Vasorelaxing effect in rat thoracic aorta caused by fraxinellone and dictamine isolated from the Chinese herb Dictamnus dasycarpus Turcz: comparison with cromakalim and Ca2+ channel blockers

Sheu Meei Yu, Feng Nien Ko, Ming Jai Su, Tian-Shung Wu, Meei Ling Wang, Tur Fu Huang, Che Ming Teng

研究成果: Article

52 引文 斯高帕斯(Scopus)

摘要

The components of Dictamnus dasycarpus Turcz were tested for their vasorelaxing effect on the rat aorta, and fraxinellone and dictamine were shown to be effective vasorelaxants. In high K+ (60 mmol/l) medium, Ca2+ (0.03 to 3 mmol/l)-induced vasoconstriction was inhibited concentration-dependently by both agents. The IC50 for fraxinellone and dictamine were calculated to be about 25 μmol/l and 15 μmol/l (for Ca2+) concentration of (1 mmol/l), respectively. Cromakalim (0.2-10) μmol/l relaxed aortic rings precontracted with 15 but not 60 mmol/l of K+. Fraxinellone and verapamil were more potent and effective in producing relaxation in 60 mmol/l than in 15 mmol/l K+-induced contraction. However, dictamine was more potent in producing relaxation in 5 mmol/l K+-induced contraction. Nifedipine (1 μmol/l), dictamine (100 μmol/l) and fraxinellone (100 μmol/l) relaxed the aortic contraction caused by KCl or Bay K 8644. The tonic contraction elicited by nor adrenaline (NA, 3 μmol/l) was also relaxed by dictamine (500 μmol/l), but not by fraxinellone (500 μmol/l) in the nifedipine (1 μmol/l)-treated aorta. This relaxing effect of dictamine persisted in endothelium-denuded aorta. Glibenclamide (10 μmol/l) shifted the concentration-relaxation curve of cromakalim, but not that of dictamine, to the right in rat aortic rings precontracted with NA. Dictamine (500 μmol/l) did not affect tonic contraction of NA which are reduced by H-7 (1 μmol/l) in Ca2+ depleted medium. In conclusion, fraxinellone is a selective blocker of voltage-dependent Ca2+ channel, while dictamine relaxed the rat aorta by suppressing the Ca2+ influx through both voltage-dependent and receptor-operated Ca2+ channels.

原文English
頁(從 - 到)349-355
頁數7
期刊Naunyn-Schmiedeberg's Archives of Pharmacology
345
發行號3
DOIs
出版狀態Published - 1992 三月 1

All Science Journal Classification (ASJC) codes

  • Pharmacology

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