Ca²⁺ release from Ca²⁺ stores, particularly from ryanodine-sensitive Ca²⁺ stores, is required for the induction of LTD in cultured cerebellar Purkinje cells

1. Primary-cultured cerebellar Purkinje cells (PCs) from mouse embryos were whole cell voltage clamped, and L-glutamate (Glu) was applied iontophoretically to the dendrite. Long-term depression (LTD) of Glu-evoked currents was induced through the conjunction of repeated depolarizations and Glu applications. 2. Thapsigargin, a specific inhibitor of Ca²⁺-ATPase on the endoplasmic reticulum, and ryanodine and ruthenium red, inhibitors of the ryanodine receptor, blocked the induction of LTD. 3. Thapsigargin and ryanodine alone did not affect influx of Ca²⁺ through voltage-gated Ca²⁺ channels and inward currents evoked by Glu applications. 4. Our results suggest that Ca²⁺ release from internal stores, particularly from ryanodine-sensitive stores, is necessary for the induction of LTD in cultured PCs.