Spermine (SP4+) one of the polyamines (PAs) switches paired pulse depression to facilitation in CA1 hippocampus (Brain Res 689(1995)189). In neocortex, relief from intracellular PA block of Ca2+ permeable GluR2-lacking-AMPAR in interneurons (INTs) may induce facilitation (Nature 401(1999)594). Moreover, extracellular SP potentiates GluR2-rich-AMPAR in CA1 pyramidal cells (PCs) (SFN-2002 online 540.8) that in addition contain GluR6(R) receptors linked to inhibitory INTs (J Neurosci 19(1999)653). These receptors are potentiated by extracellular SP (J.Neurosci.23(2003)1179) that might be released into the neuronal network from astrocytes (Glia 19(1997)171), specifically during ischemia-like conditions (Physiol Res 48(1999)S67). Here we studied the effect of SP on kainate-induced responses in PCs at acid pH as a model of ischemia. Non-enzymatically isolated CA1 PCs from 9-25 day old rats were identified by their localization in s. pyramidale; by acid-sensitive ion channels (ASIC) currents; and by GluR1-2-4 imm...