A, representative traces showing the effect of acidosis on the current–voltage relationship of the csNSC channel. Currents were activated by lowering Ca2+ from 2.0 to 0.1 mM over a range of holding potentials from −60 to +20 mV, at normal (7.5, left panel) and low (6.5, right panel) pH. B, I–V curves of the csNSC channel at pH 7.5 and 6.5. Both I–V curves display a linear relationship with reversal potentials near 0 mV. A decrease in pH to 6.5 inhibits the amplitude of the csNSC currents at all potentials. C, summary data showing the voltage-independent inhibition of the csNSC currents by pH 6.5. The amplitudes of the csNSC currents at −60, −40, −20 and +20 mV were decreased by pH 6.5 to 68 ± 5 %, 66 ± 6 %, 59 ± 8 % and 67 ± 9 % of the control currents recorded at pH 7.5, n = 5, P > 0.05.