QX-314 BLOCKS THE POTASSIUM BUT NOT THE SODIUM-DEPENDENT COMPONENT OF THE OPIATE RESPONSE IN LOCUS-CERULEUS NEURONS

Opiates hyperpolarize locus coeruleus neurons by simultaneously opening K+ channels and turning off a resting Na+-dependent inward current. Intracellularly applied QX-314 reduced the opiate current to approximately 40% of the control and the residual current did not reverse near E(K), suggesting lack of a significant K+ component. Replacement of Na+ virtually abolished the residual opiate response. Thus, QX-314 blocks the K+ but not the Na+-dependent component of the opiate-induced outward current in LC neurons.