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 (I(Ca)) 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 I(Ca) (LVA I(Ca)) and high voltage-activated I(Ca) (HVA I(Ca)) were recorded. However, in conventional whole-cell recording, HVA I(Ca) ran down within 5-20 min, whereas the current remained stable for 50 min at least in nystatin perforated patch recording. The HVA I(Ca) 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.