Effects of Ang-(1-7) on LTP in COX-2-deficient mice. (A) In heterozygous COX-2-deficient mice (+/−), Ang-(1-7) neither at 0.5 μM (n = 7) nor at 0.01 μM (n = 7) was able to change the magnitude of LA-LTP in comparison to drug-free controls. (B) In homozygous COX-2-deficient mice (−/−), 0.01 μM Ang-(1-7) (n = 9) elicited a significant enhancement of LA-LTP. This enhancement of LTP could be blocked by 200 μM L-NAME (n = 7). For comparison, the control LTP recorded in COX-2−/− mice is also presented. (A,B) Application of high-frequency stimulation (HFS; 2 × 100 Hz, duration 1 sec, interval 30 sec) at time 0. Data points represent averaged amplitudes (mean ± SEM) normalized with respect to baseline values. (C) Bar histogram of data points shown in Figures 3 and 4, as averaged 55–60 min after HFS and normalized with respect to baseline (mean ± SEM). Significant differences are indicated; (**) P < 0.001.