Moderate-intensity Static Magnetic Field Research Articles

Osteogenic differentiation of MC3T3-E1 cells on poly(L-lactide)/Fe3O4 nanofibers with static magnetic field exposure.

Proliferation and differentiation of bone-related cells are modulated by many factors such as scaffold design, growth factor, dynamic culture system, and physical simulation. Nanofibrous structure and moderate-intensity (1 mT-1 T) static magnetic field (SMF) have been identified as capable of stimulating proliferation and differentiation of osteoblasts. Herein, magnetic nanofibers were prepared by electrospinning mixture solutions of poly(L-lactide) (PLLA) and ferromagnetic Fe3O4 nanoparticles (NPs). The PLLA/Fe3O4 composite nanofibers demonstrated homogeneous dispersion of Fe3O4 NPs, and their magnetism depended on the contents of Fe3O4 NPs. SMF of 100 mT was applied in the culture of MC3T3-E1 osteoblasts on pure PLLA and PLLA/Fe3O4 composite nanofibers for the purpose of studying the effect of SMF on osteogenic differentiation of osteoblastic cells on magnetic nanofibrous scaffolds. On non-magnetic PLLA nanofibers, the application of external SMF could enhance the proliferation and osteogenic differentiation of MC3T3-E1 cells. In comparison with pure PLLA nanofibers, the incorporation of Fe3O4 NPs could also promote the proliferation and osteogenic differentiation of MC3T3-E1 cells in the absence or presence of external SMF. The marriage of magnetic nanofibers and external SMF was found most effective in accelerating every aspect of biological behaviors of MC3T3-E1 osteoblasts. The findings demonstrated that the magnetic feature of substrate and microenvironment were applicable ways in regulating osteogenesis in bone tissue engineering.

Effects of moderate intensity static magnetic fields on human bone marrow-derived mesenchymal stem cells.

This study aimed to explore effects of static magnetic fields (SMFs) of moderate intensity (3-50 mT) as biophysical stimulators of proliferation and osteoblastic differentiation of human bone marrow-derived mesenchymal stem cells (MSCs). MSCs were exposed to SMFs of three intensities: 3, 15, and 50 mT. Proliferation was assessed by cell counting and bromodeoxyuridine incorporation, and differentiation by measuring alkaline phosphatase (ALP) activity, calcium content, mineralized nodule formation, and transcripts of osteogenic markers. Moderate intensity SMFs increased cell proliferation, ALP activity, calcium release, and mineralized nodule formation in a dose- and time-dependent manner, which peaked at 15 mT. In the same manner, they upregulated expression of osteogenic marker genes such as ALP, bone sialoprotein 2 (BSP2), collagen1a1 (COL1a1), osteocalcin (OCN), osteonectin (ON), osteopontin (OPN), osterix (OSX), and runt-related transcription factor 2 (RUNX2) with peak at 15 mT after 14 or 21 days of exposure. Results demonstrate that moderate intensity SMFs promote proliferation and osteoblastic differentiation of MSCs. This effect could help to improve MSC responses during osseointegration between a dental implant and surrounding bone.

Decreased P-glycoprotein is associated with the inhibitory effects of static magnetic fields and cisplatin on K562 cells.

In this study, we explored the mechanism of the killing effects of a moderate-intensity static magnetic field (SMF) and cisplatin (DDP) on K562 cells. We analyzed the metabolic activity of cells, the extracellular DDP content, and P-glycoprotein (P-gp) expression after K562 cells were exposed continuously to a uniform 8.8 mT SMF for 8 h, with or without DDP. We found that SMF combined with DDP (10 µg/ml) significantly inhibited the metabolic activity of K562 cells (P < 0.05), while neither DDP nor SMF alone affected the metabolic activity of these cells. In the SMF + DDP group, extracellular DDP content was significantly reduced (P < 0.05). DDP also induced the expression of P-gp (P < 0.05). By contrast, in the SMF + DDP group, P-gp expression decreased compared with the DDP group (P < 0.05). Taken together, our results showed that 8.8 mT SMF enhanced the killing potency of DDP on K562 cells by decreasing the expression of P-gp.

