Jamie,
there are a number of different procedures available to conduct an
ATPase stain.  The method that you adopt depends upon what information
you want out of your stain.  If you are interested in fibre typing a
muscle sample you may want to make a distinction between Type I and II
fibres only.  In this case you would only need to conduct one
pre-incubation and therefore only need one slide.  Whereas, if you want
to make a distinction between Type IIa and IIb fibres, you would
probably be better off using two pre-incubation media of varying pH's.
There are some procedures available that claim to segregate the three
sub-types at the one pH (thus, one pre-incubation or no pre-incubation
when used in presence of alcohol), however I have found that if the pH
is slightly out, you are stuck with having to go back to your block and
cutting a new section, so you will obviously need a very accurate pH
meter to conduct this staining.

My advice would be to conduct the pre-incubation at 4.3 and 4.6, and
then incubate at 9.4, and then maybe run another slide at a
pre-incubation pH of 4.54 which is believed to show all three subtypes.
Once you feel confident with the 4.54 pre-incubation, you just need to
use the one pre-incubation media.

Alternatively you may want to read the following articles:

Mabuchi, K. & Sreter, F.A. (1980).  Muscle and Nerve, 3, p. 233-239.
Tunell, G.L. & Hart, M.N. (1977).  Arch. Neurol., 34, p. 171-173.

Hope this helps.
If you want to have a look at our protocol, I can send that to you
personally, I just didn't want to clog up the server by sending it
through.

All the best,
Tim.
-----------------------------------------------------------------
Timothy J. Fairchild B.Sc. (Hons)
PhD Candidate
Co-ordinator for Centre of Athletic Testing
Department of Human Movement and Exercise Science
Nedlands, Western Australia 6907
Telephone: (+61 8) 9380 2793
Facsimile:  (+61 8) 9380 1039
Email: timf@cyllene.uwa.edu.au
http://www.general.uwa.edu.au/~hmweb/index.htm