Distinct GABA and glutamate receptors may share a common channel in Aplysia neurons

Using a microperfusion technique for rapid application of agonists to single identified voltage-clamped neurons of the marine mollusc Aplysia, chloride conductances elicited by gamma-aminobutyric acid (GABA) and L-glutamate were found to differ in rates of activation and desensitization, voltage dependence and dose-response relations. In spite of these marked differences, the two responses showed strong interaction: previous application of GABA could completely block the responses to glutamate while previous application of glutamate decreased the response to GABA. This interaction was not due to transmembrane chloride redistribution, and is probably not cross receptor blockade. Cross-desensitization of GABA and glutamate responses suggest that distinct receptors activate a common ion channel.