Altered calcium dynamics in cultured cerebellar cells from IP3R1-deficient mice.

Intracellular calcium release in response to bath-applied quisqualate or caffeine was examined in cerebellar primary cultures of type-1-inositol-1,4,5-trisphosphate-receptor (IP3R1)- deficient mice. Under [Ca2+]o-free conditions, calcium release in response to 10 microM quisqualate was significantly reduced in Purkinje cells, but was unaffected in granule cells, suggesting that different subtypes of IP3 receptors contribute to the metabotropic glutamate response in these cells. In addition, calcium release in response to 10 mM caffeine under [Ca2+]o-free conditions was not impaired in cerebellar cells, suggesting that IICR and CICR are independently regulated in cerebellar cells. Moreover, in both wild-type and homozygous mutant mice, CICR in granule cells was approximately 6 times greater than in Purkinje cells.