Cultured cells at constant pH?

[Ian A. York]

This is probably a simple question, but I don't know where to start
looking.

I want to grow tissue culture cells at a range of constant pHs for several
days.  The pH doesn't have to be fabulously accurate, but I don't want it
to start dropping dramatically as the cells become denser.  I'd like to
try a range of, oh, I don't know, let's say 6.3 - 7.3 or so.  

Are there media that will do this?  Where can I find recipes?

Ian
-- 
      Ian York   (iayork at panix.com)  <http://www.panix.com/~iayork/>
      "-but as he was a York, I am rather inclined to suppose him a
       very respectable Man." -Jane Austen, The History of England