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Impairment of Vascular Function of Rat Thoracic Aorta in an Endothelium-Dependent Manner by Shikonin/Alkannin and Derivatives Isolated from Roots ofMacrotomia euchroma

Authors: Yu Wen Cheng; Hui Wen Cheng; Jaw Jou Kang; Chien Ming Hu;

Impairment of Vascular Function of Rat Thoracic Aorta in an Endothelium-Dependent Manner by Shikonin/Alkannin and Derivatives Isolated from Roots ofMacrotomia euchroma

Abstract

The effects of a naphthoquinone analogue, shikonin/alkannin (SA) and derivatives (acetylshikonin and beta,beta-dimethylacrylshikonin), on vascular reactivity were studied with isolated rat aortic rings. At lower concentrations, SA and its derivatives concentration-dependently inhibit the agonist-induced (acetylcholine and histamine) relaxation in PE precontracted aorta in an endothelium-dependent manner with IC (50) values ranging from 0.2 to 1.5 microM. In addition to the effect on agonist-induced vasorelaxation, the Ca (2+) ionophore A23187-induced vasorelaxation was also inhibited or reversed by SA. However, SA had no effect on sodium nitroprusside-induced (guanylate cyclase activator) vasorelaxation. These data suggested that SA and its derivatives might be acting as inhibitors of nitric oxide synthesis in endothelium. At a concentration greater than 10 microM, SA induced contraction of intact but not denuded aorta which could be inhibited by prior treatment with indomethacin, a cyclooxygenase inhibitor. In summary, the results from this study showed that SA and its derivatives inhibited agonist-induced relaxation at lower concentrations and induced vasocontraction at higher concentrations. All the effects seen with SA were endothelium-dependent, however, through different mechanisms. Abbreviations. SA:shikonin/alkannin PE:phenylephrine Ach:acetylcholine SNP:sodium nitroprusside eNOS:endothelial nitric oxide synthase L-NAME: Nw-nitro- L-arginine methyl ester

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Keywords

Dose-Response Relationship, Drug, Plant Extracts, Aorta, Thoracic, Boraginaceae, Plant Roots, Acetylcholine, Rats, Inhibitory Concentration 50, Animals, Endothelium, Vascular, Rats, Wistar, Histamine, Muscle Contraction, Naphthoquinones, Phytotherapy

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citations
This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Citations provided by BIP!
popularity
This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network.
BIP!Popularity provided by BIP!
influence
This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Influence provided by BIP!
impulse
This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network.
BIP!Impulse provided by BIP!
6
Average
Average
Average
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