摘要
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 the[Ca^(2+)]_i of platelets four to five times in the presence of 1 mmol/L external calcium.but there was a much smaller increase in[Ca^(2+)]_i in the absence of external calcium.It seems that thrombin increased[Ca^(2+)]_i partly by release of internal Ca^(2+),but mainly by stimulating influx.J-894 markedly inhibited the rise of[Ca^(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.
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1 mmol/L 外钙的存在下,凝血酶(0.3 U/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。似乎凝血酶增加[Ca^(2+)]_i,部分是通过释放内钙,但主要是通过钙内流。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。
