Ionic currents in PC12 cells differentiated into neuron-like cells by a cultured-sciatic nerve conditioned medium

The present work deals with the identification of the ionic currents found in PC12 cells differentiated into neuron-like cells by a 9-11-day cultured-sciatic nerve conditioned medium (CM). PC12 whole-cell currents were measured after chronic exposure to CM. The results obtained in these CM-treated cells reveal that the functional expression of Ca2+ currents is increased, that Na+ currents are not affected, and that a transient K+ current and a K+ delayed rectifier (K(+)dr) current are increased. The combination of nifedipine and omega -conotoxin GVIA (omega -CgTX) does not block completely the increased functional expression of the Ca2+ current. The remaining current is blocked by omega -agatoxin TK indicating that P/Q-type channels are additionally contributing to the increase in Ca2+ current. NGF-treated PC12 cells, used as positive controls, confirm that NGF increases the expression of voltage-dependent Na+ currents and of Ca2+ currents. In addition, we found that NGF also increases a K(+)dr-type current in these cells. The results obtained with the CM might be due to a molecule or a mixture of molecules released into the medium by the 9-11-day cultured sciatic nerves. (C) 2001 Elsevier Science B.V. All rights reserved.