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Magnetic Therapy Research: Effect on Blood Flow

Acute exposure to a moderate strength static magnetic field reduces edema formation in rats.

Morris CE, Skalak TC. Department of Biomedical Engineering, University of Virginia Health Sciences Center, Health System, Charlottesville, VA 22908, USA.

News article on this study available.

External application of static magnetic fields (SMF), used specifically for the treatment of inflammatory conditions such as soft tissue injuries, has recently become popular as a complementary and/or alternative therapy with minimal investigation into efficacy or mechanism. Localized inflammation was induced via injection of inflammatory agents lambda-carrageenan (CA) or histamine into rat hindpaws, alone or in conjunction with pharmacological agents, resulting in a spatially and temporally defined inflammatory reaction. Application of a 10- or 70-mT, but not a 400-mT, SMF for 15 or 30 min immediately following histamine-induced edema resulted in a significant, 20-50% reduction in edema formation. In addition, a 2-h, 70-mT field application to CA-induced edema also resulted in significant (33-37%) edema reduction. Field application before injection or at the time of maximal edema did not influence edema formation or resolution, respectively. Together, these results suggest the existence of a therapeutic threshold of SMF strength (below 400 mT) and a temporal dependence of efficacy. Administration of pharmacological agents directed at nitric oxide signaling and L-type Ca(2+) channel dynamics in conjunction with SMF treatment and histamine-induced edema revealed that the potential mechanism of SMF action may be via modulation of vascular tone through effects on L-type Ca(2+) channels in vascular smooth muscle cells.

Morris CE, Skalak TC (January 2008). "Acute exposure to a moderate strength static magnetic field reduces edema formation in rats." American Journal of Physiolology: Heart & Circulatory Physiology 294(1):h20-7. PMID: 17982018

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Static magnetic fields affect capillary flow of red blood cells in striated skin muscle.

Brix G, Strieth S, Strelczyk D, Dellian M, Griebel J, Eichhorn ME, Andrā W, Bellemann ME. Federal Office for Radiation Protection, Department of Medical Radiation Hygiene and Dosimetry, Neuherberg, Germany.

Blood flowing in microvessels is one possible site of action of static magnetic fields (SMFs).

We evaluated SMF effects on capillary flow of red blood cells (RBCs) in unanesthetized hamsters, using a skinfold chamber technique for intravital fluorescence microscopy. By this approach, capillary RBC velocities (v(RBC)), capillary diameters (D), arteriolar diameters (D(art)), and functional vessel densities (FVD) were measured in striated skin muscle at different magnetic flux densities.

Exposure above a threshold level of about 500 mT resulted in a significant (P < 0.001) reduction of v(RBC) in capillaries as compared to the baseline value. At the maximum field strength of 587 mT, v(RBC) was reduced by more than 40%. Flow reduction was reversible when the field strength was decreased below the threshold level. In contrast, mean values determined at different exposure levels for the parameters D, D(art), and FVD did not vary by more than 5%.

Blood flow through capillary networks is affected by strong SMFs directed perpendicular to the vessels. Since the influence of SMFs on blood flow in microvessels directed parallel to the field as well as on collateral blood supply could not be studied, our findings should be carefully interpreted with respect to the setting of safety guidelines.

Brix G, Strieth S, Strelczyk D, Dellian M, Griebel J, Eichhorn ME, Andrā W, Bellemann ME (January 2008). "Static magnetic fields affect capillary flow of red blood cells in striated skin muscle."Microcirculation. 15(1):15-26. PMID: 17952798

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Chronic static magnetic field exposure alters microvessel enlargement resulting from surgical intervention.

Morris CE, Skalak TC. Dept. of Biomedical Engineering, Univ. of Virginia Health Sciences Center, Charlottesville, VA 22908, USA.

