Figure 3.

Inhibition of PTP enables inadequate stimulation to induce LTP-IE. Somatic current pulse injection for 2 s, which elicits a 50 Hz AP train, was used as an inadequate conditioning stimulation. For inhibition of PTP, 100 μm Na₃VO₄ or anti-RPTPα antibody (1 μg/ml) was added to the whole-cell patch pipette. Aa, Relative changes of G_in caused by a 50 Hz AP train was delivered at 0 s with (cyan) or without (purple) Na₃VO₄ in the patch pipette. The LTP-IE caused by the 50 Hz AP train in the presence of intracellular Na₃VO₄ was similar to the somatic conditioning (10 Hz for 2 s, gray), which was reproduced from Figure 1A for comparison. Insets, AP responses to 50 Hz 2 s somatic AP train (top) and subthreshold voltage responses for measuring G_in with the same color code as the main panel (bottom; black, control). Ab, The peak values for distal dendritic [Ca²⁺]_i evoked by a 50 Hz AP train are compared between conditions with or without intracellular Na₃VO₄. Ba, Test for specificity of the anti-RPTPα antibody. Ctrl siRNA, Nontargeting siRNA; RPTPα siRNA, RPTPα-targeting siRNA. Bb, Relative changes of G_in caused by a 50 Hz AP train with intracellular application of anti-RPTPα antibody (green filled symbols) or isotype antibody (green open symbols). In addition, the effects of PMA on G_in changes after a 10 Hz AP train are superimposed (orange). For comparison, somatic conditioning-induced ΔG_in (gray) was reproduced from Figure 1A. Insets, Subthreshold voltage responses for measuring G_in with the same color codes as the main panel. Bc, Summary for ΔG_in measured at 30 min after different conditionings: 10 Hz AP train (control), 50 Hz AP train (50 Hz), 50 Hz AP train with intracellular Na₃VO₄ (50 Hz + VO4), anti-RPTPα Ab^L (50 Hz + Ab^L), anti-RPTPα Ab^M (50 Hz + Ab^M), non-immunized Ab (50 Hz + ctrl Ab) and 10 Hz AP in the presence of PMA (10 Hz + PMA). n.s., No statistical significance. ***p < 0.005.