Distribution of Ca²⁺-permeable AMPA receptors among cultured rat cerebellar granule cells

Abstract

SOME AMPA receptors are permeable to Ca²⁺. It has been suggested that cultured rat cerebellar granule cells express Ca²⁺-permeable AMPA receptors, but their distribution at a single cell level is unknown. We report that AMPA (in the presence of cyclothiazide) induced Ca²⁺ entry (measured by Mn²⁺ quench of fura-2 fluorescence) and intracellular Ca²⁺ increases in cerebellar granule cells in the absence of extracellular Na⁺, supporting the presence of Ca²⁺-permeable AMPA receptors. Analysis of intracellular Ca²⁺ signals in single cells demonstrated a heterogeneous distribution of Ca²⁺-permeable AMPA receptors.