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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