I-V relationships of MS channels with 145 mm NMDGCl in the pipette (cell-attached recording, filled squares), and in the cytosol-like bathing solution (inside-out recording, open circles). Single-current measurements were performed over a wide range of membrane potentials: at potentials up to −150 mV with NMDG in the pipette, no inward currents were observed; at potentials up to +60 mV with NMDG in the cytosol-like bathing solution, no outward currents were observed.