Functional polymorphisms in PSAC gating. (A) Three-channel patches from 7G8- and Indo 1–infected cells, left and right sweeps respectively. (B) Single-channel recordings. The scale bars represent 4 pA/400 ms in panel A and 3 pA/525 ms in panel B. Identical V_m values were imposed for each isolate, as indicated. Dashed red and dotted green lines represent closed and open channel levels, respectively. PSAC behavior in these isolates differed at a V_m of +100 mV with more frequent openings (brief upward spikes in upper traces) on Indo 1 than on 7G8. To avoid bias, these traces were selected because they have open probabilities matching the average for their corresponding isolates (10 single-channel patches each). (C) Whole-cell current-voltage profiles for single RBCs infected with either an Indo 1 parasite (○) or a 7G8 parasite (▾). Red lines illustrate the differing chord conductances between +50 mV and +100 mV. For each isolate, similar results were obtained using blood from approximately 9 separate donors.