Effect of probenecid on rat brain phenolsulfotransferase activity using dopamine as substrate

Dopamine sulfate (DAS) is formed by the action of phenolsulfotransferase (PST) on dopamine (DA). Since probenecid is often used to investigate the transport of monoamine acidic metabolites such as DAS from the brain, we investigated the effect of probenecid on rat brain PST activity utilizing DA as substrate. In the presence of 30 or 90 microM DA, probenecid had either no effect or a dose-related inhibitory effect on PST activity. PST activity increased at low probenecid concentrations, but decreased at high probenecid concentrations when 360 microM DA was utilized. Several conditions were found where PST activity was not affected by probenecid.