Fig. 5. Current-voltage (I-V) relationships acquired from acidophilic Chlamydomonas sp. at pH 7 and pH 2. (A,B) Current recordings obtained at ±100 mV, acquired from the same acidophile at external pH 7 (A) and pH 2 (B). (C) Summary I-V plot from seven acidophiles normalized to cell surface area. The currents at pH 2 (open circles) are shifted to more negative potentials to correct for the change in glass charge during the change in extracellular pH. Inward currents are linearly proportional to the change in membrane potential and are greater at pH 2 (open circles) than at pH 7 (filled squares). Outward currents rise more rapidly with voltage than inward currents, as displayed by the difference between the plotted lines and the dotted lines representing a continuation of the slope of the inward currents. Values are means ± S.E.M.