Figure 9. Cytosolic pH of HepG2 cells and generation of lactate.

(A) Cytosolic pH of HepG2 cells after their transfer from HBSS medium at pH 7.3 to the same medium (squares) or to HBSS buffered at pH 6.5 (circles). The values of cytosolic pH were determined using the fluorescent probe BCECF (see ‘Materials and methods’ section and Supplementary Figure S3). Experiments were performed in duplicate (empty and filled symbols). (B) Concentration of the lactate released by cells after 3 h of residence in HBSS medium at pH 7.3 or 6.5. Lactate was determined with a colorimetric (blue bars) or with an enzymatic (green bars) analytical procedure, using two independent samples for each determination. Error bars represent the standard deviation (n=2).