Magnetic field therapy has recently become a widely used complementary/alternative medicine for the treatment of vascular, as well as other musculoskeletal pathologies, including soft tissue injuries. Recent studies in our laboratory and others have suggested that acute static magnetic field (SMF) exposure can have a modulatory influence on the microvasculature, acting to normalize vascular function; however, the effect of chronic SMF exposure has not been investigated. This study aimed to measure, for the first time, the adaptive microvascular response to a chronic 7-day continuous magnetic field exposure. Murine dorsal skinfold chambers were applied on day 0, and neodymium static magnets (or size and weight-matched shams) were affixed to the chambers at day 0, where they remained until day 7. Separate analysis of arteriolar and venular diameters revealed that chronic SMF application significantly abrogated the luminal diameter expansion observed in sham-treated networks. Magnet-treated venular diameters were significantly reduced at day 4 and day 7 (34.3 and 54.4%, respectively) compared with sham-treated vessels. Arteriolar diameters were also significantly reduced by magnet treatment at day 7 (50%), but not significantly at day 4 (31.6%), although the same trend was evident. Venular functional length density was also significantly reduced (60%) by chronic field application. These results suggest that chronic SMF exposure can alter the adaptive microvascular remodeling response to mechanical injury, thus supporting the further study of chronic application of SMFs for the treatment of vascular pathologies involving the dysregulation of microvascular structure.

Morris CE, Skalak TC (August 2007). "Chronic static magnetic field exposure alters microvessel enlargement resulting from surgical intervention." Journal of Applied Physiology 103(2): 629-36. PMID: 17478604

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Static magnetic fields alter arteriolar tone in vivo.

Morris CE, Skalak TC. Department of Biomedical Engineering, University of Virginia, Charlottesville, VA 22908, USA.

This study was designed to directly quantify the effect of localized static magnetic field (SMF) exposure on the diameter of microvessels in adult rat skeletal muscle in vivo. Microvascular networks in the exteriorized rat spinotrapezius microvasculature were exposed to a localized, uniform 70 mT SMF for 15 min. Arteriolar vessel diameters were measured; and the extent of vessel contraction, microvascular tone, was calculated before exposure, immediately after exposure, and 15 and 30 min after removal of the field. A calculated value of high tone corresponds to vessels that are vasoconstricted and a calculated value of low tone refers to vessels that are vasodilated. Vessels with initial tone <15% showed an increasing trend in tone and, conversely, vessels with initial tone >15% showed a significant (P < 0.05) decrease in tone 15 and 30 min following application, respectively. Further classification of the data with regards to the initial vessel diameter demonstrated that vessels with initial diameters <30 microm and initial tone <15%, smaller diameter vessels that are initially vasodilated, showed significant (P < 0.05) increase in tone immediately, 15 and 30 min following SMF exposure. Additionally, <30 microm vessels with >15% initial tone, smaller diameter vessels that are initially vasoconstricted, demonstrated a significant (P < 0.05) decrease in tone 30 min after SMF exposure. Vessels with initial diameters >30 microm had no significant response to the SMF. These results imply that SMF exposure influences arteriolar diameters, and therefore microvascular tone, in a restorative fashion acting to normalize the tone to the median tone value of 15% following exposure. Because this response occurs primarily in the resistance arterioles, which significantly influence tissue perfusion, SMF application could be efficacious for the treatment of both ischemic and edematous tissue disorders involving compromised microvascular function.

Morris CE, Skalak TC (January 2005). "Static magnetic fields alter arteriolar tone in vivo." Bioelectromagnetics 26(1): 1-9. PMID: 15605401

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Effects of neck exposure to 5.5 mT static magnetic field on pharmacologically modulated blood pressure in conscious rabbits.

Okano H, Ohkubo C. Department of Environmental Health, National Institute of Public Health, Saitama, Japan. okano@iic.kyoto-u.ac.jp

Static magnetic fields (SMF) in the millitesla (mT) range have been reported to modulate microcirculatory hemodynamics and/or blood pressure (BP) under pharmacologically modified state in mammals. This study was designed to investigate the acute effects of local application of a SMF to neck or pelvic region under pharmacologically modulated BP; norepinephrine (NE)-induced hypertension as well as an L-type voltage-gated Ca(2+) channel blocker, nicardipine (NIC)-induced hypotension in conscious rabbits. Magnetic flux densities were up to 5.5 mT and the spatial magnetic gradient peaked in neck (carotid sinus baroreceptor) region at the level of approximately 0.06 mT/mm. The duration of exposure was 30 min (including 10 min of pretreatment) and the effects on BP were investigated up to 100 min postexposure. Baroreflex sensitivity (BRS) was estimated from invasive recordings of systolic BP and pulse interval. Neck exposure to 5.5 mT significantly attenuated the pharmacologically induced vasoconstriction or vasodilation, and subsequently suppressed the increase or decrease in BP compared with sham exposure. In contrast, pelvic exposure to 5.5 mT did not significantly antagonized NE-elevated BP or NIC-reduced BP. The neck exposure to 5.5 mT has a biphasic and restorative effect on vascular tone and BP acting to normalize the tone and BP. The neck exposure to 5.5 mT caused a significant increase in BRS in NE-elevated BP compared with sham exposure. The buffering effects of the SMF on increased hemodynamic variability under NE-induced high vascular tone and NIC-induced low vascular tone might be, in part, dependent on baroreflex pathways, which could modulate NE-mediated response in conjunction with Ca(2+) dynamics. (c) 2005 Wiley-Liss, Inc.

