Comparison between extracellular and tissue fluctuation of dopamine and related metabolites in striatum under hypoxia

The time course of changes in both extracellular and tissue levels of dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) in the striatum of halothane-anesthetized rats was compared under hypoxic conditions. A 100-fold increase in the extracellular DA was observed within 20 min of hypoxia, while the tissue DA showed a 1.2-fold increase at the maximum. The inhibition of oxygen-dependent enzymes gives no satisfactory explanation for the acute DA increase, the disruption of DA uptake mechanisms may also participate in this.