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Static magnetic field influence on rat brain function detected by heart rate monitoring.
Veliks V, Ceihnere E, Svikis I, Aivars J.
Faculty of Biology, University of Latvia, Riga, Latvia.
The aim of the present study was to identify the effects of a static
magnetic field (SMF) on rat brain structures that control autonomic
functions, specifically heart rate and heart rhythmicity. The
experiments were carried out on 44 male Wistar rats under
ketamine-xylazine anesthesia. SMF was induced using samarium-cobalt
fused magnets (20 x 20 x 10 mm in size) placed bitemporally. Magnetic
induction intensity was 100 mT on the surface of the head. Duration of
magnetic field application was 15 min. An electrocardiogram was recorded
from limb lead II, and both heart rate (average duration of cardiac
cycles) and heart rhythmicity were analyzed before and after SMF
application. SMF evoked changes in both heart rate and rhythm in 80% of
the animals; the predominant effects were bradycardia and disappearance
of respiratory sinus arrhythmia. However, the effectiveness of SMF in
large measure depends on both functional peculiarities and functional
activities of brain autonomic centers. Bioelectromagnetics 25:211-215,
2004. Copyright 2004 Wiley-Liss, Inc.
Bioelectromagnetics. 2004 Apr;25(3):211-5.
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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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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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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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Verapamil protective effect on natural and artificial magnetic field cardiovascular impact.
Gmitrov J, Ohkubo C.
Department of Physiological Hygiene, The National Institute of Public Health, Tokyo, Japan.
Previously we found an opposite effect of artificial static magnetic
field (SMF) and natural geomagnetic field (GMF) on arterial
baroreceptors. A 0.35 T SMF increased baroreflex sensitivity (BRS),
whereas GMF disturbance decreased BRS. Here, we investigated
interrelated impacts on arterial baroreceptors of 0.35 T SMF, generated
by Nd(2)-Fe(14)-B alloy magnets, GMF, and verapamil, a Ca(2+) channel
blocking agent. We measured BRS in rabbits before and after local SMF
exposure of sinocarotid baroreceptors or after simultaneous SMF and
verapamil application, in conjunction with geomagnetic disturbance
during actual experimental run (determined by K-index) and geomagnetic
disturbance over the preceding 24 h of each experiment (A(k)-index). BRS
was estimated from peak responses of mean arterial pressure (MAP) and
heart rate, expressed as percentages of the resting values preceding
each pair of pressure (phenylephrine) and depressor drug (nitroprusside)
injections. Prior to verapamil and/or SMF application we found a
significant positive correlation of K-index with MAP (t = 2.39, P =.021,
n = 44), but negative with BRS (t = -4.60, P =.0003, n = 44), and found
a negative correlation of A(k)-index with BRS (t = -2.7, P = 0.01, n =
44). SMF induced an increase in BRS (0.79 +/- 0.1 vs. 1.15 +/- 0.1
bpm%/mmHg%, initial value vs. SMF exposure, P <.0002, n = 26).
Verapamil infusion blocked the SMF and GMF effect on BRS, indicating
Ca(2+) channels as a possible site of both fields' impact. SMF and GMF
probably affect baroreceptor sensory transduction, modulating
baroreceptor membranes' Ca(2+) channel permeability. Copyright 2002
Wiley-Liss, Inc.
Bioelectromagnetics. 2002 Oct;23(7):531-41.
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Artificial static and geomagnetic field interrelated impact on cardiovascular regulation.
Gmitrov J, Ohkubo C.
Department of Physiological Hygiene, National Institute of Public Health, Tokyo, Japan. gmitrovj@yahoo.com
Spreading evidence suggests that environmental and artificial
magnetic fields have a significant impact on cardiovascular system. The
modulation of cardiovascular regulatory mechanisms may play a key role
in observed effects. The objective was to study interrelated impacts of
artificial static magnetic field (SMF) and natural geomagnetic field
(GMF) on arterial baroreceptors. We studied baroreflex sensitivity (BRS)
in conscious rabbits before and after 40 min of sham (n = 20) or
application of Nd2-Fe14-B alloy magnets (n = 26) to the sinocarotid
baroreceptor region in conjunction with GMF disturbance during the
actual experiment, determined by K- and A(k)-indexes from a local
geomagnetic observatory. SMF at the position of baroreceptors was 0.35
T. BRS was estimated from peak responses of mean arterial pressure (MAP)
and heart rate expressed as percentages of the resting values preceding
each pair of pressure (phenylephrine) and depressor drug
(nitroprusside) injections. We observed a significant increase in BRS
for the nitroprusside depressor test (0.78 +/- 0.1 vs. 1.15 +/- 0.14
bpm/mmHg%, initial value vs. SMF exposure, P <.0002) and a tendency
for phenylephrine pressor test to increase in BRS. Prior to SMF
exposure, a significant positive correlation was found between actual K
index values and MAP (t = 2.33, P =.025, n = 46) and a negative
correlation of the K index with BRS (t = -3.6, P =.001, n = 46). After
SMF exposure we observed attenuation of the geomagnetic disturbance
induced a decrease in BRS. Clinical trials should be performed to
support these results, but there is a strong expectation that 0.35 T SMF
local exposure to sinocarotid baroreceptors will be effective in
cardiovascular conditions with arterial hypertension and decreased BRS,
due to a favorable SMF effect on the arterial baroreflex. Magnets to the
sinocarotid triangle along with modification of the pharmacotherapy for
hypertension should be especially effective on days with intense
geomagnetic disturbance, in moderating sympathetic activation and
baroreceptor dysfunction. Copyright 2002 Wiley-Liss, Inc.
Bioelectromagnetics. 2002 Jul;23(5):329-38.
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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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Effects of isolated and combined effects of a constant magnetic
field and antiorthostatic hypokinesia on central hemodynamics in rats.
Kazakova RT, Badakva AM.
The effect of a constant magnetic field on central circulation of
rats was investigated during their exposure to antiorthostatic
hypokinesia. Circulation parameters were measured by impedance
rheoplethysmography. It was found that 3-hour exposure to a 0.4 T
magnetic field did not produce a significant effect on central
circulation, whereas exposure to hypokinesia caused substantial changes
which included decreases of heart rate, stroke volume and cardiac
output. During a combined exposure to a constant magnetic field and
antiorthostatic hypokinesia, the magnetic field exerted a beneficial
effect on central circulation.
Kosm Biol Aviakosm Med. 1991 Sep-Oct;25(5):48-9.
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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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