Effect of a static magnetic field on blood flow to the metacarpus in horses

Steyn, Phillip F.; Ramey, David W.; Kirschvink, Joseph L.; Uhrig, John

doi:10.2460/javma.2000.217.874

Cited by 26 publications

(27 citation statements)

References 20 publications

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“…However, our results are supported by studies in humans that report no changes during exposure to magnets with strengths less than 1 T in both muscle and skin blood flow at rest (20,23) and during deep inspiration (22). Likewise, wrapping the metacarpus region of the horse with 0.027-T magnets did not alter blood flow in that region (32). The finding of the present study supports the conclusion that exposure to static magnetic fields, at the strength commonly used in nominally therapeutic devices, do not elicit changes in local blood flow, blood pressure, or heart rate in humans at rest or during physiological stress.…”

Section: Discussionsupporting

confidence: 86%

Influence of static magnetic fields on pain perception and sympathetic nerve activity in humans

Kuipers

Sauder²,

Ray³

2007

Journal of Applied Physiology

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Static and pulsed magnetic fields have been reported to have a variety of physiological effects. However, the effect of static magnetic fields on pain perception and sympathetic function is equivocal. To address this question, we measured pain perception during reproducible noxious stimuli during acute exposure to static magnets. Pain perception, muscle sympathetic nerve activity, mean arterial pressure, heart rate, and forearm blood velocity were measured during rest, isometric handgrip, postexercise muscle ischemia, and cold pressor test during magnet and placebo exposure in 15 subjects (25 +/- 1 yr; 8 men and 7 women) following 1 h of exposure. During magnet exposure, subjects were placed on a mattress with 95 evenly spaced 0.06-T magnets imbedded in it. During placebo exposure, subjects were placed on an identical mattress without magnets. The order of the two exposure conditions was randomized. At rest, no significant differences were noted in muscle sympathetic nerve activity (8 +/- 1 and 7 +/- 1 bursts/min for magnet and placebo, respectively), mean arterial pressure (91 +/- 3 and 93 +/- 3 mmHg), heart rate (63 +/- 2 and 62 +/- 2 beats/min), and forearm blood velocity (3.0 +/- 0.3 and 2.6 +/- 0.3 cm/s). Magnets did not alter pain perception during the three stimuli. During all interventions, no significant differences between exposure conditions were found in muscle sympathetic nerve activity and hemodynamic measurements. These results indicate that acute exposure to static magnetic fields does not alter pain perception, sympathetic function, and hemodynamics at rest or during noxious stimuli.

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Section: Discussionsupporting

confidence: 86%

Influence of static magnetic fields on pain perception and sympathetic nerve activity in humans

Kuipers

Sauder²,

Ray³

2007

Journal of Applied Physiology

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“…There is additional evidence that the applications of moderate, strong, and ultrastrong intensity SMF ranging 1 mT-8 T to healthy subjects and animals mask hemodynamic effects. These SMF intensities exhibited no significant effects on BP, SBF or locomotor activity in healthy humans or animals up to 8 T [Battocletti et al, 1981;Tenforde et al, 1983;Davis et al, 1984;Willis and Brooks, 1984;Barker and Cain, 1985;Mészáros, 1991;Stick et al, 1991;Kangarlu et al, 1999;Steyn et al, 2000;Mayrovitz et al, 2001Mayrovitz et al, , 2005Hinman, 2002;Martel et al, 2002;Tenforde, 2005]. These studies, including our own, provide evidence that normal cardiovascular system and locomotor activity are not easily affected by moderate-intensity SMF.…”

Section: Discussionsupporting

confidence: 52%

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

Okano

Ohkubo

2007

Bioelectromagnetics

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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.

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“…In particular, our series of studies (Ohkubo and Xu 1997;Xu et al 1998Xu et al , 2000Okano et al 1999Okano and Ohkubo 2001, 2003a, b, 2005a, b, 2007Gmitrov et al 2002;Gmitrov and Ohkubo 2002a, b) and other independent studies (Prato et al 1990;Steyn et al 2000;Mayrovitz et al 2001Martel et al 2002;Morris and Skalak 2005Kuipers et al 2007;Li et al 2007;Kim et al 2010), as shown in Table 1, have demonstrated that hemodynamics and/or BP were modulated by moderate intensity SMF in mT level fields in pharmacologically treated animals and genetically hypertensive animals, while there was no change in normal, conscious animals when the values of the BP were within normal range (reference values). Therefore, we concluded that significant bioresponses to therapeutic signals occur when the deviations of the endpoints are far from homeostasis.…”

Section: Discussionmentioning

confidence: 95%

Clinical aspects of static magnetic field effects on circulatory system

Ohkubo

Okano

2010

Environmentalist

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Increased knowledge of the magnetic field influence on hemodynamic function may have significant therapeutic potential and possible health effects. For example, magnetic field therapy using moderate intensity static magnetic fields (SMF) in the mT range (in particular, 1-600 mT) could be useful for circulatory diseases, including ischemic pain, inflammation, and hypertension, primarily due to the modulation of blood flow and/or blood pressure through the nervous system. We suggested that the mechanisms of SMF effects on the circulatory system in the mT range could be mediated by suppressing or enhancing the action of biochemical effectors, thereby inducing homeostatic effects biphasically. The potent mechanisms of SMF effects have often been linked to nitric oxide pathway, Ca 2? -dependent pathway, sympathetic nervous system (e.g., BRS and the action of sympathetic agonists or antagonists), and neurohumoral regulatory system (e.g., production and secretion of angiotensin II and aldosterone). Thus, this review mainly focuses on the experimental studies of SMF effects on the circulatory system in animals and may provide the physiological basis for future clinical investigations of SMF therapy.

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Effect of a static magnetic field on blood flow to the metacarpus in horses

Abstract: Results suggest that in horses, the static magnetic field associated with application of commercially available magnetic wraps for 48 hours does not increase blood flow to the portion of the metacarpus underneath the wrap.

Cited by 26 publications

References 20 publications

Influence of static magnetic fields on pain perception and sympathetic nerve activity in humans

Influence of static magnetic fields on pain perception and sympathetic nerve activity in humans

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

Clinical aspects of static magnetic field effects on circulatory system

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