PMID: 16108042 [PubMed - in process]

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Effects of a static magnetic field of either polarity on skin microcirculation.

Mayrovitz HN, Groseclose EE. College of Medical Sciences, Nova Southeastern University, 3200 S. University Drive, Ft. Lauderdale, FL 33328, USA. mayrovit@nova.edu

Our specific aim was to investigate whether a local static magnetic field of a permanent magnet, of either pole, affects resting skin blood perfusion. This was done by measuring skin blood perfusion (SBF) by laser-Doppler in dorsum skin of 2nd and 4th fingers of the nondominant hands of 12 volunteers. Both fingers were first exposed to sham magnets, and then the 2nd finger was exposed alternately to north and south poles of a neodymium magnet that produced a field of 4024 G at the palmar part of the finger and a field of 879 +/- 52 G at the site of finger dorsum SBF measurement. Each of the three exposure intervals was 15 min. SBF values were analyzed by first computing the average SBF during the last 5 min of each of the three 15-min exposure intervals. These SBF averages were initially tested for magnet or magnet-pole effects by analysis of variance for repeated measures with finger as a factor, using SBF values for each finger as the test variable. Results of this analysis revealed a large variability in finger SBF among subjects and no significant difference in SBF between exposure conditions (P = 0.705) or any significant interaction between SBF and finger (P = 0.396). However, when intersubject variability was reduced by using the flow difference between treated and nontreated fingers in each exposure interval as the test variable, a statistically significant effect (P = 0.016) attributable to magnet exposure was uncovered. This effect was a reduction in resting SBF in the magnet-exposed fingers that was similar for north and south pole magnet exposure. The present findings are the first to demonstrate a direct effect of locally applied magnets on human skin blood perfusion.

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Recovery of Small-Sized Blood Vessels in Ischemic Bone Under Static Magnetic Field

Shenzhi Xu1,2, Naohide Tomita1, Ken Ikeuchi3 and Yoshito Ikada4 1International Innovation Center, Kyoto University Kyoto, Japan 2Department of Sciences, Pip Tokyo Co. Ltd, Tokyo, Japan 3Institute for Frontier Medical Sciences, Kyoto University Kyoto, Japan 4Faculty of Medical Engineering, Suzuka University of Medical Science Mie, Japan

Effects of static magnetic field (SMF) on the vascularization in bone were evaluated using an ischemic bone model, where rat femoral artery was ligated. Magnetized and unmagnetized samarium–cobalt rods were implanted transcortically into the middle diaphysis of the ischemic femurs. Collateral circulation was evaluated by injection of microspheres into the abdominal aorta at the third week after ligation. It was found that the bone implanted with a magnetized rod showed a larger amount of trapped microspheres than that with an unmagnetized rod at the proximal and the distal region (P < 0.05 proximal region). There were no significant differences at the middle and the distal region. This tendency was similar to that of the bone mineral density in the SMF-exposed ischemic bone.

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

Okano H, Ohkubo C. Department of Environmental Health, National Institute of Public Health, Saitama, Japan.

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.

PMID: 17330852 [PubMed - as supplied by publisher]

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Decreased plasma levels of nitric oxide metabolites, angiotensin II, and aldosterone in spontaneously hypertensive rats exposed to 5 mT static magnetic field.

