羊角拗苷对豚鼠心室肌细胞内游离钙离子浓度的影响

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。

Effects of divaricoside on intracellular free calcium concentration in single ventricular myocytes of guinea pig

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. METHODSThe isolated guinea pig cardiomyocytes were loaded with Fura-2/AM to observe the effect of Div 800 nmol·L^-1 on ［Ca²⁺］_i. RESULTSDiv 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.