Lithium can be toxic in rodents and human patients at concentrations w
ithin the therapeutic range for treatment of affective disorders. Diet
containing supplemental potassium reduced lithium-induced weight loss
in hamsters following daily injections of 3 mmol LiCl/kg for 7-10 day
s. Potassium supplementation also decreased lithium concentrations in
peripheral tissues, but no in brain, after repeated lithium administra
tion. Repeated lithium injection lowered the concentration of potassiu
m in peripheral tissues, but tissue potassium was not restored by diet
ary potassium supplementation. Toxic effects of single injections of 1
-10 mmol LiCl/kg were unaffected by dietary potassium. Lithium concent
rations in plasma, brain, or peripheral tissues 6-hr after injection o
f 5 mmol LiCl/kg were also not altered by potassium diet. These data s
uggest that interactions between lithium and potassium diet differ in
peripheral tissues compared to the central nervous system, and after a
cute versus chronic lithium administration.