Effects of moderate static magnetic fields on the voltage-gated sodium and calcium channel currents in trigeminal ganglion neurons

Aim: To study the effects of static magnetic fields (SMF) on the electrophysiological properties of voltage-gated sodium and calcium channels on trigeminal ganglion (TRG) neurons. Methods: Acutely dissociated TRG neurons of neonatal SD rats were exposed to 125-mT and 12.5-mT SMF in exposure devices and whole-cell patch-clamp recordings were carried out to observe the changes of voltage-gated sodium channels (VGSC) and calcium channels (VGCC) currents, while laser scanning confocal microscopy was used to detect intracellular free Ca2+ concentration in TRG neurons, respectively. Results: (1) No obvious change of current–voltage (I–V) relationship and the peak current densities of VGSC and VGCC currents were found when TRG neurons were exposed to 125-mT and 12.5-mT SMF. However, the activation threshold, inactivation threshold and velocity of the channel currents above were significantly altered by 125-mT and 12.5-mT SMF. (2) The fluctuation of intracellular free Ca2+ concentration within TRG neurons were slowed by 125-mT and 12.5-mT SMF. When SMF was removed, the Ca2+ concentration level showed partial recovery in the TRG neurons previously exposed by 125-mT SMF, while there was a full recovery found in 12.5-mT-SMF-exposed neurons. Conclusions: Moderate-intensity SMF could affect the electrophysiological characteristics of VGCS and VGCC by altering their activation and inactivation threshold and velocity. The fluctuations of intracellular free Ca2+ caused by SMF exposure were not permanent in TRG neurons.

Effects of sub-chronic exposure to moderate intensity static magnetic field (SMF) on oxidative stress parameters of male rats

Increasing exposure to electromagnetic fields has become inevitable for people living in industrialized environments. Magnetic fields can increase the production of free radicals; reports also suggest that extremely low frequency magnetic fields (ELF-MF) can increase free radical life-span. This study evaluated the effects of moderate intensity static magnetic field (SMF) (56 Hz, 41 mT, 6 h/day) on the oxidative status of male rats. Plasma and tissue (liver, heart, kidney, brain and testes) superoxide dismutase (SOD) and catalase (CAT) activities, as well as malondialdehyde (MDA) concentrations were measured after 35 consecutive days of exposure to the SMF. SMF exposure caused significant reductions in the body weight of rats but did not alter relative organ weight. Plasma and tissue MDA concentration were statistically insignificantly reduced, tissue SOD activities were slightly increased, while plasma and liver CAT activities were significantly (p<0.05) increased in SMF exposed rats. The conditions of our study show that while an oxidative challenge was experienced by the rats exposed to SMF, oxidative stress did not occur. Higher intensity SMF and/or longer duration of exposure may however lead to oxidative stress. Key words: Static magnetic field, oxidative stress, superoxide dismutase, catalase, malondialdehyde.

Evaluation of the Effects of a Moderate Intensity Static Magnetic Field Application on Human Osteoblast-Like Cells

