LASTING EFFECTS OF GLUTAMATE ON NUCLEAR CALCIUM-CONCENTRATION IN CULTURED RAT HIPPOCAMPAL-NEURONS - REGULATION BY CALCIUM STORES

1. Changes in free intracellular calcium concentrations ([Ca2+](i)) we re measured in the nucleus and perinuclear regions of cultured rat hip pocampal neurons using either fura-2 or fluo-3 calcium indicators. 2. Brief application of glutamate caused a transient rise of [Ca2+](i) in all cell compartments, which recovered to pre-drug levels in all but the nuclear region. The new, higher level of nuclear calcium ([Ca2+](n )) was sustained for as long as the cell was monitored. 3. The new lev el of [Ca2+](n) was dependent on the magnitude of the calcium transien t, and was higher in older cells in culture, but it did not affect res ponses to subsequent applications of glutamate. 4. The sustained eleva tion of [Ca2+](n) was prevented by drugs which affect calcium stores ( caffeine, ryanodine and Ruthenium Red), indicating that an extranuclea r calcium store interacts with [Ca2+](n).