Dependence of run-up and run-down on cell dialysis, Ca²⁺, and voltage. (A) Comparison of time-course recordings performed under standard recording conditions (Ctrl, with R_s = 6 ± 1 MΩ and C_s = 14 ± 1 pF; same data as in Fig. 1) or with high-resistance pipettes (R_s = 12 ± 1 MΩ) in large cells (C_s = 29 ± 6 pF) to retard cytosolic dilution (high C_s, n = 6). (B) Comparison of the run-up duration, determined as the time required for currents to reach their maximum amplitude (same cells as in A). (C) Comparison of the residual current after partial run-down, determined as the ratio between current amplitudes after 7 min of run-down and at time 0 (same cells as in A). (D) Comparison of the current increase during run-up, determined as the ratio between maximum and initial current amplitude (same cells as in A). (E) Comparison of time-course recordings performed with 5 mM Ba²⁺ (n = 5) or Ca²⁺ (n = 5) as the charge carrier. Dotted lines are extrapolated single exponential fits to the evolution of currents during run-up, which yielded the time-constant indicated above. (F) Comparison of the run-up duration observed with Ba²⁺ or Ca²⁺ as the charge carrier (same cells as in E). (G) Mean current traces evoked by a 50-ms voltage ramp from −80 mV to 60 mV immediately after establishing the whole-cell configuration (I_start, blue solid line), at the time of maximum I_Ba (I_max, black solid line) and after 7 min of run-down (I_7min, orange broken line; n = 7). Inset: Same current traces but scaled to their maximum value to illustrate the lack of changes in position and shape during run-up and subsequent left shift of the curve during run-down. **, P < 0.01; ***, P < 0.001 vs. Ctrl in B and C or vs. Ba²⁺ in F (one-way ANOVA with Bonferroni post-hoc correction). Values are expressed as mean ± SEM.