There is a general interest in the effects of magnetic fields on human tissue, for biomedical imaging, cancer therapy or tissue engineering applications. In particular the orthopaedic field may greatly benefit from magnetic scaffolds, magnetic fixation and magnetic delivery techniques. In this study, MG-63 osteoblast-like cells were analysed <i>in vitro</i> after exposure to a 320mT static magnetic field (SMF), either continuously or applied for 1h at any 24-hour interval. Results demonstrate that SMF causes a reduction in cell number after 7 days of exposure, as demonstrated by the MTT assay. This reduction in proliferation is not associated to an increase in Lactate Dehydrogenase production, a marker of cellular stress and/or disruption of membrane integrity. Osteocalcin secretion increased at day 3 for the condition 1h/day exposure and this effect was reversed after 7 days. Instead, the continuous application of a SMF resulted in a significantly decreased osteocalcin release at day 7. Cell distribution, morphology and cytoskeleton organization were unaltered, with the typical osteoblastic morphology maintained and normal distribution of cytoplasmic actin fibrils, as demonstrated by phalloidin staining. Gene expression analysis of COL1A1, ALPL and RUNX2 show no alterations respect to control. These results suggest that such a moderate intensity static magnetic field has a detrimental effect on cell proliferation and osteocalcin secretion, while maintaining morphological features and gene expression unaltered. The <i>in vitro</i> effects of magnetic fields depend on cell type, magnetic field intensity and modality of application. This study gives a contribution to understand moderate strength static magnetic field effects on human tissue, with particular importance for the orthopaedic field.

Moderate intensity static magnetic field has bactericidal effect on E. coli and S. epidermidis on sintered hydroxyapatite

The application of electromagnetic field in the context of bacteria associated infections on biomaterial surfaces has not been extensively explored. In this work, we applied a moderate intensity static magnetic field (100 mT) to understand the adhesion and growth behavior of both gram positive (S. epidermidis) and gram negative bacteria (E. coli) and also to investigate bactericidal/bacteriostatic property of the applied electromagnetic field. An in-house built magnetometer was used to apply static homogeneous magnetic field during a planned set of in vitro experiments. Both the sintered hydroxyapatite (HA) and the control samples seeded with bacteria were exposed to the magnetic field (100 mT) for different timescale during their log phase growth. Quantitative analysis of the SEM images confirms the effect of electromagnetic field on suppressing bacterial growth. Furthermore, cell integrity and inner membrane permeabilization assays were performed to understand the origin of such effect. The results of these assays were statistically analyzed to reveal the bactericidal effect of magnetic field, indicating cell membrane damage. Under the investigated culture conditions, the bactericidal effect was found to be less effective for S. Epidermidis than E. coli.

A Moderate-Intensity Static Magnetic Field Enhances Repair of Cartilage Damage in Rabbits

Electromagnetic fields have been proposed to enhance healing of cartilage defects by stimulation of chondrocyte proliferation, proteoglycan synthesis as well as decreasing pain and improving motion in osteoarthritic patients. However, the effects of a moderate-intensity static magnetic field on cartilage repair have not been investigated. This study tries to determine the effects of a moderate-intensity permanent magnetic field of 40 mT on cartilage repair. Defects of 3 mm in diameter and 6 mm in depth were made on the weight bearing surface of the right medial femoral condyle of 30 rabbits. The animals were divided randomly into three equal groups (magnet, sham and control). In the magnet group, cylindrical permanent magnets were implanted subcutaneously medial to the medial femoral condyle, while in the sham group the cylindrical ceramic were not magnetized, and nothing was implanted in controls. After 12 weeks of observation, Mankin's microscopic scoring was done on all specimens, and irregularity of surface characteristics, cell colonization, hypocellularity, cartilage matrix formation, and presence of empty lacunae were investigated. Each of these characteristics showed significant differences in magnet group relative to control and sham groups (p <0.05). Mankin's score was 1.6 ± 0.6 in magnet group, 7.2 ± 1.6 in sham group and 7.7 ± 1 in control group (p <0.001). [corrected] In this animal study, microscopic Mankin's scoring depicted histological improvement in cartilage of magnet group.

