135
Static, Low-Frequency, and Pulsed Magnetic Fields
heart rate trends over time appears to be associated with a combination of inactivity
(resulting in decreased body temperatures) and reduced physiological arousal. In contrast, Nishimura et al. (2011) suggested that repeated exposure to an ELF-EMF (6 and
8 Hz, 1 μT, 10 V/m, for at least two 10- to 15-minute sessions per week, over a period
of 4 weeks) has a blood pressure–lowering effect on humans with mild-to-moderate
hypertension.
Robertson et al. (2007) reviewed several mechanisms of protection, such as HSPs,
opioids, collateral blood flow, and NO induction, and the evidence supporting the use
of ELF-EMF as a means of providing protection in each of these mechanisms. Although
there are few studies demonstrating direct protection with ELF-EMF therapies, there
are many published reports indicating that ELF-EMF may be able to influence some of
the biochemical systems with protective applications.
McKay et al. (2010) investigated the acute effect of a PEMF (72 Hz, 225 μT, 6.7 mV/m,
for 30 and 60 minutes) on blood flow in the skeletal microvasculature of a male Sprague
Dawley rat model. Acetylcholine (0.1, 1.0, and 10.0 mM) was used to perturb normal
blood flow and to delineate the differential effects of PEMF, based on the degree of vessel
dilation. The authors found that there were no significant effects of PEMF on peak blood
flow, heart rate, and myogenic activity, but a small attenuation effect on anestheticinduced respiratory depression was noted.
3.3.1.6 Neuroendocrine, Visual, and Neurophysiological Systems
Neuroendocrine, visual, and neurophysiological systems also are considered to be
related to the aforementioned magnetic perception (3.3.1.1), analgesia (3.3.1.3), and circulatory system (3.3.1.5). Zhang et al. (2007) examined the effects of long-term exposures to a near-zero magnetic environment on the noradrenergic activities in the brain
stem of golden hamsters. Both the content of norepinephrine (NE) and the density of
NE-immunopositive neurons in tissue decreased significantly after the treatment, and
the effects were found to be progressive with time. These variations may contribute substantially to the behavioral and mood disorders reported in other studies that occur
when animals are shielded from the geomagnetic field.
Jeong, Choi, Choi, et al. (2005) investigated the effect of an ELF-EMF (60 Hz, 2.5 mT)
on convulsions in rats. The authors determined the onset and duration of convulsions
induced by exposure to bicuculline alone or by coexposure to ELF-EMF and bicuculline. Coexposure to ELF-EMF and bicuculline decreased GABA levels in the cortex,
hippocampus, and hypothalamus, whereas exposure to ELF-EMF alone reduced the
levels of GABA only in the hippocampus. These results suggest that ELF-EMF may
modulate bicuculline-induced convulsions due to GABA neurotransmissions in rat
brains.
Varró et al. (2009) examined the effects of ELF-EMF (50 Hz, 250–500 μT) on synaptic
efficacy in the central nervous system. Electrophysiological investigation was carried out
ex vivo in rat neocortical and hippocampal slices, and basic synaptic functions, shortterm plasticity (STP) and long-term plasticity (LTP), and seizure susceptibility were
tested. The most pronounced effect was a decrease in basic synaptic functions in both
slices treated directly ex vivo (50 Hz, 250–320 μT, for 1 hour) observed as a diminution
in the amplitude of evoked potentials. In contrast, whole-body exposure to ELF-EMF
Static, Low-Frequency, and Pulsed Magnetic Fields
heart rate trends over time appears to be associated with a combination of inactivity
(resulting in decreased body temperatures) and reduced physiological arousal. In contrast, Nishimura et al. (2011) suggested that repeated exposure to an ELF-EMF (6 and
8 Hz, 1 μT, 10 V/m, for at least two 10- to 15-minute sessions per week, over a period
of 4 weeks) has a blood pressure–lowering effect on humans with mild-to-moderate
hypertension.
Robertson et al. (2007) reviewed several mechanisms of protection, such as HSPs,
opioids, collateral blood flow, and NO induction, and the evidence supporting the use
of ELF-EMF as a means of providing protection in each of these mechanisms. Although
there are few studies demonstrating direct protection with ELF-EMF therapies, there
are many published reports indicating that ELF-EMF may be able to influence some of
the biochemical systems with protective applications.
McKay et al. (2010) investigated the acute effect of a PEMF (72 Hz, 225 μT, 6.7 mV/m,
for 30 and 60 minutes) on blood flow in the skeletal microvasculature of a male Sprague
Dawley rat model. Acetylcholine (0.1, 1.0, and 10.0 mM) was used to perturb normal
blood flow and to delineate the differential effects of PEMF, based on the degree of vessel
dilation. The authors found that there were no significant effects of PEMF on peak blood
flow, heart rate, and myogenic activity, but a small attenuation effect on anestheticinduced respiratory depression was noted.
3.3.1.6 Neuroendocrine, Visual, and Neurophysiological Systems
Neuroendocrine, visual, and neurophysiological systems also are considered to be
related to the aforementioned magnetic perception (3.3.1.1), analgesia (3.3.1.3), and circulatory system (3.3.1.5). Zhang et al. (2007) examined the effects of long-term exposures to a near-zero magnetic environment on the noradrenergic activities in the brain
stem of golden hamsters. Both the content of norepinephrine (NE) and the density of
NE-immunopositive neurons in tissue decreased significantly after the treatment, and
the effects were found to be progressive with time. These variations may contribute substantially to the behavioral and mood disorders reported in other studies that occur
when animals are shielded from the geomagnetic field.
Jeong, Choi, Choi, et al. (2005) investigated the effect of an ELF-EMF (60 Hz, 2.5 mT)
on convulsions in rats. The authors determined the onset and duration of convulsions
induced by exposure to bicuculline alone or by coexposure to ELF-EMF and bicuculline. Coexposure to ELF-EMF and bicuculline decreased GABA levels in the cortex,
hippocampus, and hypothalamus, whereas exposure to ELF-EMF alone reduced the
levels of GABA only in the hippocampus. These results suggest that ELF-EMF may
modulate bicuculline-induced convulsions due to GABA neurotransmissions in rat
brains.
Varró et al. (2009) examined the effects of ELF-EMF (50 Hz, 250–500 μT) on synaptic
efficacy in the central nervous system. Electrophysiological investigation was carried out
ex vivo in rat neocortical and hippocampal slices, and basic synaptic functions, shortterm plasticity (STP) and long-term plasticity (LTP), and seizure susceptibility were
tested. The most pronounced effect was a decrease in basic synaptic functions in both
slices treated directly ex vivo (50 Hz, 250–320 μT, for 1 hour) observed as a diminution
in the amplitude of evoked potentials. In contrast, whole-body exposure to ELF-EMF