Okano H, Masuda H, Ohkubo C. Department of Environmental Health, National Institute of Public Health, Tokyo 108-8638, Japan. okano@niph.go.jp

Previously, we found that whole body exposure to static magnetic fields (SMF) at 10 mT (B(max)) and 25 mT (B(max)) for 2-9 weeks suppressed and delayed blood pressure (BP) elevation in young, stroke resistant, spontaneously hypertensive rats (SHR). In this study, we investigated the interrelated antipressor effects of lower field strengths and nitric oxide (NO) metabolites (NO(x) = NO(2)(-) + NO(3)(-)) in SHR. Seven-week-old male rats were exposed to two different ranges of SMF intensity, 0.3-1.0 mT or 1.5-5.0 mT, for 12 weeks. Three experimental groups of 20 animals each were examined: (1) no exposure with intraperitoneal (ip) saline injection (sham-exposed control); (2) 1 mT SMF exposure with ip saline injection (1 mT); (3) 5 mT SMF exposure with ip saline injection (5 mT). Arterial BP, heart rate (HR), skin blood flow (SBF), plasma NO metabolites (NO(x)), and plasma catecholamine levels were monitored. SMF at 5 mT, but not 1 mT, significantly suppressed and retarded the early stage development of hypertension for several weeks, compared with the age matched, unexposed (sham exposed) control. Exposure to 5 mT resulted in reduced plasma NO(x) concentrations together with lower levels of angiotensin II and aldosterone in SHR. These results suggest that SMF may suppress and delay BP elevation via the NO pathways and hormonal regulatory systems.

PMID: 15768432 [PubMed - indexed for MEDLINE]

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Effects of static magnetic fields on plasma levels of angiotensin II and aldosterone associated with arterial blood pressure in genetically hypertensive rats.

Okano H, Ohkubo C.

Department of Environmental Health, National Institute of Public Health, Tokyo, Japan. okano@niph.go.jp

Effects of static magnetic fields (SMFs) on development of hypertension were investigated using young male, stroke resistant, spontaneously hypertensive rats (SHRs) beginning at 7 weeks of age. SHRs were randomly assigned to two different exposure groups or an unexposed group. The SHRs in the exposure groups were constantly exposed to two different types of external SMFs of 3.0-10.0 mT or 8.0-25.0 mT for 12 weeks. The SMFs were generated from permanent magnetic plates attached to the rat cage. The blood pressure (BP) of each rat was determined at weekly intervals using indirect tail-cuff method. The SMFs suppressed and retarded the development of hypertension in both exposed groups to a statistically significant extent for several weeks, as compared with an unexposed group. The antipressor effects were related to the extent of reduction in plasma levels of angiotensin II and aldosterone in the SHRs. These results suggest that the SMFs of mT intensities with spatial gradients could be attributable to suppression of early BP elevation via hormonal regulatory system. Copyright 2003 Wiley-Liss, Inc.

Bioelectromagnetics. 2003 Sep;24(6):403-12.

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Use of permanent magnetic field in reconstructive surgery of the main arteries (experimental study).

Lud GV, Demeckiy AM.

Department of Surgery, Vitebsk Medical Institute, USSR.

To achieve better results in reconstructive surgery on the main arteries using venous graft, the authors used a permanent magnetic field from different sources: elastic magnets with external effect and absorbable magnets implanted into the surgical wound. This physical source was found to possess the following effects: stimulation of the central and peripheral blood flow, hypercoagulation prevention, reduction on edema and inflammation. The restored specific properties of these magnetic sources should be taken into account in the selection and use during the postoperative period.

PMID: 1694619 [PubMed - indexed for MEDLINE]

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Anti-pressor effects of whole body exposure to static magnetic field on pharmacologically induced hypertension in conscious rabbits.

Okano H, Ohkubo C.

Department of Environmental Health, National Institute of Public Health, Tokyo, Japan. okano@niph.go.jp

Acute effects of whole body exposure to static magnetic field (SMF) on pharmacologically induced hypertension in a conscious rabbit were evaluated. Hypertensive and vasoconstrictive actions were induced by norepinephrine (NE) or a nonselective nitric oxide synthase (NOS) inhibitor, N(omega)-nitro-l-arginine methyl ester (l-NAME). The hemodynamics in a central artery of the ear lobe was measured continuously and analyzed by penetrating microphotoelectric plethysmography (MPPG). Concurrently, blood pressure (BP) changes in a central artery, contralateral to that of the MPPG measured ear lobe, were monitored. Magnetic flux densities were 5.5 mT (Bmax), the magnetic gradient peaked in the throat at the level of approximately 0.09 mT/mm, and the duration of exposure was 30 min. The results demonstrated that under normal physiological conditions without treatment of pharmacological agents, there were no statistically significant differences in the hemodynamics and BP changes between the sham and the SMF exposure alone. Under pharmacologically induced hypertensive conditions, the whole body exposure to nonuniform SMF with peak magnetic gradient in the carotid sinus baroreceptor significantly attenuated the vasoconstriction and suppressed the elevation of BPs. These findings suggest that antipressor effects of the SMF on the hemodynamics under NE or l-NAME induced high vascular tone might be, in part, dependent on modulation of NE mediated response in conjunction with alteration in NOS activity, thereby modulating BPs. Copyright 2003 Wiley-Liss, Inc.

