We have used mixtures of Fluo-3 and Fura-Red in isolated cardiac
myocytes as well as in others cells. While loading is quite variable
with the AM-ester technique, dialysis via a patch-clamp electrode
produces very consistent and reproducible results.
 
As pointed out by Stepen Cody, signals from AM-loaded cells cannot
be calibrated quantitatively because of these problems. If you are
interested in calibrated Ca signals you need to patch the cells for
loading with the salt form of the indicators.
 
We also found significant binding and changes of the dye properties
in-vivo, suggesting that a in-vivo calibration for the mixture has
to be performed (Lipp, Luescher, Niggli, Cell Calcium, in press).
 
I hope this helps
 
 
Ernst Niggli
Department of Physiology
University of Bern
Buehlplatz 5
3012 Bern
Switzerland
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