Trans-ACPD-induced Ca²⁺ signals in cerebellar purkinie cells

A combination of intracellular recording and fluoromet-ric measurements of cytosolic calcium ([Ca²⁺]_i) was used to locate changes in [Ca²⁺]_i, induced by the specific meta-botropic glutamate receptor (mGluR) agonist trans-D, L-l-amino-l,3-cyclopentanedicarboxylic acid (t-ACPD), in Purkinje cells of rat cerebellar slices. Under voltage-clamp conditions, application of t-ACPD (100 (μM) induced an inward current accompanied by a large increase in [Ca²⁺]_i located primarily in the soma but also, to a lesser degree, in restricted parts of the dendrites. In contrast, elevations of [Ca²⁺]_i associated with calcium spikes were confined to the dendrites and inward currents of a similar amplitude induced by (RS)-α-amino-3-hydroxy-5-me-thyl-4-isoxazolepropionic acid (AMPA), an agonist of ionotropic glutamate receptors, did not raise [Ca²⁺]_i.