Calcium chelators and calcium indicators

Trent A. Basarsky tab at
Thu Apr 13 21:35:44 EST 1995


Can someone explain why some labs include small amounts of EGTA or BAPTA in
their internal patch pipette solutions when they are measuring calcium with 
fura or Fluo-3 that is also being introduced into the cell through the same
patch pipette?

I realize the consequences of internal dialysis when patch clamping, such as
the loss of native calcium buffering, and thus the need to add some buffering 
ability back.  However, how does one determine how much of the measured time
course and / or magnitude of any calcium response is being 'clamped' by these
alien chelators?

I am interested in calcium changes that occur over several seconds, and am concerned
that the addition of 0.5 or 1 mM EGTA to my internal solution (with 100 uM Fluo) will
significantly dampen any calcium changes.

Any information about the use of calcium chelators in this situation would be 

E-mail preferred.

Thank you
Trent A. Basarsky
(tab at

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