Activated phagocytes undergo a massive burst of metabolic acid generation, yet must be able to maintain their cytosolic pH (pHi) within physiological limits. Peroxides of vanadate (V(4+)-OOH), potent inhibitors of phosphotyrosine phosphatases, have recently been shown to produce activation of the respiratory burst in HL60 granulocytes. We therefore investigated the effects of V(4+)-OOH on pHi homoeostasis in HL60 granulocytes, using a pH-sensitive fluorescent dye. V(4+)-OOH stimulation induced a biphasic pH change: a transient cytosolic acidification followed by a significant alkalinization. The initial acidification was prevented by inhibition of the NADPH oxidase and was absent in undifferentiated cells lacking oxidase activity. Analysis of the alkalinization phase demonstrated the involvement of the Na+/H+ antiporter, and also provided evidence for activation of two alternative H(+)-extrusion pathways: a bafilomycin-sensitive component, likely reflecting vacuolar-type H(+)-ATPase activity, and a Zn(2+)-sensitive H(+)-conductive pathway. Our results indicate that V(4+)-OOH stimulation not only activated the NADPH oxidase but concomitantly stimulated H(+)-extrusion pathways, enabling the cells to compensate for the massive production of intracellular H+ associated with the respiratory burst.
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July 1994
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Research Article|
July 15 1994
Activation of multiple pH-regulatory pathways in granulocytes by a phosphotyrosine phosphatase antagonist
L Bianchini;
L Bianchini
1Division of Cell Biology, Hospital for Sick Children, 555 University Avenue, Toronto, Ont. M5G 1X8, Canada
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A Nanda;
A Nanda
1Division of Cell Biology, Hospital for Sick Children, 555 University Avenue, Toronto, Ont. M5G 1X8, Canada
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S Wasan;
S Wasan
1Division of Cell Biology, Hospital for Sick Children, 555 University Avenue, Toronto, Ont. M5G 1X8, Canada
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S Grinstein
S Grinstein
1Division of Cell Biology, Hospital for Sick Children, 555 University Avenue, Toronto, Ont. M5G 1X8, Canada
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Publisher: Portland Press Ltd
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© 1994 The Biochemical Society, London
1994
Biochem J (1994) 301 (2): 539–544.
Citation
L Bianchini, A Nanda, S Wasan, S Grinstein; Activation of multiple pH-regulatory pathways in granulocytes by a phosphotyrosine phosphatase antagonist. Biochem J 15 July 1994; 301 (2): 539–544. doi: https://doi.org/10.1042/bj3010539
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