Title: Tetradotoxin-sensitive and tetrodotoxin-resistant Na+ channels differ in their sensitivity to Cd2+ and Zn2+
Abstract: The sensitivity of Na+ channels to inhibition by Cd2+ and Zn2+ was studied in 22Na+ uptake experiments after stabilization of an open conformation of the Na+ channels with different neutoxins and in voltage clamp experiments. Six different cell types of neuronal, cardiac or skeletal muscle origin were surveyed. Three cell types posses Na+ channels that are highly sensitive to tetrodotoxin (TTX) (Kd = 1−5 nM) and three possess Na+ channels that are resistant to TTX (Kd = 0.3−1 μM). The 22Na+ uptake experiments using veratridine or batrachotoxin to (IC50(Cd2+) = 0.2 mM) and of Zn2+ (IC50(Zn2+) = 50 μM) than TTX-sensitive Na+ channels (IC50(Cd2+) = 5 mM, (IC50(Zn2+) = 2 mM) Electrophysiological experiments showed that high concentrations of Cd2+ (IC50 = 2 mM) are necessary to inhibit both TTX-sensitive and TTX-insensitive Na+ channels when the channels are activated by voltage steps. The results suggest that Cd2+ acts comptetively with veratridine or batrachotoxin and that the difference in the effects of Cd2+ and Zn2+ on 22Na+ fluxes in TTX-sensitive and TTX-resistant cells is related to differences at the site of action of alkaloid neurotoxins.
Publication Year: 1986
Publication Date: 1986-03-01
Language: en
Type: article
Indexed In: ['crossref', 'pubmed']
Access and Citation
Cited By Count: 88
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