块的l型钙离子通道孔隙内部和外部Mg2 +鼠phaeochromocytoma细胞。

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郭CC,赫斯P

块的l型钙离子通道孔隙内部和外部Mg2 +鼠phaeochromocytoma细胞。

杂志。1993年7月,466:683 - 706。

PubMed ID

8410712 (在PubMed

]

文摘

1。三到八微摩尔的外部Mg2 +产生离散块内统一的电流通过l型钙离子通道由外部李+ 300毫米。像Ca2 +块,增加李+浓度降低Mg2 +降息和增加Mg2 +不管。2。这些动能变化饱和和明显的离解常数(Kd)对利率在75毫米李+(活动),一样的Ca2 +块。这表明,Mg2 +和Ca2 +产生离散块在同一地点。把利率明显Kd是300毫米,比这小得多的Ca2 +块。这表明Mg2 +施加更排斥在邻近的李+离子(增强)比Ca2 +网站,尽管Mg2 +和Ca2 +都有两项指控。把利率的理论适合还表明,Mg2 +可以退出屏蔽网站的速度每秒几百无增强效果。3所示。 Seventeen to forty-eight micromolar internal Mg2+ produces discrete block of the outward unitary currents carried by 300 mM internal Li+. The off-rates are in general approximately 20 times faster as compared to the Mg2+ off-rates in the inward currents. This finding suggests that Mg2+ in the high-affinity sites can much more easily exit to the outside than to the inside, implying significantly higher energy barriers on the inner side of the high-affinity sites for Mg2+. 4. At least 5-10 mM internal Mg2+ is needed to produce discrete block of the inward unitary currents carried by 215 mM external Na+. The off-rates in such experiments are generally the same as those in the case of external Mg2+ block of inward currents. This suggests that internal and external Mg2+ both reach the same site, namely the high-affinity Ca2+ binding sites in the pore, to produce the discrete block. 5. Other than discrete block, 5-10 mM internal Mg2+ also decreases the size of the inward unitary current. This is most probably due to a fast block at the more internally located low-affinity sites in the pore. The fractional decrease of the currents is voltage dependent and can be fitted by a rectangular hyperbola to calculate the apparent Kd, which increases e-fold per 45 mV hyperpolarization, indicating an electrical distance of 0.3 between the low-affinity sites and the internal pore mouth.(ABSTRACT TRUNCATED AT 400 WORDS)

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药物靶点

药物	目标	类	生物	药理作用	行动
硫酸镁	压敏电阻器l型钙通道(蛋白质组)	蛋白质组	人类	是的	抑制剂 拦截器	细节