Intracellular pH regulation in unstimulated Calliphora salivary glands is Na+ dependent and requires V-ATPase activity
- Salivary gland cells of the blowfly Calliphora vicina have a vacuolar-type H+-ATPase (V-ATPase) that lies in their apical membrane and energizes the secretion of a KCl-rich primary saliva upon stimulation with serotonin (5-hydroxytryptamine). Whether and to what extent V-ATPase contributes to intracellular pH (pH(i)) regulation in unstimulated gland cells is unknown. We used the fluorescent dye BCECF to study intracellular pH(i) regulation microfluorometrically and show that: (1) under resting conditions, the application of Na+-free physiological saline induces an intracellular alkalinization attributable to the inhibition of the activity of a Na+-dependent glutamate transporter; (2) the maintenance of resting pHi is Na+, Cl-, concanamycin A and DIDS sensitive; (3) recovery from an intracellular acid load is Na+ sensitive and requires V-ATPase activity; (4) the Na+/H+ antiporter is not involved in pHi recovery after a NH4Cl prepulse; and (5) at least one Na+-dependent transporter and the V-ATPase maintain recovery from anSalivary gland cells of the blowfly Calliphora vicina have a vacuolar-type H+-ATPase (V-ATPase) that lies in their apical membrane and energizes the secretion of a KCl-rich primary saliva upon stimulation with serotonin (5-hydroxytryptamine). Whether and to what extent V-ATPase contributes to intracellular pH (pH(i)) regulation in unstimulated gland cells is unknown. We used the fluorescent dye BCECF to study intracellular pH(i) regulation microfluorometrically and show that: (1) under resting conditions, the application of Na+-free physiological saline induces an intracellular alkalinization attributable to the inhibition of the activity of a Na+-dependent glutamate transporter; (2) the maintenance of resting pHi is Na+, Cl-, concanamycin A and DIDS sensitive; (3) recovery from an intracellular acid load is Na+ sensitive and requires V-ATPase activity; (4) the Na+/H+ antiporter is not involved in pHi recovery after a NH4Cl prepulse; and (5) at least one Na+-dependent transporter and the V-ATPase maintain recovery from an intracellular acid load. Thus, under resting conditions, the V-ATPase and at least one Na+-dependent transporter maintain normal pH(i) values of pH.7.5. We have also detected the presence of a Na+-dependent glutamate transporter, which seems to act as an acid loader. Despite this not being a common pH(i)-regulating transporter, its activity affects steady-state pH(i) in C. vicina salivary gland cells.…
Author details: | Bettina Schewe, Wolfgang BlenauORCiDGND, Bernd Walz |
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DOI: | https://doi.org/10.1242/jeb.063172 |
ISSN: | 0022-0949 |
Title of parent work (English): | The journal of experimental biology |
Publisher: | Company of Biologists Limited |
Place of publishing: | Cambridge |
Publication type: | Article |
Language: | English |
Year of first publication: | 2012 |
Publication year: | 2012 |
Release date: | 2017/03/26 |
Tag: | BCECF; Calliphora vicina; NH4Cl prepulse; NHE; Na+/H+ antiporter; V-ATPase; blowfly; insect; intracellular pH; intracellular pH regulation; salivary gland; vacuolar H+-ATPase |
Volume: | 215 |
Issue: | 8 |
Number of pages: | 9 |
First page: | 1337 |
Last Page: | 1345 |
Funding institution: | Deutsche Forschungsgemeinschaft [Wa 463/9-5, Graduiertenkolleg 837 Functional Insect Science] |
Organizational units: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Biochemie und Biologie |
Peer review: | Referiert |