J—894对人体血小板激活时胞浆内游离钙浓度的影响

细胞内游离钙浓度在细胞反应的调节中作为第二信使起很重要的作用。本文实验采用荧光钙指示剂quin-2测定血小板胞浆内游离钙浓度Ca^2 ]i的变化。结果表明在1mmol/L外钙的存在下，凝血酶（0.3U/ml）使血小板Ca^2 ]i增高4－5倍。但在外钙缺乏的情况下，凝血酶使血小板Ca^2 ]i增加较少，似科凝血酶增加Ca^2 ]i，部分是通过释放内钙，但主要是通过钙内.J-894通过减少钙内流和释放明显抑制凝血酶引起的血小板Ca^2 ]i的升高，剂量与效应相关。提示J－894可能是一种钙通道阻滞剂。

Effect of J-894 on Cytoplasmic Free Calcium Concentration in Human Platelet Activation

The intracellular free calcium concentration plays a key role as the second messenger in the regulation of cellular reaction.The changes of cytoplasmic free calcium concentration(Ca~(2+)]_i) in human platelets loaded with the fluorescent calcium indicator quin-2 were measured in this study. The result showed that thrombin(0.3 U/ml)raised theCa~(2+)]_i of platelets four to five times in the presence of 1 mmol/L external calcium.but there was a much smaller increase inCa~(2+)]_i in the absence of external calcium.It seems that thrombin increasedCa~(2+)]_i partly by release of internal Ca~(2+),but mainly by stimulating influx.J-894 markedly inhibited the rise ofCa~(2+)]_i in platelets induced by thrombin in a dose dependent manner through decreasing both calcium influx and calcium release.This suggests that J-894 may be a calcium channel blocker.