TY  - JOUR
A1  - Schewe, Bettina
A1  - Blenau, Wolfgang
A1  - Walz, Bernd
T1  - Intracellular pH regulation in unstimulated Calliphora salivary glands is Na+ dependent and requires V-ATPase activity
JF  - The journal of experimental biology
N2  - 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 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.
KW  - Calliphora vicina
KW  - salivary gland
KW  - intracellular pH regulation
KW  - Na+/H+ antiporter
KW  - NHE
KW  - vacuolar H+-ATPase
KW  - V-ATPase
KW  - intracellular pH
KW  - insect
KW  - blowfly
KW  - BCECF
KW  - NH4Cl prepulse
Y1  - 2012
U6  - https://doi.org/10.1242/jeb.063172
SN  - 0022-0949
VL  - 215
IS  - 8
SP  - 1337
EP  - 1345
PB  - Company of Biologists Limited
CY  - Cambridge
ER  -