ATP-sensitive potassium channels are regulated by dopamine D-2 receptors in the rat caudate-putamen

In earlier studies ATP-sensitive potassium (K-ATP(+)) channels that interact with neurotransmitter release in vitro were found in the rat caudate-putamen. In order to prove the dopamine (DA) receptor-mediated regulation of these channels, slices of rat caudate-putamen were incubated with the indicated substances in static chambers and the resulting catecholamine release was measured by HPLC with electrochemical detection. Butanedione monoxime (BUT), a specific K-ATP(+) channel blocker, concentration-dependently enhanced extracellular DA levels. Addition of the D-2 receptor agonist quinpirole (QUI) to the incubation medium, almost completely blocked BUT-induced DA outflow. Furthermore the D-2 receptor antagonist (-)-sulpiride (SLP) significantly induced DA release. SLP-induced enhancement was completely antagonized by coincubation with the K-ATP(+) channel opener diazoxide (DIA) in a concentration-dependent manner. These data led us to suggest that presynaptic D-2 receptors modulate striatal DA release through K-ATP(+) channels.