Calcium currents in pyramidal neurons acutely dissociated from the rat frontal cortex: a study by the nystatin perforated patch technique.

We studied electrical and pharmacological properties of voltage-activated Ca2+ currents (ICa) in freshly dissociated rat frontal cortical pyramidal neurons by using nystatin perforated patch and conventional patch-clamp techniques. With either nystatin perforated patch technique or conventional patch-clamp technique, low voltage-activated ICa (LVA ICa) and high voltage-activated ICa (HVA ICa) were recorded. However, in conventional whole-cell recording, HVA ICa ran down within 5-20 min, whereas the current remained stable for 50 min at least in nystatin perforated patch recording. The HVA ICa recorded by nystatin perforated patch technique was further classified to L-type, N-type and a current component resistant to both nicardipine and omega-conotoxin by their current kinetics, voltage- and drug-sensitivities. Present results suggest that the perforated patch technique is a useful method for studying the properties of high voltage-activated Ca2+ channels.