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Brain Dynamics: Neural Systems in Space and Time
Published in Ranjit Kumar Upadhyay, Satteluri R. K. Iyengar, Spatial Dynamics and Pattern Formation in Biological Populations, 2021
Ranjit Kumar Upadhyay, Satteluri R. K. Iyengar
Morris and Lecar model [109] is a combination of the Hodgkin–Huxley (HH) and FitzHugh–Nagumo (FHN) models, which considers a voltage-gated calcium channel and a delayed rectifier ionic potassium channel. The model describes the relationship between the membrane voltage and activation of ion channels across the cell membrane. The potential depends on the action of the ion channels (see Figure 6.16). It is a 2D model describing the oscillations in barnacle giant muscle fiber. It is a biophysically plausible model and has measurable parameters. The assumptions made are the following: (i) The equations are based on an isopotential patch of membrane, (ii) calcium ions carry the depolarizing current, (iii) potassium ions carry the hyperpolarizing current, and (iv) ionic conductance for different ionic species relaxes quickly to the steady-state condition which is independent of voltage. The neuron model is described by the following equations (Morris and Lecar [109]):
Musculoskeletal Effects and Applications of Electromagnetic Fields
Published in Ben Greenebaum, Frank Barnes, Biological and Medical Aspects of Electromagnetic Fields, 2018
As for EMF interaction mechanisms, the molecular targets have been refined somewhat although intracellular calcium remains key. Pilla, Brighton, and others have left us several excellent hypotheses (Pilla, 2006, 2015). The shifting of ions, molecules, or receptors by the induced electric fields is thought to modulate binding kinetics along key cellular pathways. The plasma membrane voltage-gated calcium channel (VGCC) and intracellular Ca/calmodulin binding are prime suspects. The activation of nitric oxide and reactive oxygen species (ROS) are more recent findings, considered rapid second messengers. The ability of EMFs to modulate inflammation pathways is also a remarkable development. Changes appear to be able to occur rapidly (0.1 s to several min.) although older evidence exists that EMF exposure effects on Ca fluxes can persist for a day or two in vivo (Spadaro and Bergstrom, 2002). Certainly, other targets are possible. Current evidence seems to suggest that EMF is a rather “blunt instrument” at present and most of the reviewers felt that more investigation of the basic mechanisms is sorely needed.
Geomagnetic Field Effects on Living Systems
Published in Shoogo Ueno, Tsukasa Shigemitsu, Bioelectromagnetism, 2022
Recently, in the case of the birds, Nimpf et al. (2019) suggested that a putative mechanism of magnetoreception by EM induction in the pigeon inner ear. Nimpf et al. (2019) reported the presence of a splice isoform of a voltage-gated calcium channel (CaV1.3) in the pigeon inner ear that has been shown to mediate electroreception in skates and sharks (Bellono et al., 2018). Nimpf et al. (2019) proposed that pigeons detect MFs by EM induction within the semicircular canals that are dependent on the presence of apically located voltage-gated cation channels in a population of electrosensory hair cells.
Responsiveness of voltage-gated calcium channels in SH-SY5Y human neuroblastoma cells on micropillar substrates
Published in Journal of Biomaterials Science, Polymer Edition, 2018
Wenxu Wang, Donghuo Zhong, Yu Lin, Rong Fan, Zhengjun Hou, Xiumei Cao, Yubin Ren
Calcium inward current through the activation of voltage-gated calcium channels (VGCCs) can result in muscular contraction, release of hormones, excitation of neurons, regulation of gene expression, etc. [6–8]. These channels tend to be the target channels used in the treatment of hypertension, angina pectoris, arrhythmia, myocardial infarction, atherosclerosis, cerebral ischemia and stroke, epilepsy, migraine, pancreatitis, chronic neuropathic pain, senile dementia, etc. Critical to the development of a cell-based drug screening system targeting VGCCs is the evaluation of the VGCC functionality. Martinez-Pinna et al. [9] demonstrated that dissociated sympathetic neurons from an adult mouse exhibited lower VGCC response magnitudes, compared with the intact neurons in petri dishes. Lai et al. [10] demonstrated that VGCC responsiveness in neural cells from the superior cervical ganglion of mice was the same for 3D-cultured and freshly dissected cells but significantly higher for flat-cultured cells. Langton [11] shows that the calcium current through VGCC in isolated myocytes from a rat basilar artery was sensitive to stretch. Changes in osmolality could also modulate the calcium current through VGCC in trigeminal ganglion neurons [12]. These findings suggested that the responsiveness of VGCC is strongly affected by extracellular mechanics and that the platform established for VGCC drug screening was significant and necessary.