论文部分内容阅读
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。
Objective To observe the effect of crotin (Div) on intracellular free calcium ion ([Ca2+]i) in ventricular myocytes of guinea pigs and explore the mechanism of Div positive inotropic effect. Methods The guinea pig ventricular myocytes were labeled with Fura-2/AM fluorescent probes. The effect of Div800nmol.L-1 on [Ca2+]i in ventricular myocytes was observed by fluorescence imaging system. RESULTS: In normal Tyrode’s solution, Div induced a marked increase in [Ca 2+ ] i (243 ± 36)% in ventricular myocytes and no effect on [Ca 2+] i in calcium-free fluid. In the Na+-free, K+-free Tyrode’s solution, Div increased [Ca2+]i by (96±20)%. After pretreatment with L-type calcium channel blocker CdCl2100μmol.L-1, Div still increased [Ca2+]i by (63±10)%. Pretreatment with T-type calcium channel blocker NiCl240μmol.L-1 resulted in a blockade of [Ca2+]i elevation induced by Div. Conclusions [Ca2+]i in ventricular myocytes of guinea pigs increased when Div800 nmol.L-1 was applied in vitro. This increase was dependent on the presence of extracellular Ca2+, which may be mediated mainly by T-type calcium channels, L-type calcium channels and Na+- Ca2+ exchange protein is also involved. Its positive inotropic effect is related to the elevation of [Ca2+]i in ventricular myocytes.