FUNCTIONAL DIVERSITY OF GABA-ACTIVATED CL- CURRENTS IN PURKINJE VERSUS GRANULE NEURONS IN RAT CEREBELLAR SLICES

In rat cerebellar slices, we compared whole-cell recordings of spontan eous inhibitory postsynaptic currents (sIPSCs) with Cl- currents resul ting from pulses of GABA (1 mM, <2 ms) to outside-out patches from Pur kinje and granule neurons. sIPSCs in Purkinje cells decayed with a sin gle fast exponential, as previously reported, whereas in granule cells sIPSC decay was best described by the sum of a fast and a slow expone ntial curve, with a variable contribution of the slow component to the peak current. GABA pulses to nucleated patches from granule cells eli cited Cl- currents with decays similar to sIPSC decays, whereas in pat ches from Purkinje neurons GABA pulses produced Cl- currents decaying largely with a fast component, but often followed by a slower exponent ial. GABA concentration steps produced rapidly desensitizing currents in patches from both cerebellar neurons. In distinct cerebellar neuron s, specific functional properties of GABA(A) receptors may relate to t he presence of distinct receptor subtypes.