Single cells were visualized by phase contrast microscopy and voltage-clamped using the whole cell patch clamp technique. Patch clamp micropipettes were obtained by pulling glass capillaries (1BBL W/FIL, OD 1.5 mm, World Precision Instruments, USA) with a model P-97 horizontal puller (Sutter Instrument Co., USA); when necessary, the micropipettes where polished by a model MF-830 microforge (Narishige, Japan). The resistance of the glass pipettes was 3–8 MΩ when filled with the pipette solution (for use with the hypertonic and hypotonic bath solutions the pipette solution was, in mM: CsCl 125, MgCl2 5, EGTA 11, raffinose 50, ATP 2, HEPES

Imatinib in vitro 10, 330 mOsm/kg, pH 7.2 (adjusted with CsOH); for use with the isotonic MAPK Inhibitor Library ic50 bath solution the pipette solution was, in mM: CsCl 125, MgCl2 5, EGTA 11,

raffinose 20, ATP 2, HEPES 10, 308 mOsm/kg, pH 7.2 (adjusted with CsOH)). The hypertonic bath solution was composed of (in mM): NaCl 125, CaCl2 2.5, MgCl2 2.5, HEPES 10, mannitol 100, 360 mOsm/kg, pH 7.4 (adjusted with NaOH). The isotonic bath solution was composed of (in mM): NaCl 125, CaCl2 2.5, MgCl2 2.5, HEPES 10, 308 mOsm/kg, pH 7.4 (osmolarity and pH adjusted with mannitol and NaOH, respectively). Fast exchange of the hypertonic bath solution with a hypotonic bath solution (in mM: NaCl 125, CaCl2 2.5, MgCl2 2.5, HEPES 10, 260 mOsm/kg, pH 7.4) was obtained using a perfusion system with a flow rate of 5 ml/min and a bath volume of ∼300 μl. For the experiments where the intracellular effect of curcumin was tested, 50 μM curcumin was added to the pipette filling (intracellular) solution. For the control experiments, an adequate volume of dimethyl sulfoxide (DMSO) as the vehicle was added to the pipette filling solution;

the final concentration of DMSO was 0.5%. Sitaxentan For the experiments where the extracellular, short-term effect of curcumin was tested, curcumin was added to the extracellular hypotonic (10 or 50 μM) or isotonic (10 μM) solution; for control experiments, an adequate volume of DMSO was added to the extracellular hypotonic or isotonic solution; the final concentration of DMSO was 0.1% or 0.5% for 10 or 50 μM curcumin, respectively. NPPB (Sigma, Austria) was used to discriminate between chloride currents and leakage currents. For the experiments where the extracellular, long-term effect of curcumin was tested, curcumin was added to the cell culture medium 1 h after seeding to the final concentrations of 0.1, 0.5, 1.0, 5.0 or 10 μM. For the control experiments, an adequate volume of DMSO as the vehicle was added to the medium of the cells; the final concentration of DMSO was 0.05%. Electrophysiology measurements were performed 16–24 h after cell seeding. All patch clamp experiments were carried out at room temperature.