Fig. 4.
SK-CO15 cells show robust NHE3 activity. A: Na+-dependent intracellular pH (pHi) recovery was measured to determine the rate of Na+/H+ exchange in SK-CO15 (SK) cells. HOE694 was used to selectively inhibit NHE1 (1 μM) or NHE1 and 2 (or 50 μM). The 10 μM S3226 was used to inhibit NHE3. Results are presented as means ± SE (n = 9). Con, control; H, HOE694; S, S3226. B: representative traces of Na+-dependent intracellular pH recovery in SK-CO15 cells are shown. C: NHE3 activities in SK-CO15, Caco-2, and C2b/NHE3V cells were compared. Results are presented as means ± SE (n = 9). D: representative traces of Na+-dependent pH recovery in SK-CO15 cells and Caco-2 cells in the presence of 50 μM HOE694 are shown. The rates of pHi recovery were much more consistent in SK-CO15 compared with Caco-2 cells.