Is static magnetic field exposure a new model of metabolic alteration? Comparison with Zucker rats

Purpose: The aim of this study was to investigate if the metabolic alterations observed after static magnetic field (SMF) exposure participates in the development of a pre-diabetic state. A comparison study using the insulin resistant animal model, the Zucker rat and the SMF-exposed Wistar rat was carried out.Materials and methods: Zucker rats were compared to Wistar rats either exposed to a 128 mT or 0 mT SMF (sham exposed) and analysed. This moderate-intensity SMF exposure of Wistar rats was performed for 1 h/day during 15 consecutive days.Results: Wistar rats exposed to the SMF showed increased levels of carbohydrate and lipid metabolites (i.e., lactate, glycerol, cholesterol and phospholipids) compared to sham-exposed rats. Zucker rats displayed a normoglycemia associated with a high insulin level as opposed to Wistar rats which presented hyperglycemia and hypoinsulinemia after exposure to the SMF. During the glucose tolerance test, unexposed Zucker rats and Wistar rats exposed to the SMF exhibited a significantly higher hyperglycemia compared to sham-exposed Wistar rats suggesting an impairment of glucose clearance. In muscle, glycogen content was lower and phospholipids content was elevated for both unexposed Zucker rats and Wistar rats exposed to the SMF compared to Wistar rats sham control.Conclusions: This study provides evidence that the metabolic alterations following exposure to a static magnetic field of moderate intensity could trigger the development of a pre-diabetic state.

Clinical aspects of static magnetic field effects on circulatory system

Increased knowledge of the magnetic field influence on hemodynamic function may have significant therapeutic potential and possible health effects. For example, magnetic field therapy using moderate intensity static magnetic fields (SMF) in the mT range (in particular, 1–600 mT) could be useful for circulatory diseases, including ischemic pain, inflammation, and hypertension, primarily due to the modulation of blood flow and/or blood pressure through the nervous system. We suggested that the mechanisms of SMF effects on the circulatory system in the mT range could be mediated by suppressing or enhancing the action of biochemical effectors, thereby inducing homeostatic effects biphasically. The potent mechanisms of SMF effects have often been linked to nitric oxide pathway, Ca2+-dependent pathway, sympathetic nervous system (e.g., BRS and the action of sympathetic agonists or antagonists), and neurohumoral regulatory system (e.g., production and secretion of angiotensin II and aldosterone). Thus, this review mainly focuses on the experimental studies of SMF effects on the circulatory system in animals and may provide the physiological basis for future clinical investigations of SMF therapy.

Effects of a moderate‐intensity static magnetic field and adriamycin on K562 cells

The aim of this study was to investigate whether a moderate-intensity static magnetic field (SMF) can enhance the killing effect of adriamycin (ADM) on K562 cells, and to explore the effects of SMF combined with ADM on K562 cells. We analyzed the metabolic activity of cells, cell cycle distribution, DNA damage, change in cell ultrastructure, and P-glycoprotein (P-gp) expression after K562 cells were exposed continuously to a uniform 8.8 mT SMF for 12 h, with or without ADM. Our results showed that the SMF combined with ADM (25 ng/ml) significantly inhibited the metabolic activity of K562 cells (P < 0.05), while neither ADM nor the SMF alone affected the metabolic activity of these cells. Cell ultrastructure was altered in the SMF + ADM group. For example, cell membrane was depressed, some protuberances were observable, and vacuoles in the cytoplasm became larger. Cells were arrested at the G2/M phase and DNA damage increased after cells were treated with the SMF plus ADM. ADM also induced the P-gp expression. In contrast, in the SMF group and SMF + ADM group, the P-gp expression was decreased compared with the ADM group. Taken together, our results showed that the 8.8 mT SMF enhanced the cytotoxicity potency of ADM on K562 cells, and the decrease in P-gp expression may be one reason underlying this effect.

