Figure 6. The time course of Ca_t, estimated from the I_NCX tail current.

Estimation of free Ca²⁺ in T-space,, using experimentally measured (top) and model generated (bottom) I_NCX and Ca_m, generated by V pulses as shown in the inset. A, I_NCX tail current traces. Raw current traces were truncated before the voltage was returned to the holding potential. Simulated traces, corresponding to the first and last V pulses, are shown in continuous and dashed black lines, respectively. B, corresponding optically measured (top) or model simulated (bottom) Ca_m. Circles in panels A and B indicate peaks of I_NCX tail currents and corresponding Ca_m values. Arrows in A and B indicate peak I_NCX and Ca_m, respectively. C, estimated Ca_t, , using eqn (12) with I_NCX from A and Ca_m from B as input. For the model-generated data (bottom panel), the actual model computed Ca_t is shown (grey traces) together with the estimated (circles).