Pharmacological and Electrophysiological Characterization of Lithium Ion Flux Through the Action Potential Sodium Channel in Neuroblastoma × Glioma Hybrid Cells

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Abstract
Interaction of Li+ with the voltage‐dependent Na+ channel has been analyzed in neuroblastoma × glioma hybrid cells. The cells were able to generate action potentials in media containing Li+ instead of Na+. The uptake of Li+ into the hybrid cells was investigated for the pharmacological analysis of Li+ permeation through voltage‐dependent Na+ channels. Veratridine and acionitine increased the uptake of Li+ to the same degree (EC50 30 μM). This increase was blocked by tetrodotoxin (IC50 20 nM). Veratridine and aconitine did not act synergistically; however, the veratridine‐stimulated influx was further enhanced by the toxin of the scorpion Leiurus quinquestriatus (EC50 0.06 μg/ml). This stimulation was also blocked by tetrodotoxin. Thus, the voltage‐dependent Na+ channel of the hybrid cells accepts both Li+ and Na+ in a similar manner.