Recovery Effects of a 180 mT Static Magnetic Field on Bone Mineral Density of Osteoporotic Lumbar Vertebrae in Ovariectomized Rats

The effects of a moderate-intensity static magnetic field (SMF) on osteoporosis of the lumbar vertebrae were studied in ovariectomized rats. A small disc magnet (maximum magnetic flux density 180 mT) was implanted to the right side of spinous process of the third lumbar vertebra. Female rats in the growth stage (10 weeks old) were randomly divided into 4 groups: (i) ovariectomized and implanted with a disc magnet (SMF); (ii) ovariectomized and implanted with a nonmagnetized disc (sham); (iii) ovariectomized alone (OVX) and (vi) intact, nonoperated cage control (CTL). The blood serum 17-β-estradiol (E2) concentrations were measured by radioimmunoassay, and the bone mineral density (BMD) values of the femurs and the lumbar vertebrae were assessed by dual energy X-ray absorptiometry. The E2 concentrations were statistically significantly lower for all three operated groups than those of the CTL group at the 6th week. Although there was no statistical significant difference in the E2 concentrations between the SMF-exposed and sham-exposed groups, the BMD values of the lumbar vertebrae proximal to the SMF-exposed area statistically significantly increased in the SMF-exposed group than in the sham-exposed group. These results suggest that the SMF increased the BMD values of osteoporotic lumbar vertebrae in the ovariectomized rats.

Characteristics of Delayed Rectifier Potassium Channels Exposed to 3 mT Static Magnetic Field

To investigate the characteristics of delayed rectifier potassium channel of cells under moderate intensity static magnetic field, the delayed rectifier potassium channel currents (IK) of acutely isolated mouse prefrontal cortex pyramidal neurons were examined. IK was measured and recorded after the neurons were exposed to 3 mT static magnetic field for 15,30, and 60 min. The results demonstrated that the 3 mT static magnetic field can change the characteristics of delayed rectifier potassium channel and reduce the amplitudes of IK. The maximum activated current densities of control group and 30 min exposure group were respectively 173.61 ± 30.68 pA/pF and 111.80 ± 17.17 pA/pF (n = 10, P <; 0.05). The half-activation voltage of the activation curves changed from -1.08 ± 2.17 mV to 10.63 ± 1.51 mV (n = 10, P <; 0.05) and the slope factor changed from 22.26 ± 2.99 mV to 17.90 ± 1.85 mV (n = 10, P <; 0.05). No change was noted in the inactivation process. The results show that moderate-intensity static magnetic field can change the characteristics of delayed rectifier potassium channel on the cell membrane, and further it may affect the physiological functions of neurons.

Effect of static magnetic field on erythrocytes characterizations

The interaction of static magnetic field (SMF) with living organisms is a rapidly growing field of investigation. Recently, exposure to moderate intensity SMFs (1 mT – 1 T) has attracted much attention for its various medical applications. This study was designed to show the microscopic effect of SMF on erythrocytes in vitro. For this purpose SMF system was constructed in my lab on basis of the idea of cell tracking velocimetry system. The changes in erythrocytes surface area, sphericity, and adhesion number for erythrocytes were calculated to quantify the effect of SMF on erythrocytes characterizations. The results showed that SMF increased erythrocytes surface area and reduced their sphericity. The adhesion number of erythrocytes under the influence of SMF showed the tendency of erythrocytes to adhere with each other. These findings indicate that more study on microscopic scales must be carried out in order to investigate the effect of SMF on erythrocytes.

Differentiation of monocytic U937 cells under static magnetic field exposure

We present here a morphological, cytochemical and biochemical study of the macrophagic differentiation of human pro-monocytic U937 cells exposed to moderate intensity (6 mT) static magnetic fields (MF). It was found that the following substances induced differentiation in U937 cells to a progressively lower degree: 50 ng/mL 12-0-tetradecanoyl-13-phorbol acetate (TPA), low concentration of glutamine (0,05 mM/L), 10% dimethyl sulfoxide (DMSO) and 100 mM/L Zn++. Differentiated U937 cells shift from a round shape to a macrophage-like morphology, from suspension to adhesion growth and acquire phagocytotic activity, the cytoskeleton adapting accordingly. Exposure to static MF at 6 mT of intensity decreases the degree of differentiation for all differentiating molecules with a consequent fall in cell adhesion and increased polarization of pseudopodia and cytoplasmic protrusions. Differentiation alone, or in combination with exposure to static MFs, affects the distribution and quantity of cell surface sugar residues, the surface expression of markers of macrophage differentiation, and phagocytotic capability. Our results indicate that moderate-intensity static MFs exert a considerable effect on the process of macrophage differentiation of pro-monocytic U937 cells and suggest the need for further studies to investigate the in vivo possible harmful consequences of this.

