Modern Blood Vessel
Measurements Test An Age Old Belief That Magnetic Fields Can Influence
Blood Flow
Was Paracelsus correct about
human blood flow?
April 9, 2003 (San Diego, CA) -- Some 2,000
years, the Chinese first advocated the use of magnetic therapy. In the
Middle Ages, Paracelsus (1493-1543), a physician and alchemist, came to the
conclusion that since magnets have the power to attract iron, perhaps they
can also attract diseases and leach them from the body.
Even in the 21st
century, the magnetic therapy industry generates approximately $500 million
in income, in part, as a result of aggressive marketing strategies that use
professional athletes to promote the healing effects of magnetic therapy
products. Supporters of this alternative medicine cite anecdotal evidence
that this treatment is effective; however, scientific evidence supporting
the efficacy of magnetic therapy is somewhat lacking.
There is, however, growing evidence that magnetic field
therapy can influence physiological processes such as bone formation, action
potential generation, edema formation, and tumor apoptosis. Studies have
also suggested that magnetic field application can influence cutaneous
circulation and blood pressure in rats, but little information is available
regarding the impact of magnetic fields on microvascular blood flow in
general, and resistance arterioles in skeletal muscle in particular.
Changes in microvascular tone have been implicated as net effects of
magnetic field application and although study models have included in
vitro, in vivo and clinical trials, no direct measurement of blood
vessel diameter in skeletal muscle in vivo has been completed to date.
A New Study
Researchers from the University of Virginia set out to
demonstrate the effects, if any, of a static magnetic field exposure on
microvascular tone in skeletal muscle in vivo via direct measurement of
microvascular diameters. The authors of “Magnet Therapy – The Power to
Heal” are Thomas Skalak, PhD, and Cassandra Morris, both from the Department
of Biomedical Engineering at the University of
Virginia, Charlottesville, VA. Their findings are being presented at
Experimental Biology 2003, a meeting sponsored by the American
Physiological Society, being held April 11-15, 2003, at the San Diego
Convention Center, San Diego, CA.
Key to the research study is the notion that local and
overall blood flow and function can be directly related to blood vessel
diameter based upon changes in flow resistance. Claims have been made that
magnet therapy can increase blood flow to the site of injury, relieving
inflammation, edema and other pathophysiological conditions related to
either excess or insufficient blood flow. Accordingly, these experiments
were designed to determine the direct effect of static magnetic fields (SMF)
on blood vessel diameter, and therefore the overall influence on network
resistance and subsequent effect on localized blood flow.
Methodology
Changes in
microvessel diameters in response to the magnetic field were measured in
intact skeletal muscle in vivo. The spinotrapezius muscle of female
Sprague-Dawley rats was exteriorized and exposed to a localized SMF for 15
minutes. Images were taken before exposure, after exposure and 15 and 30
minutes post-exposure or “recovery.” These images were later digitized and
arteriolar vessel diameters measured.
Additionally, a
pharmacological stimulus was topically applied to establish near maximal
dilation of the microvasculature. This data was used to generate reference
diameters for calculation of microvascular tone. Comparison of the
calculated tone values between timepoints facilitated analysis of the
overall response to the magnetic field.
Results
The results indicate that the initial, resting tone of
the microvasculature can dictate the overall response of the skeletal muscle
microvasculature to application of a static magnetic field. Microvessels
that are initially dilated respond to the magnetic field by constricting,
and microvessels that are initially constricted respond by dilating. This
response is regarded as a biphasic response to the field application.
Interestingly, it was found that this biphasic response was dependent upon
the initial size or diameter of the vessel. The entirety of the response
was manifested in microvessels with initial diameters less than 30mm.
These size vessels generally encompass the terminal arterioles, which are
thought to be intimately involved in the alteration of network flow
resistance because they are situated in a position to directly regulate
capillary blood flow. Relatively small changes in vessel diameter can
influence the network resistance and lead to substantial changes in tissue
perfusion. While no direct measurements of flow were acquired in the
present study, the results support the conclusion that SMF exposure can have
a significant impact on blood flow as well as microvascular tone.
Conclusions
From this study, it can be concluded that a 700G static
magnetic field exposure has a restorative, biphasic effect on microvascular
tone in skeletal muscle acting to normalize the tone following exposure.
This effect is primarily mediated by the smaller resistance arterioles.
These results suggest that application of this field to ischemic (vasoconstricted
microvascular state) or edematous (vasodilated microvascular state) soft
tissue injuries would result in modulation of tissue perfusion, thus acting
as an alternative or additional therapy for these conditions.
-end-
The American
Physiological Society (APS) is one of the world’s most prestigious
organizations for physiological scientists. These researchers specialize in
understanding the processes and functions underlying human health and
disease. Founded in 1887 the Bethesda, MD-based Society has more than
10,000 members and publishes 3,800 articles in its 14 peer-reviewed journals
each year.
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Editor’s
Note: For receive a copy of the abstract, or to schedule an interview with a
member of the research team, please contact Donna Krupa at 703.967.2751
(cell), 703.527.7357 (office) or at
djkrupa1@aol.com.
