Potassium advances circadian activity rhythms: interactions with lithium

Lithium delays the circadian rhythm of wheel-running in Syrian hamsters at plasma concentrations (0.59-0.74 mM) that also cause toxic weight loss. A moderate elevation of dietary potassium (up to 6 times normal intake) prevented lithium-induced weight loss in a dose-dependent manner, but had no effect on the delay of activity rhythms caused by lithium. Without lithium, the highest level of potassium intake advanced activity rhythms by 1 h relative to an entraining light:dark cycle. These results suggest that lithium's toxic, but not behavioral, actions involve an interaction with potassium ion. Furthermore, dietary potassium supplementation might have independent uses as treatment for chronobiological disorders.