Calcium Release and Cerebellar Purkinje Neurons.

The following is an update on research funded by NAF in 1999.

A ubiquitous intracellular signaling pathway is the cytosolic free calcium concentration ([[Ca.sup.2]+.sub.i.]) At rest, cells maintain ([[Ca.sup.2]+.sub.i]) low, orders of magnitude lower than that in the extracellular plasma. By opening calcium selective pores, calcium is allowed to flow from outside of the cell into the cytosol, or is released from specialized intracellular calcium stores.

The increase in ([[Ca.sup.2]+.sub.i]) is a signal which activates diverse calcium dependent mechanisms such as secretion, contraction, or alterations in membrane excitability. One calcium channel located on the surface of the calcium stores is ligand-gated and is activated by inositol trisphosphate [InsP.sub.3]. [InsP.sub..3] receptors are found abundantly in the body, including in the CNS. The malfunction of the [InsP.sub.3] signaling pathway in the CNS has devastating consequences, the main features of which are …