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.
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 |¨¬g 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 |¨¬g/ml or five |¨¬g/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 |¨¬g 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 |¨¬g/ml and five |¨¬g/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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Their study will soon be published in the
American Journal of Physiology ¡§C 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. S¡§¡énchez, PhD; Ricardo G. Dur¡§¡én, BS; Takehito Kanetaka, MD; and
Walter N. Dur¡§¡én, PhD, all of the Program in Vascular Biology, Department of
Pharmacology and Physiology and Department of Surgery, UMDNJ-New Jersey Medical
School, Newark, NJ.
JOURNAL PUBLICATION INFORMATION: American Journal
of Physiology ¡§C Heart and Circulatory Physiology Articles in Press, doi:
10.1152/ajpheart.01027.2006.
Physiology is the study of how molecules,
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Physiological Society (APS) has been an integral part of this scientific
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