Figure 2: Proton efflux via the MCT1 as subject to extracellular H+ and lactate. A MCT1-expressing oocyte was loaded with 3 mM lactate at pHo 7.0. After equilibrium was reached extracellular solution was either changed to 0 mM lactate, pHo 9.0 (A), 60 mM lactate, pHo 9.0 (B) or 0 mM lactate, pHo 6.0 (C). Shown is the intracellular H+ concentration shortly before and during change in extracellular solution. The sketches under the original recordings show the intra- and extracellular concentration of lactate and H+ at the point of change in extracellular solution.