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KMID : 0861020100250040017
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Korea Journal of Herbology
2010 Volume.25 No. 4 p.17 ~ p.21
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Differential Mechanisms of Vascular Relaxation between Alcohol Steamed Rhei Tangutici Radix et Rhizoma and Rhei Tangutici Radix et Rhizoma
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Yang Jae-Kyung
Shin Heung-Mook
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Abstract
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Objectives: The aim of this study was to evaluate the differential mechnism of vasodilation of alcohol steamed Rhei Tangutici Radix et Rhizoma. (ART) and Rhei Tangutici Radix et Rhizoma. (RT) in rat thoracic aorta.
Methods: Rat aortic ring preparations were mounted in organ baths with oxygenated (95% O2-5% CO2) Krebs-Ringer bicarbonate solutions at 37±0.5 ℃and subjected to contractions or relaxations.
Results: ART exerted vasorelaxation on phenylephrine(PE)-induced contraction in a dose dependent manner. Vasorelaxation effects of ART and RT were endothelium-independent. In the Ca2+-free high KCl (60 mM) baths, the contraction of aortic rings induced by accumulative addition of Ca2+ (0.3-10.0 mM) was significantly reduced by pre-treatment with both ART and RT for 10 min. The magnitude of vasodilatation was biggerin ART. Moreover, verapamil (0.001 μM) and diltiazem (10 μM), voltage operative Ca2+channel blockers, attenuated the relaxation effect of ART but not that of RT. In the absence of extracellular Ca2+, pre-incubation of the aortic rings with RT (1.0 ㎎/㎖) significantly reduced the contraction caused by PE but not that of ART. K+ channel inhibitors such as glibenclamide (Gli, 10-5M), tetraethylammonium (TEA, 1 mM) and 4-aminopyridine (4-AP, 0.2 mM) significantly reduced the ART’s vasorelaxation efficacy, but not that of RT. However, the relaxation effects of ART and RT were not inhibited by pre-treatment with indomethacin (10-5 M), and atropine (10-6 M).
Conclusions: These results suggest that the endothelium-independent relaxation is due to inhibition of Ca2+ influx via the suppression of Ca2+ release from intracelluar store in RT but via both voltage operative Ca2+channel blockage and K+ channel activation in ART.
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KEYWORD
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Rhei Tangutici Radix et Rhizoma, alcohol steamed Rhei Tangutici Radix et Rhizoma, vasorelaxation, inhibition of Ca2+ influx
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