原文报道：
Neurotransmitter current not flowing through ion channels
In studying how neurotransmitters travel between cells -- by analysis of events in the dimensions of nanometers -- Cornell researchers have discovered that an electrical current thought to be present during that process does not, in fact, exist.
These results were reported July 22 in the online edition of the journal Nature Cell Biology by Cornell researchers Liang-Wei Gong and Manfred Lindau, applied and engineering physics, as well as their colleague Guillermo Alvarez de Toledo at the University of Seville, Spain.
Lindau explained that neurotransmitters and hormones are stored in neurons -- nerve cells -- in small packets, membrane-bound vesicles, typically 30 to 300 nanometers in diameter (a nanometer is one-billionth of a meter). When a cell is stimulated by electrical activity, calcium ions enter the cell and the vesicles release their contents by fusion with the plasma membrane surrounding the cell.
Prior experiments had suggested that the vesicles contain ion channels that carry charged neurotransmitters from the cell vesicle out of the cell, generating an electrical current flowing out of the cell.
Lindau and colleagues report in their paper that there is no such current present. Their experiments further showed that, instead, the charge compensation is generated by the influx of positive sodium ions from the outside into the vesicles, a process known as electrodiffusion.
"Therefore, the ion channels in these vesicles must play a different role that is yet to be discovered," Lindau explained.
Source: Cornell University
Prior experiments had suggested that the vesicles contain ion channels that carry charged neurotransmitters from the cell vesicle out of the cell, generating an electrical current flowing out of the cell.
Lindau and colleagues report in their paper that there is no such current present. Their experiments further showed that, instead, the charge compensation is generated by the influx of positive sodium ions from the outside into the vesicles, a process known as electrodiffusion.
"Therefore, the ion channels in these vesicles must play a different role that is yet to be discovered," Lindau explained.
Source: Cornell University
译文：
最近来自美国Cornell大学的科学家进行了一项针对神经传递素如何在细胞之间传递的研究，通过进行纳米尺度的分析，研究小组最终发现，原来人们普遍认为应该在这一过程中表现出来的电流事实上并不存在。
来自Cornell应用和工程物理系的科学家Lindau解释说，这些神经传递素和激素以被细胞膜包裹的小泡状物的形式存在于神经细胞中，这些小泡状物的直径一般在30-300纳米之间（一纳米相当于十亿分之一米）。当一个细胞被电信号刺激之后，钙离子将会进入细胞，然后这些小泡状物会通过溶解包围在细胞周围的质膜来释放出其中的物质。
之前的相关实验曾经证实，这些小泡状物中含有离子通道，通道可以将来自小泡中的带电神经传递素携带到细胞之外，从而在细胞外产生电流。
然而，Lindau和同事在他们的文章中表示事实上并不存在这样的电流。相反他们的实验进一步显示，电荷补偿是由于带有正电的钠离子从泡外流入泡内而产生的，这种现象被称为电扩散。
Lindau表示：“因此这些存在于小泡中的离子通道肯定起着另一种尚未被发现的作用。”
