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Figure 6 | BMC Biophysics

Figure 6

From: A novel delta current method for transport stoichiometry estimation

Figure 6

Computational simulation of membrane currents and reversal potentials. Addition of a Cl conductance (GCl) has a significant impact on ΔErev and therefore biases the estimation of q of NBC. Based on Eq. 2, currents were calculated with the same conditions as our whole-cell patch-clamp experiments for estimation of q of NBCe2-C and NBCe1-A: [HCO3 ]i = [HCO3 ]o = 25, [Na+]i =10 mM assuming q = 2 (panels a, b and c) or q = 3 (panels d, e and f). a) I-V curves when bath solution switched from [Na+]o =10 mM to 25 mM and the delta current (ΔI, the dark gray line). b) I-V curves when a relatively small GCl was present (light gray line) and the bath solution switched from [Na+]o =10 mM to 25 mM. C) I-V curves when a relatively larger Cl conductance (2 x GCl) was present (light gray line) and with the same bath solution switch as b). (d), (e) and (f) show the same operations as (a), (b) and (c) respectively except assuming q = 3. The insets in panel (d), (e) and (f) illustrate VI=0 by enlarging the local areas around I = 0. Y-axis’s are membrane currents of arbitrary unit for comparison purposes.

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