TOLBUTAMIDE-SENSITIVE AND DIAZOXIDE-SENSITIVE K+ CHANNEL IN NEURONS OF SUBSTANTIA-NIGRA PARS-RETICULATA

Single-channel K+ currents were recorded in cell-attached patches from slices of rat substantia nigra. On the somata of neurons in the caudal half of the substantia nigra pars reticulata a K+ selective channel with a unitary conductance of 71 pS (154 mmol/l K + in pipette filling solution) was identified. The channel was activated both by application of diazoxide (300 mumol/l) and by energy-depleting conditions (200 mumol/l cyanide) and was reversibly blocked by tolbutamide (0.1 - 1 mmol/l). It is concluded that neurons in the substantia nigra pars reticulata of the rat contain a typical ATP-sensitive K+ channel the activity of which can be modulated by diazoxide and sulfonylureas.