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First published online March 31, 2007
Journal of Experimental Biology 210, 1463-1471 (2007)
Published by The Company of Biologists 2007
doi: 10.1242/jeb.001529

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A vacuolar-type H⁺-ATPase and a Na⁺/H⁺ exchanger contribute to intracellular pH regulation in cockroach salivary ducts

Carsten Hille^* and Bernd Walz

University of Potsdam, Institute of Biochemistry and Biology, Department of Animal Physiology, Karl-Liebknecht-Strasse 24-25, 14476 Potsdam-Golm, Germany

View larger version (16K): [in this window] [in a new window]   Fig. 1. Dopamine (DA)-induced changes in pHi 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 pHi 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 pHi (solid line) and basolateral membrane potential (PDb, broken line). This recording, with a double-barrelled pH-sensitive microelectrode, is representative of five independent experiments.

View larger version (20K): [in this window] [in a new window]   Fig. 2. Recordings of the effects of 1 µmol l–1 concanamycin A (A), Na+-free (0Na+) physiological saline (PS; B) and the combined application of concanamycin A (ConA) and Na+-free PS (C) on pH changes induced by 1 µmol l–1 dopamine (DA). (D) Quantitative analysis of the rates of pHi recovery in the above experiments and in an experiment in which 1 µmol l–1 ConA and 50 µmol l–1 EIPA were applied simultaneously. Values are means ± s.e.m.; the number of experiments is given under each bar; one-way ANOVA, *P<0.05, **P<0.01.

View larger version (27K): [in this window] [in a new window]   Fig. 3. Recordings of the effects of (A) 1 µmol l–1 concanamycin A (ConA), (B) Na+-free physiological saline (PS), (C) 1 µmol l–1 ConA in Na+-free PS (D) and 50 µmol l–1 EIPA together with 1 µmol l–1 ConA, on pH changes induced by a brief application of 20 mmol l–1 NH4Cl to isolated salivary ducts. (E) Quantitative analysis of the rates of pHi recovery in the above experiments. Values are means ± s.e.m.; the number of experiments is given under each bar; one-way ANOVA, *P<0.05, **P<0.01.