Figure 2From: A novel delta current method for transport stoichiometry estimation HCO 3 − -induced current in NBCe2-C expressing HEK-293 cells. a) The cell was whole-cell voltage-clamped at -60 mV. A series of 400 ms voltage-clamp pulses range from -95 to +45 mV with increment of 10 mV were applied and whole-cell current responses were recorded. In the pre-HCO3 − conditions, there is no HCO3 − in the patch pipette (Table 1, patch solution a) nor in the bath solution (Table 1, Bath solution A). Increasing HCO3 − concentration to 25 mM in the bath solution (Bath solution B in Table 1) induced a voltage-dependent current (central panel). The current recovered when the cell was washed with solution containing 0 HCO3 − (right panel). b) Current-voltage (I-V) relation of steady-state current in the absence and presence of HCO3 − (n = 8). Im (pA): membrane current in pA. Steady-state current was obtained by averaging 80 ms of the current trace toward the end of each 400 ms voltage pulse. c) I-V curve of HCO3 − induced current is the difference between the I-V curves in the absence of HCO3 − and in the presence of HCO3 −. d) Application of 25 mM HCO3 − in the bath did not induce any current in EGFP negative cells (n = 4).Back to article page