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Vanadate and fluoride activate red cell Na+ permeability by different mechanism
L Varecka1, E Peterajová, E Písová
1Department of Microbiology, Biochemistry and Biology, Slovak Technical University, Bratislava.
General Physiology and Biophysics
|April 1, 1994
Summary
Fluoride and vanadate induce calcium-dependent sodium influx in red blood cells. Vanadate activates the Na/H antiporter, while fluoride opens a tetrodotoxin-sensitive sodium channel.
Area of Science:
- Cell Physiology
- Ion Transport Mechanisms
- Red Blood Cell Biology
Background:
- Fluoride and vanadate are established inducers of calcium-dependent potassium efflux.
- The impact of these agents on sodium influx in red blood cells remains less understood.
Purpose of the Study:
- To investigate the effects of fluoride and vanadate on calcium-dependent sodium (Na+) influx in red blood cells.
- To elucidate the specific ion transport pathways involved in these responses.
Main Methods:
- Utilizing radioactive sodium-22 (22Na+) to measure Na+ influx in red blood cells.
- Employing pharmacological inhibitors like amiloride and tetrodotoxin to differentiate ion channel activity.
Main Results:
- Both fluoride and vanadate induced Ca(2+)-dependent 22Na+ influx in red blood cells.
- Vanadate-induced Na+ influx was observed in guinea-pig but not human red blood cells, and was amiloride-sensitive.
- Fluoride-induced Na+ influx was observed in human red blood cells and was tetrodotoxin-sensitive.
- These findings suggest vanadate activates the Na/H antiporter and fluoride opens a tetrodotoxin-sensitive Na+ channel.
Conclusions:
- Vanadate and fluoride differentially modulate Ca(2+)-dependent Na+ permeability in red blood cells.
- Vanadate utilizes the Na/H antiporter, while fluoride employs a tetrodotoxin-sensitive Na+ channel.
- Both agents likely involve additional auxiliary mechanisms to activate Ca(2+)-dependent Na+ permeabilities.