ehom1 at cc.swarthmore.edu (Erik Forbes Y. Hom) writes:
>Does anyone know what the pH, salt environment, etc. (anything would be
>helpful) of neuronal cell nuclei and in the cytoplasm is like? I know that
>subfractionation studies can be very misleading - has there been any
>attempt to determine this information by other means (fluorescent dyes,
>perhaps)? Info on either subcellular region would be much appreciated.
>PS I'm interested in these cells in Drosophila
>Thanks!
Studies with ion-sensitive microelectrodes in a variety of neurons and
muscle cells give the following best guesses; cytoplasmic pH:7.0-7.3; Na:
5-10mM; K:80-200mM; Ca; 10 -7 M. One of the best places to look for good
values for a specific cell or animal is in the electrophysiology
literature using whole-cell patch clamp, because these people have to
design pipet solutions that mimic cytoplasmic ion concentrations. Try
checking recent articles by Lou Byerly in the Journal of Physiology
(Lond.); he does this on Drosophila neurons. Difficulties are often
found in finding an appropriate anion (Cl is often toxic; glutamate or
aspartate is often used), and in balancing osmolarity (sorbitol may be a
good choice to balance osmolarity).
Bill Moody
