Indo-1/[Ca++]i calibration

From: Larry Arnold (lwarma@med.unc.edu)
Date: Tue Nov 27 2001 - 15:43:29 EST


I have an investigator who is trying to perform the calibration curve for
intracellular [Ca++] following essentially the method in Current Protocols
in Cytometry except that they purchased the buffers from Molecular
Probes.  While I have done a lot of indo-1 Ca++ I have never myself nor had
any one do this calibration (probably should have by now but I
haven't).  The cells (mouse lymphocytes) look terrible (i.e they all look
dead) after they are placed in the calibration buffers and following
treatment with the agents to open up the Ca++ channels, etc.  FSC is much
decreased and the indo-1 loading levels have dropped to the point that I
have to turn up the PMT voltages a lot to get the indo-1 405 and 485
signals back to where loaded cells in regular media are.  Also, although we
can see the ratio increasing as we raise the [Ca++] it doesn't appear like
that in Current Protocols - the increases are too small.  This strikes me
as not the way to have to do the calibration.  Has anybody done this
calibration (especially with the Mol. Probes buffers)?  Is what I'm seeing
normal or do I have to try to figure out what the heck this investigator is
doing?

Thanks

Larry

Larry W. Arnold, Ph.D.
Associate Professor
Director, Flow Cytometry Facility
Department of Microbiology and Immunology
Lineberger Comprehensive Cancer Center
CB# 7290
University of North Carolina at Chapel Hill
Chapel Hill, NC 27599
Phone: 919-966-1530
FAX: 919-962-8103



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