Effect of RbCl on the circadian rhythm of locomotor activity in the cockroachLeucophaea maderae

Abstract
The period length of the running wheel activity rhythm of cockroaches (Leucophaea maderae), which is lengthened by Li+, was found to be shortened by 0.7% by administering 50 mM RbCl in the drinking water. Replacing the Rb+ solution by H2O for four weeks did not bring the period length back to the control value. This is probably due to the long biological half life of Rb+ in the cells. The phenomenon is another instance in which the effect of Rb+ is opposite to that of Li+.