L-AP4 inhibits calcium currents and synaptic transmission via a G-protein- coupled glutamate receptor

P. Q. Trombley, G. L. Westbrook

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174 Scopus citations


The AP4 (2-amino-4-phosphonobutyrate) receptor is a presynaptic glutamate receptor that inhibits transmitter release via an unknown mechanism. We examined the action of L-AP4 on voltage-dependent calcium currents and excitatory synaptic transmission on cultured olfactory bulb neurons using whole-cell voltage-clamp methods. In neurons dialyzed with GTP, L-AP4 inhibited high-threshold calcium currents evoked in barium solutions. The inhibition was irreversible in the presence of GTP-γ-S and blocked by removing intracellular Mg2+ or by preincubation with pertussis toxin (PTX), consistent with the involvement of a PTX-sensitive G-protein. Dialysis with staurosporine or buffering of intracellular calcium to pCa <8 did not block the action of L-AP4, suggesting that protein phosphorylation or release of intracellular calcium stores was not involved in calcium current inhibition under these experimental conditions. PTX also blocked the L-AP4-induced inhibition of monosynaptic EPSPs evoked by intracellular stimulation of cultured mitral cells. These results suggest that the presynaptic AP4 receptor is a G-protein-coupled glutamate receptor, and that inhibition of calcium influx by a membrane-delimited action of a G-protein may account for L-AP4-induced presynaptic inhibition.

Original languageEnglish (US)
Pages (from-to)2043-2050
Number of pages8
JournalJournal of Neuroscience
Issue number6
StatePublished - 1992

ASJC Scopus subject areas

  • Neuroscience(all)


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