EVIDENCE FOR 2 TYPES OF NON-NMDA RECEPTORS IN RAT CEREBELLAR PURKINJE-CELLS MAINTAINED IN SLICE CULTURES

Pharmacological properties of non-MNDA receptors were investigated in Purkinje cells grown in rat cerebellar slice cultures and recorded in the whole-cell configuration of the patch-clamp technique. Dose-response curves for AMPA and domoate suggest that AMPA, in the concentration range tested, activated only AMPA receptors whereas, domoate activated two types of receptors, probably AMPA and kainate receptors, with EC(50) values of 8 and 0.5 mu M, respectively. The Scatchard analysis of the dose-response relationship for domoate also suggest that both kainate and AMPA receptors were activated by domoate with approximate affinities of 5 and 0.07 mu M(-1), respectively. The non-competitive non-NMDA receptors antagonist, GYKI 52466, reduced the amplitude of both AMPA- and domoate-activated currents, with a greater potency in reducing currents evoked by AMPA (IC50 = 10 mu M) than those induced by domoate (IC50 = 105 mu M). These results suggest that, in addition to AMPA receptors, Purkinje cells express kainate receptors and that these two types of non-NMDA receptors can be distinguished from each other on the basis of several pharmacological properties, including affinity for AMPA, domoate and GYKI 52466.