Fig. 1. Dopamine (DA)-induced changes in pH_i in duct cells of isolated salivary glands as measured with BCECF (A,B) and a double-barrelled pH-sensitive microelectrode (C). (A) Treatments with 1 µmol l^–1 and 100 nmol l^–1 DA induce a reversible intracellular acidification, N=5. (B) Dose–response relationship of the DA-induced intracellular acidification. Experiments were performed as in A and responses were normalised to the pH_i drop induced by a first 1 µmol l^–1 DA control stimulus (=100%). Values are means ± s.e.m. from 4–7 experiments for each concentration. A non-linear regression according to the Hill equation was fitted through the data points. (C) Effect of DA on pH_i (solid line) and basolateral membrane potential (PD_b, broken line). This recording, with a double-barrelled pH-sensitive microelectrode, is representative of five independent experiments.