异钩藤碱体外对家兔血小板聚集和胞浆游离钙离子浓度的影响

目的研究异钩藤碱对血小板内游离钙离子浓度(Ca2+]i)的影响,以探讨其抗血小板聚集作用的可能机制。方法比浊法测定家兔血小板聚集功能;双波长Fura-2荧光法测定血小板胞浆Ca2+]i。结果异钩藤碱0.33~1.30mmol.L-1体外给药对ADP和凝血酶引起的血小板聚集有浓度依赖性的抑制作用。存在细胞外钙时,异钩藤碱对基础状态血小板的Ca2+]i和ADP及凝血酶诱导的Ca2+]i水平有浓度依赖性的降低作用,而无细胞外钙存在时,则均无明显影响,表明其可抑制血小板的外钙内流,对内钙释放无明显抑制作用。结论异钩藤碱可抑制血小板聚集,其作用机制可能与其抑制血小板胞浆Ca2+]升高有关。

Effect of isorhynchophylline on platelet aggregation and cytoplasmic free calcium level in rabbit platelets in vitro

AIM Observing the effect of isorhynchophylline on cytoplasmic free calcium level (［Ca²⁺］_i) of platelets, to investigate the possible mechanism of its anti- platelet aggregation. METHODS Rabbit platelet aggregation and platelet ［Ca²⁺］_i were determined by Born method and double beam fluorescence spectrophotometric method, respectively. RESULTSIsorhynchophylline 0.33-1.30 mmol·L^-1 administered in vitro visibly inhibited the rabbit′s platelet aggregation induced by ADP (15 μmol·L^-1) and thrombin (3 kU·L^-1) in a concentration- dependent manner. In the presence of extracellular Ca²⁺, isorhynchophylline inhibited the resting ［Ca²⁺］_i and the increased ［Ca²⁺］_i induced by ADP (15 μmol·L^-1) and thrombin (3 kU·L^-1) in a concentration-dependent manner, but had no effect on ［Ca²⁺］_i in the absence of extracellular Ca²⁺, which indicated that isorhynchophylline inhibited extracellular Ca²⁺ influx in platelets, but had no inhibitory effect on intracellular Ca²⁺ mobilization. CONCLUSION Isorhynchophylline markedly inhibits the rabbit platelet aggregation, and the mechanism may be related to its depression on the rise of platelet ［Ca²⁺］_i.