Developmental time courses of Na and Ca spikes in neuroblastoma X glioma hybrid cells

The developmental time course of membrane excitability in neuroblastoma X glioma hybrid cells (NG108-15) was analyzed by measuring the electrical potential at each culture day after dBcAMP treatment. The maximum rate of rises of Na and Ca spikes which reflect their inward currents were measured in appropriate medium respectively. The Ca spike began to appear at 2-3 days in culture and reached its maximum on the fifth day. The Na spike began to appear at 3-4 days in culture and was completed on the seventh day. After then Ca and Na spikes remained constant and did not decrease even on the eighteenth day. Electrical excitability of the hybrid cells, as a whole, developed stepwise and was completed on the seventh day of culture.