Lack of evidence for coupling of the dopamine D2 receptor to an adenosine triphosphate-sensitive potassium (ATP-K+) channel in dopaminergic neurones of the rat substantia nigra.

Whole-cell patch clamp recordings were made from neurones in slices of rat substantia nigra zona compacta. The majority exhibited electrophysiological characteristics seen previously with intracellular recordings and were hyperpolarised by dopamine in a sulpiride-reversible manner. The sulphonylureas, tolbutamide and glibenclamide, did not reverse the response to dopamine and had no effect when applied alone. The potassium channel opener, cromakalim, was also without effect on dopaminergic neurones. Under our recording conditions, the potassium conductance activated by dopamine acting through the D2 receptor does not show the pharmacological characteristics of an ATP-sensitive potassium conductance.