THE EFFECT OF OUABAIN ON CATECHOLAMINE BIOSYNTHESIS IN RAT BRAIN CORTEX SLICES

¹ New York University School of Medicine, Department of Psychiatry and Neurology, Neurochemistry Laboratory, New York, New York

The net uptake of C¹⁴-tyrosine and the formation of C¹⁴-catecholamines from C¹⁴-tyrosine was studied in rat brain cortex slices in presence and absence of ouabain. The net uptake of C¹⁴-tyrosine was decreased by lowering the incubation temperature, by incubation in air instead of oxygen, by deprivation of glucose and by addition of ouabain. Ouabain enhances the C¹⁴-catecholamine formation from C¹⁴-tyrosine. The increase effected by ouabain is evident by the increase in the C¹⁴-dopamine concentration in the medium and by the increase in C¹⁴-norepinephrine in the slices. The latter increase is only evident upon short incubation time periods. The impairment of the regulation of catecholamine biosynthesis by the feedback inhibition might be responsible for the ouabain induced acceleration in catecholamine biosynthesis.