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Research: Magnetic Therapy & Cardiovascular Regulation

 

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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