Figure 1.

Inhibition of CaMKII depresses potentiated and basal transmission in a dose-dependent manner. A, B, Single experiment (A) and summary graph (B; n = 5) showing the effect of Ant-CaMKIINtide (bath application; 3 μm) on basal (filled diamonds) and potentiated (open circles; arrow, 100 Hz, 1 s) transmission. A, Inset, Averaged (n = 10) basal fEPSP before and after 30 min drug application. Calibration: 5 ms, 0.2 mV. C, Percentage decrease in transmission after 30 min inhibitor applications at different concentrations is the same in LTP and naive pathways (diagonal line represents the ratio if the values of percentage inhibition of naive and percentage inhibition of potentiated responses are equal). D, Percentage decrease in basal transmission after 30 min as a function of inhibitor concentration (n = 5 for 0.5–5 μm; n = 2 for 7 μm). E, Superimposed results of the effect on basal transmission from interleaved experiments in which 5 μm different peptides containing the Ant segment was applied. Ant-CaMKIINtide (open squares; n = 5) and Ant-AIP (horizontal lines; n = 7) are CaMKII inhibitors. Ant (gray circles; n = 5) is the antennapedia segment alone, and ACSF is a control experiment (no peptide) in which the recirculating solution was changed at times similar to those used in test experiments (black circles; n = 4). F, Summary plot showing the percentage decrease in fEPSP (measured during the last 5 min of peptide application) from the same experiments as in E. The results from application of Ant- Tirap-R (n = 5), a peptide unrelated to CaMKII, were also included. Levels of significance in the post hoc pairwise Tukey's test, *p < 0.01; **p < 0.0005; NS, p > 0.5. Norm., Normalized.