INOSITOL TRISPHOSPHATE ACTIVATES A VOLTAGE-DEPENDENT CALCIUM INFLUX IN XENOPUS OOCYTES
INOSITOL TRISPHOSPHATE ACTIVATES A VOLTAGE-DEPENDENT CALCIUM INFLUX IN XENOPUS OOCYTES
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DOI：
10.1098/rspb.1987.0033
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发表时间：
1987-06-22
期刊：
影响因子：
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通讯作者：
MILEDI, R
中科院分区：
文献类型：
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作者：
PARKER, I;MILEDI, R
将三磷酸肌醇 (IP3) 注射到非洲爪蟾的卵母细胞中，会导致膜超极化时出现短暂的内向 (Tin) 电流。该电流主要由氯离子携带，但显示取决于细胞外钙，因为它可以通过去除沐浴液中的钙或添加锰来消除。使用水母发光蛋白作为细胞内钙指示剂的记录表明，在细胞内注射 IP3 以及激活被认为介导 IP3 升高的神经递质受体后，超极化会激活钙流入。此外，通过用钡代替浴液中的钙，可以在超极化过程中记录内向钡电流。我们得出结论，细胞内 IP3 调节一类钙通道的活性，从而允许钙在超极化时流入。在正常的林格溶液中，由于卵母细胞膜中存在大量钙依赖性氯离子通道，这会导致氯离子电流的产生。
Injection of inositol trisphosphate (IP3) into oocytes of Xenopus laevis induces the appearance of a transient inward (Tin) current on hyperpolarization of the membrane. This current is carried largely by chloride ions, but is shown to depend on extracellular calcium, because it is abolished by removal of calcium in the bathing fluid or by addition of manganese. Recordings with aequorin as an intracellular calcium indicator show that a calcium influx is activated by hyperpolarization after intracellular injection of IP3 as well as after activation of neurotransmitter receptors thought to mediate a rise in IP3. Furthermore, by substituting barium for calcium in the bathing solution, inward barium currents can be recorded during hyperpolarization. We conclude that intracellular IP3 modulates the activity of a class of calcium channels, so as to allow an influx of calcium on hyperpolarization. In normal Ringer solution this then leads to the generation of a chloride current, because of the large numbers of calcium-dependent chloride channels in the oocyte membrane.