Abstract

Excitatory amino acid (EAA) neurotransmitters induce postsynaptic depolarization by activating receptor-mediated cation conductances, a process known to underlie changes in synaptic efficacy. Using a patch-clamp method, we demonstrate here an EAA-dependent postsynaptic anion conductance mediated by EAA transporters present on cerebellar Purkinje cell bodies and dendrites in culture. This transporter-mediated current was modulated by neuronal activity: it exhibited facilitation for >20 min after transient depolarization accompanied by Ca²⁺ influx. Evidence is presented suggesting that the transporter facilitation is mediated by arachidonate release after Ca²⁺-dependent activation of phospholipase A₂, which exists in Purkinje cells. This postsynaptic reuptake system may represent a novel modulatory mechanism of synaptic transmission as well as prevent neuronal excitotoxicity.