Identification of an ATP-sensitive K+ channel in spiny neurons of rat caudate nucleus.

On the somata of GABAergic spiny neurons in the caudate nucleus of the rat an ATP-sensitive K+ channel (KATP-channel) was identified. The KATP-currents in cell-attached patches were activated both by energy-depleting conditions (200 microM cyanide) and by diazoxide (300 microM) and were reversibly blocked by tolbutamide (EC50 = 5 microM). In inside-out patch membranes both ATP (1 mM) and its non-hydrolyzable analog AMP-PNP (adenylylimidodiphosphate; EC50 = 27 microM) reversibly inhibited channel activity. These results demonstrate that the KATP-channel in spiny neurons displays properties characteristic of the KATP-channel in hippocampal, neocortical and nigral neurons and in pancreatic beta-cells.