Sulfonylurea-sensitive adenosine triphosphate (ATP)-regulated potassium (K_ATP) channels are present in brain cells and play a role in neurosecretion at nerve terminals. K_ATP channels in substantia nigra, a brain region that shows high sulfonylurea binding, are inactivated by high glucose concentrations and by antidiabetic sulfonylureas and are activated by ATP depletion and anoxia. K_ATP channel inhibition leads to activation of γ-aminobutyric acid (GABA) release, whereas K_ATP channel activation leads to inhibition of GABA release. These channels may be involved in the response of the brain to hyper- and hypoglycemia (in diabetes) and ischemia or anoxia.