Figure. 3.

DAMGO-induced currents in wild-type and GIRK knock-out lamina II neurons. Whole-cell currents were measured at a holding potential of −60 mV. A, Typical profile of an outward current evoked by 3 μm DAMGO, and its subsequent reversal by naloxone (10 μm), seen in a lamina II neuron from a wild-type mouse. Currents were accompanied by corresponding decreases in membrane resistance (data not shown). B, The concentration–response relationship between DAMGO and evoked currents in wild-type lamina II neurons (F_(3,33)= 5.0; p < 0.01). At each concentration, data from 7–12 responding cells were used to compile an average. *p < 0.05 versus 0.01 μm DAMGO. C, Effect of GIRK subunit ablation on peak current evoked by 3 μm DAMGO. A significant impact of genotype was observed (F_(3,29)= 4.2; p < 0.05), with DAMGO-induced currents blunted in lamina II neurons from GIRK2 knock-out mice (G2; n= 4). DAMGO-induced currents were also reduced in the responding neurons from GIRK1 knock-out mice (G1; n= 5) but not from GIRK3 knock-out mice (G3; n= 12).*p < 0.05 versus wild type (WT). Error bars indicate SEM.