LTP is thought to be initiated by a transient activation of NMDA receptors causing an increase of [Ca2+]i in the cell. It has been reported that intracellular application of high Ca/CaM could mimic LTP without any electric stimulation. We investigated whether this application could cause the same kind of postsynaptic modifications of AMPA receptors as was seen with tetanus (see Andrasfalvy et al. SFN abstract 2001). The number of AMPA receptors, single-channel conductance, open probability and channel kinetics were examined after 5 min Ca/CaM treatment through the patch-pipette. We excised an outside-out patch from the dendrite and rapidly applied glutamate (10mM) and performed a non-stationary fluctuation analysis. We compared our result with other outside-out patches excised from electrically potentiated cells. Thus far the Ca/CaM application has produced the same type of changes in AMPA receptor properties as was seen following electric stimulation. The channel number was increased (N=3268 ± 454 vs 1726...