Indirect ultrastructural evidence for lithium uptake by cultured rat cerebral cells through the sodium channel

Cerebral cortices, prepared from 18-day-old rat embryos, were grown in explant cultures for 18 days. They were then incubated for 25 min in media of 3 types of cationic composition with and without tetrodotoxin and/or veratridine. Qualitative and quantitative ultrastructural observations revealed a considerable swelling of neuronal elements following veratridine exposure in both Na+ and Li+ media; this swelling was prevented by tetrodotoxin. By contrast, veratridine failed to induce swelling of neuronal profiles in a choline+ medium. The results indirectly indicate that Li+ ions enter cultured rat cerebral cells through the Na+ channels.