Figure 2.

Lactate permeability of the plasma membrane of normal and P. falciparum–infected red blood cells. (A) Current traces of a noninfected erythrocyte recorded with NMDG-Cl pipette solution and NaCl or Na-l-lactate bath solution. Currents were obtained in fast whole-cell voltage-clamp mode. The membrane potential was held at −30 mV and currents were elicited by 400-ms square pulses to test potentials between −100 and +100 mV; zero current is indicated by dashed line. (B) Mean current-voltage (I-V) relations (±SE, n = 4–8) of noninfected erythrocytes recorded as in A with NaCl- (circles) or Na-l-lactate bath solution (triangles). Current values were analyzed between 350 and 375 ms of each square pulses. (C) Current traces of two infected cells recorded with NMDG-Cl (top line) or Na-l-lactate pipette solution (bottom line). Currents were measured in NaCl bath solution, after substitution of bath NaCl with Na-l-lactate and Na-gluconate, and after wash-out of Na-gluconate by NaCl. (D and E) Mean I-V relations (±SE) recorded as in C with NMDG-Cl (D, n = 6–8) and Na-lactate pipette solution (E, n = 5–8) combined with NaCl- (circles), Na-l-lactate (triangles), or Na-gluconate bath solution (squares). (F) Current traces recorded with NMDG-Cl pipette solution and NaCl or Na-d-lactate bath solution. (G) Mean shift in reversal potential (±SE) induced by replacement of NaCl by equimolar quantities of -l- or -d-lactate in the bath solution (n = 4–8).