Extracellular dopamine in rat striatum following uptake inhibition by cocaine, nomifensine and benztropine.

A microdialysis/smallbore chromatographic system was used to monitor changes in extracellular dopamine concentration in the striatum of the rat following administration of drugs that block catecholamine uptake. Analysis of 0.5 microliter of dialysate every 5 min showed dose-dependent elevations in extracellular dopamine following systemic administration of nomifensine (1 and 10 mg/kg), benztropine (5 and 25 mg/kg) and cocaine (3, 10 and 30 mg/kg). The order of potency in vivo was nomifensine greater than cocaine greater than benztropine. The short sampling interval allows accurate temporal profiles following pharmacological manipulations to be acquired.