Inhibitory effects of a gradient static magnetic field on normal angiogenesis

Angiogenesis, the formation of new blood vessels, is critical in many normal and pathological processes such as development, reproduction, tumor growth, and metastasis. Recently, exposure to moderate-intensity static magnetic fields (1 mT to 1 T) has attracted much attention for its potential therapeutic value as a noninvasive intervening method. Nevertheless, the effects of moderate-intensity and spatial gradient static magnetic fields (GSMF) on angiogenesis have not received enough attention. In this study, the effects of GSMF (0.2-0.4 T, 2.09 T/m, 1-11 days) on angiogenesis were investigated both in vitro and in vivo. An MTT assay was used as an in vitro method to detect the proliferation ability of human umbilical veins endothelial cells (HUVECs). Two kinds of in vivo models, a chick chorioallantoic membrane (CAM) and a matrigel plug, were used to detect the effects of GSMF on angiogenesis. The results showed that the proliferation ability of HUVECs was significantly inhibited 24 h after the onset of exposure. With regard to the CAM model, vascular numbers in the CAM that was continuously exposed to the GSMF were all less than those in normal condition. In accordance with the gross appearance, the contents of hemoglobin in the models exposed to GSMF for 7-9 days were also less. In addition, similar to the CAM model, the results of vascular density and hemoglobin contents in the matrigel plug also demonstrated that the GSMF exposure for 7 or 11 days inhibited vascularization. These findings indicate that GSMF might inhibit or prevent new blood vessels formation and could be helpful for the treatment of some diseases relevant to pathological angiogenesis.

Effect of long term exposure to 0.5 T static magnetic fields on growth and size of GH3 cells

Brief exposure to moderate intensity static magnetic fields has been shown to produce a transient alteration in physiological function in a variety of biological systems, primarily those related to changes in intracellular Ca(2+). In the present study GH3 cells were cultured during continuous exposure to a 0.5 T field, for periods of up to 5 weeks. Following a 1-week exposure, cell growth declined by 22% and returned to control levels in 1 week. This was not statistically significant but, with a 4-week exposure, a statistically significant decline in growth of 51% was observed and return to control levels did not occur for 4 weeks. Cell diameter, on the other hand, significantly increased following 3 weeks of exposure and did not return to control levels for 3 weeks after termination of exposure. Ca(2+)-dependent changes in the dynamic reorganization of the actin cytoskeleton are suggested as the probable explanation for these observations.

The Influence of a gradient static magnetic field on an unstirred Belousov–Zhabotinsky reaction

It is believed that static magnetic fields (SMF) cannot affect the pattern formation of the Belousov-Zhabotinsky (BZ) reaction, which has been frequently studied as a simplified experimental model of a nonequilibrium open system, because SMF produces no induced current and the magnetic force of SMF far below 1 T is too low to expect the effects on electrons in the BZ reaction. In the present study, we examined whether the velocity of chemical waves in the unstirred BZ reaction can be affected by a moderate-intensity SMF exposure depending on the spatial magnetic gradient. The SMF was generated by a parallel pair of attracting rectangular NdFeB magnets positioned opposite each other. The respective maximum values of magnetic flux density (B(max)), magnetic flux gradient (G(max)), and the magnetic force product of the magnetic flux density its gradient (a magnetic force parameter) were 206 mT, 37 mT/mm, and 3,000 mT(2)/mm. The ferroin-catalyzed BZ medium was exposed to the SMF for up to 16 min at 25 degrees C. The experiments demonstrated that the wave velocity was significantly accelerated primarily by the magnetic gradient. The propagation of the fastest wave front indicated a sigmoid increase along the peak magnetic gradient line, but not along the peak magnetic force product line. The underlying mechanisms of the SMF effects on the anomalous wave propagation could be attributed primarily to the increased concentration gradient of the paramagnetic iron ion complexes at the chemical wave fronts induced by the magnetic gradient.

