【摘要】 目的观察羊角拗苷(Div)对豚鼠心室肌细胞内游离钙离子([Ca2+]i)浓度的影响,以探讨Div正性肌力作用的机制。方法Fura-2/AM荧光探针标记豚鼠心室肌细胞,应用荧光离子成像系统观察Div800nmol.L-1对心室肌细胞[Ca2+]i的影响。结果在正常台氏液中,Div使心室肌细胞[Ca2+]i显著升高(243±36)%,在无钙液中对[Ca2+]i无明显影响。在无Na+、无K+台氏液中,Div使[Ca2+]i升高(96±20)%。给予L型钙通道阻滞剂CdCl2100μmol.L-1预处理后,Div仍使[Ca2+]i升高(63±10)%。给予T型钙通道阻滞剂NiCl240μmol.L-1预处理后,Div引起的[Ca2+]i升高基本被阻断。结论体外应用Div800nmol.L-1时使豚鼠心室肌细胞[Ca2+]i升高,该升高作用依赖于细胞外Ca2+的存在,可能主要由T型钙通道介导,L型钙通道和Na+-Ca2+交换蛋白亦参与其中。其正性肌力作用与心室肌细胞[Ca2+]i升高有关。更多还原

【Abstract】 AIM To study the effect of divaricoside(Div)on intracellular free calcium concentration([Ca2+]i)in guinea pig ventricular myocytes in order to investigate the mechanism of its positive inotropic effect.METHODSThe isolated guinea pig cardiomyocytes were loaded with Fura-2/AM to observe the effect of Div 800 nmol·L-1 on [Ca2+]i.RESULTSDiv obviously increased cardiomyocyte [Ca2+]i by(243±36)% in Tyrode’s solution,but had no effect in calcium-free Tyrode’s solution.In sodium,potassium-free Tyrode’s solution,Div increased [Ca2+]i by(96±20)%.Pretreatment with CdCl2(L-type calcium channel blocker)100 μmol·L-1,Div increased [Ca2+]i by(63±10)%.While pretreatment with NiCl2(T-type calcium channel blocker)40 μmol·L-1,the effect of Div on [Ca2+]i was inhibited.CONCLUSION The elevation of [Ca2+]i involves in the positive myocardium inotropic effect of Div.The Div induced-[Ca2+]i elevation depends on the presence of extracellular calcium,possibly mediated mainly by T-type calcium channel and partly related to L-type calcium channel and Na+-Ca2+ exchanger.更多还原