钩藤碱对猪冠状动脉平滑肌舒缩作用的影响及其机制

目的观察钩藤碱对离体猪冠状动脉血管的作用,并探讨其作用机制。方法采用血管环张力测定技术及全细胞穿孔膜片钳技术分别观察钩藤碱对离体猪冠状动脉血管环张力的影响以及对大电导钙激活钾通道(BKCa)的作用。结果血管环张力实验显示钩藤碱能够明显舒张(89.94±1.18)%,n=7]高钾(40mmol/L)去极化所致的冠状动脉血管收缩,而K+通道阻断剂四乙基胺(TEA)不能抑制钩藤碱的舒血管作用,提示K+通道几乎不参与钩藤碱对猪冠状动脉血管的舒张。在全细胞穿孔膜片钳模式下,钩藤碱(100μmol/L)可显著抑制猪冠状动脉平滑肌细胞的BKCa通道(48.22±4.24)%,n=6],BKCa通道介导的自发性瞬时外向电流(STOCs)的幅度和频率也分别下降了(45.74±6.26)%和(87.98±6.39)%(n=5)。结论钩藤碱可明显舒张猪冠状动脉血管,而对全细胞BKCa通道具有明显的抑制作用,K+通道的激活在钩藤碱的舒血管机制中所起的作用不大。

Mechanism of Rhynchophylline-induced relaxation in porcine coronary artery

Objective To examine the effect of rhynchophylline(Rhy) on porcine coronary artery rings and to investigate the mechanism involved.Methods The isometric tension of coronary arterial rings taken from porcine hearts was measured and its response to Rhy(100 μmol/L)was studied.The effect of Rhy on BK_Ca currents was observed by whole-cell perforated patch clamp configuration.Results Rhy(100 μmol/L) significantly antagonized(89.94±1.18)%,n=7] the coronary artery tension increase precontracted with KCl(40 mmol/L),K~+ channels blocker TEA(10 mmol/L) failed to prevent the relaxation effect of Rhy.Under the perforated whole-cell patch-clamp configuration,Rhy(100 μmol/L) significantly inhibited BK_Ca currents48.22%±4.24%,n=6].The mean amplitude and frequency of spontaneous transient outward currents(STOCs) or transient BK_Ca currents were also remarkably inhibited by(45.74±6.26)% and(87.98±6.39)%(n=5),respectively.Conclusion Rhy relaxes recontracted porcine coronary artery;K~+ channel activation is almost not involved in coronary artery relaxation induced by Rhy.