L-type calcium channels mediate synchronized spontaneous Ca2+spikes in cultured cortical networks

We have detected synchronized spontaneous Ca²⁺ spikes in cultured cortical networks in the presence of Mg²⁺. The synchronized spontaneous Ca²⁺ spikes are synaptically driven, as it is blocked by tetrodotoxin (TTX), and by the glutamate receptor antagonist CNQX/APV. The oscillatory activity is not influenced by GABA _A receptor antagonist picrotoxin, suggesting that they entirely rely on glutamatergic neurotransmission. We have also found that these Ca²⁺ spikes are dependent on an influx of extracellular Ca²⁺ but are independent of mobilization of Ca ²⁺ from intracellular Ca²⁺ stores. Ca²⁺ entry occurred primarily through L-type voltage-gated calcium channels (VGCCs), since nifedipine completely blocked these Ca²⁺ spikes