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.