Figure 2.

Kinetic derivation of [Ca²⁺]_cyto(t) from fluorescence changes A, line scan images of fluorescence of fluo-4 or rhod-2, recorded simultaneously on the same cell, upon depolarization for 50 ms to +20 mV. B, fluorescence averages after normalization by the resting value (as described in Methods). Note that the relative increase by the end of the pulse is the same for both dyes, indicating that both are far from saturation by Ca²⁺. C, [Ca²⁺]_cyto(t) derived from records in B according to eqn (1), with k⁻_fluo-3= 90 s⁻¹ and k⁻_rhod-2= 100 s⁻¹. See further description in text and discussion in Appendix. Experiment 042408a, record 17.