Help with interpreting a bio article?

Question

can someone help me with this? its a letter to the editor and is about what happens to the cell membrane when voltage is applied but i cant seem to understand what its talking about. it said something about the lipids in the inside of the membrane, and it reorients them? but what exactly happens? are the lipids disrupted enough so that other polar molecules can enter the cell?

http://www.biophysj.org/cgi/content/full/81/3/1823

thanks a billion

Answer 1

It appears that they are evaluating lipid headgroups (the primary lipid components making up a cell's outer membrane -- heads outward with tails inward toward the cytosol) orientation as a function of applied membrane voltage. I am assuming at this point that the applied membrane voltage is of the AC type with a specific wave form shape and frequency, voltage level.  They seem to suggest that there is some kind of linear relationship between applied membrane voltage and the orientation of lipid headgroups in specific areas of the membrane itself, along with change in ion transport channels, etc. Apparently, measurements were made after allowing for some period of membrane restablization. It appears that whatever alteration they make in the cell membrane structure by applied voltage to the membrane, is reversible by reversing voltage polarity (perhaps phase of the applied signal).

The wording of the article is a bit abstract, but it appears to me that they are looking at how cellular membrane structure changes as a function of applied voltage across the membrane. This could be in relations to how cell membranes can be made to take in large molecules as a function of voltage, that otherwise couldn't pass across the membrane on their own; also, it is a well known fact that cells (when placed in close contact) can be made to "fuse" by applying the right signal voltage at the right strength and frequency. Also, cells can be made to take up plasmids and even bits of DNA directly by applying a voltage across the membrane that forces "pores" in the membrane to open up widely.  Additionally, voltage can be applied to an unfertilized egg cell's membrane and it will trigger a development program within the egg that can lead to embryogenesis.

See: Electro Cell Manipulator ECM 2001

http://www.btxonline.com/products/electr...

A comparison of intracellular changes in porcine eggs after fertilization and electroactivation

http://dev.biologists.org/cgi/reprint/11...

That's my best guess.

  

Answer 2

argh, too much to read. Sorry.

Answer 3

I am not entirely sure, but I believe it has something to do with a property called electroporesis. What happens in electroporesis is that when electricity is applied to the cell's lipid bilayer membrane, the membrane is disrupted and holes form in them. This property allows scientists to create holes in cells and insert foreign plasmids for gene studies or the mass production of things like insulin.