Lithium lowers renal, cardiac and splenic ornithine decarboxylase activity in mice.

A single i.p. injection of lithium chloride (5-7.5 mumoles/g b.wt) in mice caused a 70-80% decrease in renal, cardiac and splenic ornithine decarboxylase (ODC) activity within 1 h, whereas pulmonary ODC activity was unaffected. Lithium chloride did not have any effect on ODC activity in vitro when added to homogenates of the tissues studied. We suggest that the effect of lithium on ODC activity is not direct, but mediated via e.g. hormonal or nervous influence.