Lithium transport in human fibroblasts: Relationship to RBC lithium transport and psychiatric diagnoses

Cultured fibroblasts were prepared from six normal controls, five DSM-III manic patients, and six DSM-III schizophrenic patients. Lithium (Li⁺) uptake, 24-hour Li⁺ ratios, and steady-state membrane potential were measured in these cell lines. The uptake of 10 mM Li⁺ reached maximum at 2 hours with an intracellular concentration of approximately 15 mM. No significant difference in uptake was found among subject groups. Twenty-four hour Li⁺ (ratio of intracellular/extracellular Li⁺) ratios were determined by incubating the cell lines for 24 hours in the presence of 2 mM Li⁺. No significant difference was observed among groups; nor was there any significant correlation between the fibroblast 24-hour ratios and 24-hour in vitro ratios determined in donor red cells. The relationship between membrane potential and the 24 hour Li⁺ ratio in fibroblasts was determined. The average potential in these cell lines was -56 mV and was not affected by Li⁺ treatment. No correlation between the Li⁺ ratio and membrane potential was found.