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 μM cyanide) and by diazoxide (300 μM) and were reversibly blocked by tolbutamide (EC50=5 μM). In inside-out patch membranes both ATP (1 mM) and its non-hydrolyzable analog AMP-PNP (adenylylimidodiphosphate; EC50=27μM) 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 s-cells.