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Figure 3 | BMC Biophysics

Figure 3

From: A novel delta current method for transport stoichiometry estimation

Figure 3

Estimation of transport stoichiometry for NBCe2-C using conventional reversal potential method. a) In the conditions of equal concentrations (25 mM) of HCO3 intra- and extracellularly, the ratio of intracellular concentration of Na+ ([Na+]i) and extracellular concentration of Na+ ([Na+]o) = 40/80 mM (Patch solution d/bath solution C in Table 1), cells were voltage-clamped at -60 mV. Current responses to a series of 400 mV voltage pulses from -95 to +45 mV with increment of 10 mV were recorded in the absence (pre-DIDS Control, Ctrl) and presence of DIDS (0.5 mM). DIDS sensitive current (right panel, Ctrl-DIDS) was obtained by digital subtraction of currents in the presence of DIDS (center panel) from control current (n = 3). B) I-V relations of steady-state current in Ctrl, DIDS and Ctrl-DIDS conditions. c) I-V curves obtained with the same protocol as (b) except [Na+]i/[Na+]o = 25/135 mM (Patch solution c/bath solution B in Table 1) (n = 5). d) The two VI=0 values are close to the calculated values assuming q = 2 (dash lines) while significantly distinct from the calculated values assuming q = 3 (dash lines).

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