Figure 4. NHE1- and NHE2-like, but not NHE3-like Na⁺-H⁺ exchange activity can be found in SMG duct cells.

BCECF-loaded SMG acini (A) and intralobular ducts (B) were used to measure the differential sensitivity of NHE activity to HOE 694 in the same recording field. After each cytosolic acidification by an NH₄⁺ pulse and Na⁺-free solution the cells were sequentially challenged with a Na⁺-containing solution in the presence of 0, 1.5 and 50 μMmu;m HOE. Note that 1.5 μMmu;m HOE nearly abolished NHE activity in acini and 50 μMmu;m HOE nearly abolished NHE activity in ducts.