Fig. 3.

Effect of X/XO on PPF. PPF was examined every 10 min with four sets of paired pulses, with an interpair interval of 20 sec and an interpulse interval of 50 msec. The change in PPF was expressed as the percentage of PPF at 0 min (the ratio of the second response to the first response). There was no alteration in PPF until immediately after the washout of X/XO (20 and 2 μg/ml), when we observed a increase in PPF that coincided with transient depression induced by X/XO. We also observed decreases in PPF 20 and 30 min after the washout of X/XO that coincided with the slowly rising potentiation induced by X/XO. Error bars are SEM for six determinations. *Statistical significance with a paired Student's ttest (p < 0.05).