Dynamic Characteristics of the ‘Functional Compartment’ of Dopamine in Dopaminergic Terminals of the Rat Striatum

Rats were injected with α‐methyl‐ p ‐tyrosine and the disappearance of dopamine in the striatum was examined as a function of time. Two main phases of dopamine decline were detected which probably correspond to the amine utilization in a ‘functional’ and a ‘main storage compartment’ in dopaminergic terminals. Similar observations were made when the turnover of dopamine had been previously accelerated by thioproperazine. In control rats the half‐lives of dopamine were about 9 and 120 min in the ‘functional’ and ‘main storage’ compartments respectively. The rate of dopamine synthesis was estimated to be not less than 13‐2 μg/g/h and the rate of dopamine utilization in the ‘functional compartment’ was calculated to be about four times that of the ‘main storage compartment'.