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Vanadate stimulates Na+/H+ exchange activity in A431 cells
Biochemical and Biophysical Research Communications
|January 30, 1984
Summary
Vanadate, a mitogen, activates sodium-hydrogen exchange (Na+/H+ exchange) in cultured cells, increasing cytoplasmic pH (pHi). This mechanism is similar to growth factors, suggesting a common pathway for mitogenic activation.
Area of Science:
- Cell biology
- Biochemistry
- Molecular signaling
Background:
- Polypeptide growth factors elevate cytoplasmic pH (pHi) in mammalian cells.
- This pHi elevation is mediated by stimulating sodium-hydrogen exchange (Na+/H+ exchange).
Purpose of the Study:
- To investigate the effect of vanadate, a known mitogen, on Na+/H+ exchange and pHi in cultured cells.
- To determine if vanadate activates Na+/H+ exchange through a mechanism similar to polypeptide growth factors.
Main Methods:
- Utilized A431 cells to study vanadate's effect on Na+/H+ exchange.
- Measured cytoplasmic pH (pHi) changes in response to vanadate and epidermal growth factor (EGF).
- Assessed the impact on the rate of pHi recovery after an acid load.
Main Results:
- Vanadate reversibly activated Na+/H+ exchange at micromolar concentrations, significantly increasing pHi.
- Vanadate's effect was independent of Na+/K+ ATPase inhibition and cAMP levels.
- Kinetics of pHi elevation by vanadate and EGF were similar.
- Both agents enhanced pHi recovery after acid loading.
Conclusions:
- Vanadate stimulates Na+/H+ exchange via a mechanism comparable to polypeptide growth factors like EGF.
- Activation of Na+/H+ exchange may be a shared property of diverse mitogens, not limited to growth factors.