In situ Ca2+ titration in the fluorometric study of intracellular Ca2+ binding

- Endogenous Ca2+ buffers can be probed in situ by titrating Ca2+ binding sites.
- Our extension exploits information available in Ca2+ fluorometry more effectively.
- We analyzed fluo-8 Ca2+ 2-photon imaging data from pituitary nerve terminals.
- We estimated the excluded volume and endogenous Ca2+ buffer Kd and concentration.
- An estimate of the in situ Kd of fluo-8 was very close to the in vitro value.