Characterization of a Voltage-dependent Calcium Current in the Human Neuroblastoma Cell Line SH-SY5Y During Differentiation

In the presence of retinoic acid, cultured human neuroblastoma SH-SY5Y cells grow processes indicative of neuronal differentiation. A voltage-gated Ca current is already present in undifferentiated cells. A gradual increase of the Ca current density occurs during cell differentiation. According to kinetic and pharmacological properties, Ca currents in differentiated cells are indistinguishable from those elicitable in undifferentiated cells and resemble features of the high-voltage activated currents present in mammalian neuronal cells. omega-conotoxin strongly depresses high-voltage activated currents, both in undifferentiated and in differentiated SH-SY5Y cells. Interestingly, the Ca agonist Bay K 8644 is effective, albeit with great variability from cell to cell, only in differentiated cells and only when barium is the current carrier through the Ca channels. A diversity of high-voltage activated Ca channels of distinct pharmacology has been recently observed in other kinds of neurons. This requires a redefinition of the role that voltage-dependent Ca channel subtypes can play in mammalian neurons.