Norepinephrine metabolism in mouse heart after lithium and rubidium treatment

This report describes the effects of treatment with lithium (Li), rubidium (Rb) and sodium (Na; 1 mEq/kg/day) for 7 days on norepinephrine (NE) turnover in mouse heart. The effects of several drugs which modify the uptake and storage of NE were also studied in similarly pretreated mice. A method based on the combustion of tissue tritium to tritiated water was used to assay tritiated l-norepinephrine (l-NE-3H) concentrations in individual hearts. The rate of decline of tissue tritium concentrations in groups of pretreated mice maintained at ambient temperature (23--24 degrees C) or in the cold (4--5 degrees C) was determined. The results indicate that, compared to Na, Li and Rb did not modify the tritium turnover rate in mouse heart. Pretreatment with Li or Rb did not modify the uptake of tritiated NE in the heart. The effects of desipramine. cocaine, bretylium and chlorpromazine on NE uptake were not altered by the alkali ions. Further, pretreatment did not modify NE release by tyramine, metaraminol and guanethidine. These studies suggest that Li and Rb do not modify NE uptake, release and storage in mouse heart.