Re: help:potassium reporter
Jacek Witkowski (jawit@amed01.amg.gda.pl)
Tue, 7 Feb 1995 17:09:17 +0100 (MET)
Dear Heinz:
In response to your query - the only potassium detecting
fluorochrome on the market so far is the PBFI manufactured by Molecular
Probes. Unfortunately, it requires the UV. Unless somebody knows better,
you cannot measure potassium ion fluxes across the membranes using
visible excitation as yet. I have the same problem and I am now
considering upgrading my EPICS C argon laser to the UV capability (buying
all these replacement mirrors etc...).
To approach the problem of K+ flux from the transmembrane potential
side, you will have to consider other ion currents interferring with your
potential measurement. You might want to use selective channel blockers
to block sodium (TTX? STX or new generation blockers?) and calcium
current (this one can be quite substantial!)
I agree with Howard Shapiro that you can use oxonol dyes to measure the
TMP by flow. I would NOT, however, recommend cyanine dyes in mammalian
cells - too much of the signal is trapped in the mitochondria (obscuring
the membrane measurements).
My address (in case you may want it):
Jacek M. Witkowski
Department of Histology and Immunology
Medical University of Gdansk
80-211 Gdansk, Poland
e-mail: jawit@amed01.amg.gda.pl
All the best - Jacek
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