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Figure 5 | BMC Biophysics

Figure 5

From: A novel delta current method for transport stoichiometry estimation

Figure 5

Estimation of transport stoichiometry for NBCe1-A using the delta current method. a) NBCe1-A expressing cells were voltage clamped at -50 mV. A series of 400 ms voltage-clamp pulses range from -108 to +48 mV with increment of 12 mV (containing a pulse to 0 mV during this protocol) was applied and whole-cell current responses were recorded. Patch pipette solution contained 10 mM Na+ and 25 mM HCO3 (Solution b in Table 1). Bath solution also contained 10 mM Na+ and 25 mM HCO3 (Bath solution D in Table 1) (left panel). Enhancing Na+ concentration from 10 to 25 mM in the bath solution (Bath solution E in Table 1). increased voltage-dependent current (central panel). Net current (ΔI) through NBCe1-A induced by changing [Na+]o was obtained by subtracting the current traces at [Na+]o = 10 mM from the current traces at [Na+]o = 25 mM (right panel). b) Current-voltage (I-V) relations of steady-state current (mean of 80 ms current trace toward the end of each voltage pulse) in bath solutions containing 10 mM and 25 mM Na+. c) I-V relation of ΔI. d) Estimation of transport stoichiometry ratio q with Eq. 7 (n = 6).

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