Bioelectromagnetics. 2003 Feb;24(2):139-47.

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Effect of 0.25 T static magnetic field on microcirculation in rabbits.

Gmitrov J, Ohkubo C, Okano H.

Department of Physiological Hygiene, The National Institute of Public Health, Tokyo, Japan. gmitrovj@yahoo.com

We showed previously in rabbits that 0.2 and 0.35 T static magnetic field (SMF) modulated systemic hemodynamics by arterial baroreceptors. We now have measured the effect of 0.25 T SMF on microcirculation within cutaneous tissue of the rabbit ear lobe by the rabbit ear chamber (REC) method. Forty experimental runs (20 controls and 20 SMF) were carried out in eight different rabbits with an equal number of control and SMF experiments on each individual. Rabbits were sedated by pentobarbital sodium (5 mg/kg/h, i.v.) during the entire 80 min experiment. SMF was generated by four neodium-iron-boron alloy (Nd2-Fe14-B) magnets (15 x 25 x 30 mm, Neomax, PIP - Tokyo Co., Ltd., Tokyo, Japan), positioned around the REC on the observing stage of an optical microscope. The direct intravital microscopic observation of the rabbit's ear microvascular net, along with simultaneous blood flow measurement by microphotoelectric plethysmography (MPPG), were performed PRE (20 min, baseline), DURING (40 min), and POST (20 min) magnetic field exposure. The control experiments were performed under the same conditions and according to the same time course, but without magnetic field. Data were analyzed comparing MPPG values and percent change from baseline in the same series, and between corresponding sections of control and SMF runs. In contrast to control series (100+/-0.0%-90.0+/-5.4%-87.7+/-7.1%, PRE-EXPOSURE-POST), after magnetic field exposure we observed increased blood flow (100+/-0.0%-117.8+/-9.6%*-113.8+/-14.0%, *P<0.05) which gradually decreased after exposure cessation. We propose that long exposure of a high level nonuniform SMF probably modifies microcirculatory homeostasis through modulation of the local release of endothelial neurohumoral and paracrine factors that act directly on the smooth muscle of the vascular wall, presumably by affecting ion channels or second messenger systems.

Bioelectromagnetics. 2002 Apr;23(3):224-9.

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Magnetic behavior of human erythrocytes at different hemoglobin states.

Sakhnini L, Khuzaie R.

Physics Department, College of Science, University of Bahrain, State of Bahrain. l_sakhnini@yahoo.com

The effect of a static magnetic field on human erythrocytes at different hemoglobin states (normal, oxidized and reduced hemoglobin) was investigated. Three different blood samples, normal, iron deficiency anemic and beta thalassemia minor, were studied. Measurements of the magnetization curves of the erythrocytes for all blood samples in all states showed diamagnetic behavior; however, oxidation was found to enhance this behavior. These measurements have also shown that the normal and iron deficiency samples in the reduced states exhibit a less diamagnetic response in comparison with the normal state. This result indicates that the reduction process gave rise to a paramagnetic component of the magnetization. Analysis of the measured paramagnetic behavior, using a Brillouin function, gave an effective magnetic moment of 8 muB per reduced hemoglobin molecule for both normal and anemic samples. This result shows that both anemic and normal blood have similar magnetic behavior and the only difference is the number of hemoglobin molecules per erythrocyte. For the beta thalassemia minor blood sample, magnetic measurements showed that both the normal and reduced states have almost the same diamagnetic behavior. However, this diamagnetic response is less than that for the normal state of the iron deficiency anemic sample. This result may indicate a low oxygen intake for the blood in the normal state for the beta thalassemia minor blood. All magnetic measurements were made using a vibrating sample magnetometer using field steps of 0.001 T from 1 T to -1 T.

Eur Biophys J. 2001 Oct;30(6):467-70.

