inquiry: neuronal cell pH, etc.

William Moody profbill at u.washington.edu
Thu Jul 28 14:27:09 EST 1994

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

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

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