甲基对硫磷诱发大鼠肝细胞内钙浓度升高的初步机制研究

Mechanisam of Methylparathion-induced Intracellular Ca^(2+)Increase

应用激光扫描共聚焦显微镜观察甲基对硫磷(M ETHYLPARATH ION,MP)对正常大鼠肝细胞株(BRL)内游离钙浓度([CA2+]I)的影响。实验结果表明,在正常生理盐溶液(N-PSS)中,MP能引起细胞内的钙升高,并呈浓度依赖性;在无钙生理盐溶液(0 CA2+-PSS)中,400 PMOL/L MP不显著改变细胞内的钙浓度。用不同的非选择性阳离子通道阻断剂(300ΜMOL/L GD3+,2 MMOL/L SR2+,2 MMOL/L N I2+)作用于由MP引起的钙升高时,发现均能有效地抑制钙升高,其中N I2+的抑制效果最为明显。同时MP引起的钙升高的时程远远大于ATP的作用。以上结果显示,MP对BRL细胞胞内的CA2+具有升高作用,此作用可能是MP激活非选择性阳离子通道,并最终导致细胞膜上的其它钙离子通道开放。

The present studies investigated the effects of Methylparathion （MP） on the intracellular Ca^2＋ in the BRL cells. The cells were loaded with 10 μmol/L Fluo3/AM, and measured the [ Ca^2＋ ]i by laser confocal scanning microscope （LCSM）. The results suggested that MP concentration-dependence induced a increase of [ Ca^2＋ ]i in normal physiology saline solution （N-PSS） ; When the solution changed to 0Ca^2＋ -PSS, 400 × 10^-6 MP have no effect on the [ Ca^2 ＋ ]i. But there was a significant increase of [ Ca^2＋ ] i while the solution was changed from 0Ca^2＋-PSS to N-PSS. The MP-induced [ Ca^2＋ ]i was found to be blocked by several non-selective cation channel blockers, such as 300μmol/L Gd^3＋ , 2mM Sr^2＋ , and 2mM Ni^2＋. We also observed the difference between ATP- induced [ Ca^2＋]i and MP-induced [ Ca^2 ＋ ]i, the MP-induced a longer increase of [ Ca^2 ＋ ]i than ATP did. These results suggested that MP could activated the non-selective cation channels, then lead to a significant Ca^2＋ influx through Ca^2＋ channels.