- 作者: C.M. Teng; S.M. Yu; C.P. Pan; S.S. Lee
- 作者服務機構: a Pharmacological Institute and; b School of Pharmacy, College of Medicine, National Taiwan University, Taipei, Taiwan, ROC
- 中文摘要: --
- 英文摘要: The vasorelaxing effect of N-benzylsecoboldine on the rat thoracic aorta was investigated, and we also compare it with nifedipine and cromakalim. In high K+ (60 mM)medium, Ca2+ (0-03-3 mM)-induced vasoconstriction was inhibited concentration-dependently by N-benzylsecoboldine, whereas this contraction was not altered by cromakalim. Cromakalim relaxed aortic rings precontracted with 15 but not 60 mM of K+. N-benzylsecoboldine and nifedipine were more potent and effective in producing relaxation in 60 mM than in l5 mM K+- induced contraction. N-benzylsecoboldine was found to be an α1-adrenoceptor- blocking agent in rat thoracic aorta as revealed by its competitive antagonism of phenylephrine (PE)-induced contraction (pA2=6.31±0.04, pA10=5.41±0.03). This relaxing effect of N-benzylsecoboldine was not antagonized by indometha- cin or methylene blue, and still persisted in endothelium-denuded aorta or in the presence of nifedipine (1μM). The increase of inositol monophosphate caused by PE in rat aorta was significantly suppressed by N-benzylsecoboldine, but not by nifedipine or cromakalim. High concentration of N-benzylsecoboldine (100 μM) did not affect the contraction induced by B-HT 920, serotonin or PGF2α. Glibenclamide and charybdotoxin did not affect the relaxation of N-benzyl- secoboldine in aortic rings precontracted with PE. Neither cGMP nor cAMP lev- els were changed by N-benzylsecoboldine. We suggest that N-benzyl- secoboldine relaxes rat thoracic aorta by suppressing the Ca2+ influx and also has antagonistic effect on α1-adrenoceptors.
- 中文關鍵字: --
- 英文關鍵字: Vasorelaxation; N-benzylsecoboldine; Ca2+ channel blocker; α1-Adrenoceptor antagonist; Rat aorta