Potassium, rubidium, and 4-aminopyridine effects on the circadian running rhythm in the hamster

The period of the circadian rhythm of wheel-running was shortened when golden hamsters were given supplemental dietary potassium or rubidium for two weeks. Treatment with 4-aminopyridine, a potassium channel blocker, significantly increased circadian period. These period changes (0.17 h for potassium treatment, 0.14 h for rubidium, and 0.07 h for 4-aminopyridine) support previous data indicating that potassium is a component of the mammalian biological clock mechanism.