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 team
of researchers at UC Irvine and a university in China has found
that acupuncture activates a group of nerve cells called the
endorphin system to lower blood pressure and treat some types
of heart disease.
 The research
is part of a growing number of scientific studies that are revealing
exactly how acupuncture works. A 3,000-year-old technique that
originated in China, acupuncture has been used to treat a variety
of health problems, including heart disease.
Dr. John Longhurst,
chair of the Department of Medicine at UCI's College of Medicine,
and Peng Li of Shanghai Medical University in China found that
injections of naloxone - a known inhibitor of the brain's endorphin
system - in cats blocked acupuncture's ability to reduce blood
pressure. The findings appear in the June 1999 American Journal
of Physiology.
The endorphin
system is a group of nerve cells in the brain, named after the
chemicals these cells transmit to relax muscles, dull pain and
reduce panic and anxiety. This system also has been shown to
lower blood pressure and reduce cardiovascular workloads. The
system is often called the body's "natural opiate system,"
because morphine and other opiate drugs affect the same nerve
cells.
"By finding
how acupuncture uses this system to regulate cardiovascular functions,
we will gain a better understanding of how the technique eventually
can be used on some patients to treat high blood pressure and
heart disease," Longhurst said.
In order to
uncover the nervous system pathways that are stimulated by acupuncture,
the researchers increased levels of a chemical called bradykinin
in cats. Bradykinin is produced when the body reacts to infections
and, in general, works against the relaxing effects of the endorphin
system. The chemical triggers inflammation, raises blood pressure
and makes the heart pump harder and faster. Tiny electric probes
that simulate acupuncture needles in the lab reduced bradykinin
levels when the researchers applied the probes to nerve endings
determined by Chinese acupuncture maps to work on heart disease.
The reduced bradykinin levels quickly resulted in lower blood
pressure and allowed the heart to pump less strenuously.
The effects
of these acupuncture probes were negated when researchers introduced
naloxone into the bloodstream; blood pressure rose and heart
pumping action increased. Since naloxone blocks nerve cells in
the endorphin system, the scientists concluded that acupuncture
was doing its work by stimulating the body's natural endorphins.
"Endorphins
have been known to help the body prevent heart disease, but we've
never seen how they can be affected by acupuncture," Longhurst
said. "Although the technique has been used for thousands
of years, these findings help us merge what western medicine
has taught us with the tradition of Chinese techniques."
Acupuncture
treatments have lowered blood pressure in some patients and in
certain instances have effectively treated a disorder called
cardiac ischemia, which is caused by an inadequate supply of
blood to the heart muscle cells. The disorder can be very painful
and lead to more serious cardiovascular disorders.
The researchers
will next try to determine which nerve cells are used by acupuncture
in the endorphin pathways to treat heart disorders, and examine
whether other parts of the nervous system help contribute to
acupuncture's effects on the cardiovascular system. Stephanie
Tjen-a-Looi of UCI's College of Medicine, Dong Chao and Lin Shen
of Shanghai Medical University and Koullis F. Pitsillides of
UC Davis' Division of Cardiovascular Medicine assisted the team
in its research. 
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uci.edu.