potential changes were analyzed.It was found that the electric field of 104V/m can induce membrane potential changes of mV level.Then,the magnetic stimulation of the hippocampal CA1 pyramidal cells in vitro was performed by online magnetic stimulation device for 30 min.The Na+ and K+ channel currents were recorded by patch clamp technique.The maximum current density of the ion channel and the maximum channel conductance and membrane potential will change under the low-frequency low-intensity magnetic field with different parameters in the experiments.It is found by data analysis that the low-frequency low-intensity magnetic field of the mT level can cause the transmembrane potential change of the mV level.In order to further verify the mechanism of LF_EMF induced transmembrane potential changes,this paper uses COMSOL software to simulate the magnetic field and induced electric field changes in the CAl region of hippocampal slices under the experimental magnetic field parameters.It is found that the maximum induced electric field generated by the experimental dose of magnetic field is only On the order of 10-3 V/m,and the membrane potential change is only 10-5 mV.It can be seen from the simulation analysis that the membrane potential of this magnitude is insufficient to cause the electrical activity of the ion channel of the excited cell.Therefore,this paper speculates that low-frequency low-intensity magnetic fields may change the conversion probability of Na+ and K+ channels that in turn affects cell transmembrane potential and ion channel electrical activity.Through the two-state channel model and the HH model,the combination of simulation and theory proves that LF_EMF can change the ion channel transition probability,which affects the channel conductance and changes the cell membrane potential.At the same time,the membrane potential can counteract the ion-gated variable and regulate the ion channel transition probability.The guess mentioned before is vertified.On this basis,the changes in cell membrane potential were analyzed when the current was added and the conductivity outside the membrane was changed.The research work in this paper has important research significance for further explaining the mechanism of action of LF EMF on cell transmembrane potential. |
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