Neurotransmitter Current Not Flowing Through Ion Channels

[antiquity]

Wise, what's your opinion on this?

Source: Cornell University
Date: September 5, 2007

Neurotransmitter Current Not Flowing Through Ion Channels
Science Daily — 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.

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....

http://www.sciencedaily.com/releases...0830102617.htm

[Wise Young]

Wise, what's your opinion on this?

Source: Cornell University
Date: September 5, 2007

Neurotransmitter Current Not Flowing Through Ion Channels
Science Daily — 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.

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....

http://www.sciencedaily.com/releases...0830102617.htm

Let me first explain what this is all about. The study is not referring to the current that occurs across cellular membranes when neurotransmitters open ionic channels. What it is referring to is a current that was claimed to occur when neurotransmitter vesicle fuse with the membrane and release their contents into the extracellular space. The observed current was probably an artifact during the patch-clamp recording of the membrane. In any case, I think that the question is not very important from a mechanistic or therapeutic point of view. The current was not thought to be doing very much.

Wise.