The Ca(2+)-dependent activation by fluoride of human red cell membrane sodium permeability: evidence for a chemically activated tetrodotoxin-sensitive Na+ channel.
Fluoride (NaF) (5-15 mM) activated the 22Na+ uptake by human red blood cells (RBC). The effect was Ca(2+)-dependent. Sr2+, but not Ba2+, Mg2+, Mn2+, substituted Ca2+ in supporting the 22Na+ uptake. The NaF-induced 22Na+ uptake was sensitive to tetrodotoxin (TTX), pertussis toxin but not to amiloride nor valinomycin. The value of the influx was 8.6 +/- 5.0 mmol/l cells. Thus, the TTX-sensitive Na(+)-transport system is present in the RBC membrane in an inactive form which could be activated with NaF by a mechanism involving G-protein(s) but not the depolarization.
Department of Microbiology, Biochemistry and Biology, Slovak Technical University, Bratislava, Slovakia.
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Varecka
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Peterajová
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Sevcík
D002118:Calcium / Q000378:metabolism*; D002463:Cell Membrane Permeability / Q000187:drug effects; D004910:Erythrocyte Membrane / Q000187:drug effects* / Q000378:metabolism*; D005260:Female; D019204:GTP-Binding Proteins / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D017136:Ion Transport / Q000187:drug effects; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D037342:Pertussis Toxin; D012964:Sodium / Q000378:metabolism*; D015222:Sodium Channels / Q000187:drug effects / Q000378:metabolism; D012969:Sodium Fluoride / Q000494:pharmacology*; D013779:Tetrodotoxin / Q000494:pharmacology; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D015222:Sodium Channels; D010566:Virulence Factors, Bordetella; D013779:Tetrodotoxin; D012969:Sodium Fluoride; D012964:Sodium; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins; D002118:Calcium