Fig. 1. Swelling activated Cl^- currents (I_Cl,swell) in BV-2 microglial cells. (A) Representative current-voltage relationship obtained by 500 ms voltage ramps under isotonic and hypotonic conditions in the absence and presence of the Cl^- channel blocker DCPIB (10 µM). Note that the voltage ramp tracings under isotonic- and hypotonic/DCPIB conditions are superimposed. (B) Representative current traces elicited by 500 ms voltage-steps during the superfusion with isotonic- (upper trace) and hypotonic bath solution in the absence (middle trace) and presence (lower trace) of 10 µM DCPIP. (C) Mean peak currents under isotonic- and hypotonic conditions in the absence and presence of 10 µM DCPIB (n=3; asterisks indicate significant differences to hypotonic). (D) Determination of reversal potentials using ruptured whole-cell patch clamp under symmetric intra- and extracellular Cl^- concentrations and upon equimolar extracellular substitution of NaCl (Cl^-) with NaI (I^-) and Na-gluconate (gluc^-). The anion replacements lead to shifts of the reversal potential to negative- (I^-) and positive (gluc^-) values, respectively. Overlay of three representative original tracings. (E) Relative anion permeability (P_X/P_Cl^-) for I^- and gluc^- ions with respect to Cl^- as calculated from the shift of the respective reversal potentials as shown in D. Asterisks indicate significant differences to the anion permeability for Cl^- (n=3-4). Means±SEM; * p<0.05, ** p<0.01.