Dose–response curve for the effects of pHi on channel activity. Experiments were performed on cell-excised inside-out membrane patches under symmetrical NMDG-Cl conditions, at Vm 80 mV. Pipette solution contained 5 mM Ca2+ (pHo 7.4), and the bath solution was calcium free. (A) Current traces from the same patch exposed to pHi 7.0–8.2. For clarity, the traces were superimposed, the dashed line indicating the closed channel current level (C-). The respective N′Po values are given on the right side of each trace. (B) Dose–response relationship. Each N′Po value at a given pHi was normalized to the paired N′Po at pHi 7.8 on the same patch. Data are means of measurements from four to five patches, and SEM is given as error bars when larger than symbols.
