Active Ingredient In Common
Chinese Herb Shown To Reduce Hypertension
New
study in animal model is another step in developing alternative treatments
for those with high blood pressure
(Bethesda, MD) – Some 50 million Americans have
hypertension, that is, blood pressure measuring above the normal range (less
than 120/80 mmHg). If untreated, it can lead to heart attacks, strokes, or
kidney disease. Lifestyle changes are the first-stage treatment for the
disease, but if they fail, medications are prescribed.
Many patients with
high blood pressure have sought relief from complementary and alternative
medicine (CAM). In so doing, many have consumed danshen, a Chinese herb used
in Oriental medicine that promotes blood flow and treats cardiovascular
disease.
Tanshinone IIA is an active ingredient of
danshen. Since tanshinone IIA is widely available, a team of
researchers has used it to investigate if this active ingredient can reduce
blood pressure. In a soon-to-be-released study, using an animal model, the
scientists have found that tanshinone IIA does reduce blood
pressure.
Their study will soon be published in the
American Journal of Physiology – Heart and Circulatory
Physiology (December 15, 2006), doi:10.1152/ajpheart.01027.2006, and
is entitled Endothelial Nitric Oxide Synthase is a Molecular Vascular
Target for the Chinese Herb Danshen in Hypertension. It was conducted by
the team of David D. Kim, PhD, OMD; Fabiola A. Sánchez, PhD; Ricardo G.
Durán, BS; Takehito Kanetaka, MD; and Walter N. Durán, PhD, all of the
Program in Vascular Biology, Department of Pharmacology and Physiology and
Department of Surgery, UMDNJ-New Jersey Medical School, Newark, NJ.
Summary of Methodology
To assess the effect of tanshinone IIA, the
protocol consisted of several parts. The researchers applied the
2-kidney-1-clip protocol to induce renal hypertension in male golden Syrian
hamsters. The animals were anesthetized and a retroperitoneal approach was
used to place a silver clip to constrict
the right renal artery. Sham-operated hamsters and mice underwent the same
procedure, except for the placement of a clip.
Both sets of hamsters received 50 μg of tanshinone IIA/100g
of body weight once a day for two weeks. After the two-week treatment
period, mean arterial blood pressure was measured in the right carotid
artery. To examine the microvascular actions of tanshinone IIA
researchers applied it topically to the hamsters’ cheek pouch or mice
cremaster muscles to achieve the final
concentration of one μg/ml or five μg/ml. After the application of
tanshinone IIA, the experiment was continued for an additional
60-minute period in order to measure arteriolar diameter and peri-arteriolar
nitric oxide concentration.
Results
Tanshinone IIA was found to have
significantly reduced blood pressure in the hamsters. The experimental
constriction of the renal artery increased mean arterial pressure to
161.2±6.9 mmHg relative to 114.3±9.2 mmHg in age-matched hamsters. Treatment
with 50 μg tanshinone IIA/100g body for two weeks reduced the
mean arterial pressure from 161.2±6.9 to 130.0±7.8 mmHg.
The research team also discovered that tanshinone IIA
caused widening of the arterioles in the hamster cheek
pouch microcirculation via enhanced expression of endothelial nitric oxide
synthase. The topical application of tanshinone IIA at one μg/ml
and five μg/ml caused significant dose-related vasodilation, indicated by
the increased agent/control ratio of arteriolar diameters from 1.0 to
1.25±0.08 and 1.57±0.11, respectively, in the hamster cheek pouch. The
increase in arteriolar diameter ratio was significant relative to the
vehicle for each concentration as well as for comparison between the two
concentrations of tanshinone IIA.
Conclusions
As a result of the findings the researchers concluded
that tanshinone IIA: (1) significantly reduced blood pressure in
hamsters, (2) enhanced the expression of endothelial nitric oxide synthase,
(3) increased the production of nitric oxide and (4) induced blood pressure
changes through vasodilation in hamster blood microvessels. While the
mechanisms of how tanshinone IIA or danshen work in hypertension
are not yet fully understood, these results contribute to the effort to
bring complementary and alternative medicine and allopathic care closer
together in the treatment of hypertensive patients.
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JOURNAL PUBLICATION INFORMATION: American
Journal of Physiology – Heart and Circulatory Physiology Articles
in Press, doi: 10.1152/ajpheart.01027.2006.
NOTE TO EDITORS: To schedule an interview with a
member of the research team, please contact Donna Krupa at 301.634.7209
(direct dial), 703.967.2751 (cell) or
dkrupa@The-APS.org.
Physiology
is the study of how molecules, cells, tissues and organs function to create
health or disease. The American Physiological Society (APS) has been an
integral part of this scientific discovery process since it was established
in 1887.