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Modulatory effects of static magnetic fields on blood pressure in rabbits.

Okano H, Ohkubo C.

Department of Physiological Hygiene, National Institute of Public Health, Tokyo, Japan. okano@iph.go.jp

Acute effects of locally applied static magnetic fields (SMF) on pharmacologically altered blood pressure (BP) in a central artery of the ear lobe of a conscious rabbit were evaluated. Hypotensive and vasodilator actions were induced by a Ca(2+) channel blocker, nicardipine (NIC). Hypertensive and vasoconstrictive actions were induced by a nitric oxide synthase (NOS) inhibitor, N(omega)-nitro-L-arginine methyl ester (L-NAME). The hemodynamic changes in the artery exposed to SMF were measured continuously and analyzed by penetrating microphotoelectric plethysmography (MPPG). Concurrently, BP changes in a central artery contralateral to that of the exposed ear lobe were monitored. SMF intensity was 1 mT and the duration of exposure was 30 min. A total of 180 experimental trials were carried out in 34 healthy adult male rabbits weighing 2.6-3.8 kg. Six experimental procedures were chosen at random: (1) sham exposure without pharmacological treatment; (2) SMF exposure alone; (3) decreased BP induced by a single intravenous (iv) bolus injection of NIC (100 microM/kg) without SMF exposure; (4) decreased BP induced by injection of NIC with SMF exposure; (5) increased BP induced by a constant iv infusion of L-NAME (10 mM/kg/h) without SMF exposure; (6) increased BP induced by infusion of L-NAME with SMF exposure. The results demonstrated that SMF significantly reduced the vasodilatation with enhanced vasomotion and antagonized the reduction of BP via NIC-blocked Ca(2+) channels in vascular smooth muscle cells. In addition, SMF significantly attenuated the vasoconstriction and suppressed the elevation of BP via NOS inhibition in vascular endothelial cells and/or central nervous system neurons. These results suggest that these modulatory effects of SMF on BP might, in part, involve a feedback control system for alteration in NOS activity in conjunction with modulation of Ca(2+) dynamics. Copyright 2001 Wiley-Liss, Inc.

Bioelectromagnetics. 2001 Sep;22(6):408-18.

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Acute effects of whole-body exposure to static magnetic fields and 50-Hz electromagnetic fields on muscle microcirculation in anesthetized mice.

Xu S, Okano H, Ohkubo C.

Department of Physiological Hygiene, National Institute of Public Health, Tokyo, Japan.

Acute microhemodynamic effects of static and alternating magnetic fields at a threshold level were investigated on modulating the muscle capillary mirocirculation in pentobarbital-anesthetized mice. The skin in a tibialis anterior was circularly removed with 1.5 mm diameter for intravital-microscopic recording of the capillary blood velocity in the tibialis anterior muscle. Fluorescein isothiocyanate (FITC)-labeled dextran (MW 150 kDa) was used for an in vivo fluorescent plasma marker of the muscle capillaries. Following a bolus injection of FITC-dextran solution into the caudal vein, the peak blood velocity in the muscle capillaries was measured prior to, during, and following exposure to static magnetic fields (SMF) or 50-Hz electromagnetic fields (EMF) using a fluorescence epi-illumination system. The whole body of experimental animals, placed on the observing stage of a fluorescence microscope, was exposed to SMF (0.3, 1 and 10 mT) or 50-Hz EMF (0.3 and 1 mT) for 10 min using a specially devised electromagnet. For sham exposure, the electromagnet was not energized. During exposure and post-exposure to SMF of 10 mT, the peak blood velocity significantly increased as compared to sham exposure. After the withdrawal of SMF and 50-Hz EMF of 1 mT, significant similar effects on the blood velocity were present or enhanced. These findings suggest that field intensity of 1 mT might be considered as a threshold level for enhancing muscle microcirculation under pentobarbital-induced hypnosis.

Bioelectrochemistry. 2001 Jan;53(1):127-35.

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Biphasic effects of static magnetic fields on cutaneous microcirculation in rabbits.

Okano H, Gmitrov J, Ohkubo C.

Department of Physiological Hygiene, National Institute of Public Health, Tokyo, Japan.