Effects of 12 mT static magnetic field on sympathetic agonist‐induced hypertension in wistar rats

We investigated the combined effects of a moderate-intensity static magnetic field (SMF) and two different sympathetic agonists, an alpha(1)-adrenoceptor agonist, phenylephrine and a beta(1)-adrenoceptor agonist, dobutamine, which induced hypertension and different hemodynamics in Wistar rats. Five-week-old male rats were continuously exposed to the SMF intensity of 12 mT (B(max)) with the peak spatial gradient of 3 mT/mm for 10 weeks. A loop-shaped flexible rubber magnet was adjusted to fit snugly around the neck region of a rat (diameter-adjustable to an animal size). Sham exposure was performed using a dummy magnet. Six experimental groups of six animals each were examined: (1) sham exposure with intraperitoneal (ip) saline injection (control); (2) SMF exposure with ip saline injection (SMF); (3) sham exposure with ip phenylephrine (1.0 microg/g) injection (PE); (4) SMF exposure with ip phenylephrine injection (SMF + PE); (5) sham exposure with ip dobutamine (4.0 microg/g) injection (DOB); (6) SMF exposure with ip dobutamine injection (SMF + DOB). Fifteen minutes after the injection of each agent, the first set of parameters, arterial blood pressure (BP) and heart rate (HR), the second set of parameters, skin blood flow (SBF) and skin blood velocity (SBV), or the third set of parameters, the number of rearing (exploratory behavior) responses and body weight was monitored. Each agent was administered three times a week for 10 weeks, and each set of parameters was monitored on different days, once a week. The dose of phenylephrine significantly increased BP and decreased HR, SBF, SBV, and the number of rearing responses in the PE group compared with those in the respective age-matched control group. The dose of dobutamine significantly increased BP and HR, increased SBF, SBV, and the number of rearing responses in the DOB group compared with those in the control group. Continuous neck exposure to the SMF alone for up to 10 weeks induced no significant changes in any of the measured cardiovascular and behavioral parameters. The SMF exposure for at least 2 weeks (1) significantly depressed phenylephrine effects on BP, SBF, SBV, and rearing activity (SMF + PE group vs. PE group); (2) significantly depressed dobutamine effects on BP, SBF, and SBV, and suppressed dobutamine-induced increase in the rearing activity (SMF + DOB group vs. DOB group). These results suggest that continuous neck exposure to 12 mT SMF for at least 2 weeks may depress or suppress sympathetic agonists-induced hypertension, hemodynamics, and behavioral changes by modulating sympathetic nerve activity.

Effects of static magnetic fields on the voltage-gated potassium channel currents in trigeminal root ganglion neurons

To evaluated the effects of moderate-intensity static magnetic fields (SMF) on two types of voltage-gated potassium channel (VGPC) currents: I K,A and I K,V, whole-cell patch-clamp experiments were conducted on acute dissociated rat trigeminal root ganglion (TRG) neurons. The results demonstrated that 125 mT SMF could influence the inactivation kinetics of these two VGPC currents by altering the inactivation rate and velocity. No significant change was observed in the activation properties. These findings supported the hypothesis that biological membrane would be deformed in moderate-intensity SMF and the physiological characteristics of ion channels on the membrane would be influenced. The mechanism underlying the different effects of SMF on the I K,A and I K,V inactivation was also discussed.