Intracellular calcium mobilization triggered by a glutamate receptor in rat cultured hippocampal cells.

1. Intracellular free calcium ([Ca2+]i) was monitored by means of Fura‐2 fluorescence measurements in hippocampal cells in primary cultures from newborn rats. 2. In external media containing 200 microM‐DL‐2‐amino‐5‐phosphonovalerate and 1 mM‐kynurenate, but no added Ca2+, an increase in [Ca2+]i was observed in 30‐40% of cells examined in response to quisqualate or L‐glutamate. 3. Under such conditions, [Ca2+]i often increased gradually with a latency of a few seconds after application of the agonists. 4. Pre‐treatment of the cultured cells with pertussis toxin reduced the extent of quisqualate‐stimulated [Ca2+]i increase in Ca2+‐free media, but the percentage of the responsive cells was not affected appreciably. 5. It is concluded that quisqualate and L‐glutamate can trigger the release of Ca2+ from intracellular Ca2+ stores, most likely by activating a glutamate receptor coupled to a pertussis toxin‐sensitive G‐protein.