The biphasic effects of locally applied static magnetic fields (SMF) on the cutaneous microcirculation within a rabbit ear chamber (REC) were evaluated under conscious conditions. The microcirculatory vasomotion within a REC was measured continuously and analyzed multilaterally by microphotoelectric plethysmography, a real-time image analyzer and an image shearing monitor. SMF intensities at the REC were controlled at 1 mT and the duration of exposure was 10 min. Seventy-eight experimental trials were carried out on 22 healthy adult rabbits weighing 2.6-3.5 kg. Five experimental groups were chosen at random: 1) no pharmacological treatment or SMF exposure, 2) increased vascular tone induced by noradrenaline infusion without SMF exposure, 3) increased vascular tone induced by noradrenaline infusion with SMF exposure, 4) decreased vascular tone induced by acetylcholine infusion without SMF exposure, 5) decreased vascular tone induced by acetylcholine infusion with SMF exposure. The results demonstrated that SMF significantly enhanced vasodilatation, with increased vasomotion under noradrenaline-induced high vascular tone as well as vasoconstriction with reduced vasomotion under acetylcholine-induced low vascular tone. This suggests, therefore, that SMF can modulate vascular tone due to biphasic modification of vasomotion in the cutaneous tissue.

Bioelectromagnetics. 1999;20(3):161-71.

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Subchronic effects of static magnetic fields on cutaneous microcirculation in rabbits.

Xu S, Okano H, Ohkubo C.

Department of Physiological Hygiene, National Institute of Public Health, Tokyo, Japan.

The subchronic effects of locally applied of static magnetic fields (SMF) on the cutaneous microcirculation within the rabbit ear chamber (REC) were evaluated under conscious conditions. The microcirculatory vasomotion within a REC was measured continuously and analyzed multilaterally by microphotoelectric plethysmography and an image shearing monitor. A SMF, a 180 mT (milli Tesla) cylindlical samarium-cobalt permanent magnet was attached on REC for 24 hours to 4 weeks Exposure to SMF for 1-3 weeks significantly induced long-lasting vasodilation with enhanced vasomotion as compared to control group. Thereafter the active vasomotion of SMF group was depressed and/or returned to initial values and there was no difference between SMF and control groups. The results suggest that the subchronic exposure of SMF can bidirectionally modulate microcirculatory vasomotion in cutaneous tissue.

In Vivo. 1998 Jul-Aug;12(4):383-9.

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Acute effects of static magnetic fields on cutaneous microcirculation in rabbits.

Ohkubo C, Xu S.

Department of Physiol, Hygiene, National Institute of Public Health, Tokyo, Japan.

The acute microcirculatory effects of locally applied of static magnetic (SMF) to the cutaneous tissue within a rabbit ear chamber (REC) were evaluated during consciousness. Rabbits with REC were subjected to microphotoelectric plethysmography. Power levels of SMF upon the REC were controlled at 1, 5, 10 mT(milli Tesla), respectively. The duration of exposure was 10 minutes. The exposure of SMF induced variation of vasomotion with a latency of about 10 seconds in a non-dose dependent manner. SMF had a biphasic effect upon the microcirculatory system; when the vascular tone was low, the SMF enhanced vasomotion, and when it was high, the SMF suppressed vasomotion. The results suggest that the SMF can modulate vascular tone due to vasomotion which may involve in clinical efficacy for refraining from neck and shoulder stiffness.

In Vivo. 1997 May-Jun;11(3):221-5.

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Magnetic field effect on blood pressure regulation.

Gmitrov J, Ivanco I, Gmitrova A.

Department of Physiology, Medical Faculty of Safarik University, Kosice.

The present results are a continuation of our experiments demonstrating the fact that the local action of a permanent magnetic field (PMF) with an intensity of 0.2 T on the rabbits carotid sinus area under pentobarbital anaesthesia has a hypotensive effect under normotonic conditions (Gmitrova et al. 1987). The aim of this paper was to investigate the PMF influence on the carotid sinus region during artificial hypotension in rabbits. The experiments were carried out in rabbits under pentobarbital anaesthesia under hypotonic conditions caused by electrostimulation of the right depressor nerve. Blood pressure, heart rate and respiration rate changes were monitored before the application of PMF (0.2 T intensity) on the sinocarotid region, during the "on" effect of PMF, under the PMF action, during the PMF "off" effect and after PMF application. PMF significantly decreased the depressor effect of depressor nerve electrostimulation in contrast to the condition of normotonia, where PMF had a hypotensive effect.

Physiol Bohemoslov. 1990;39(4):327-34.

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