AUDITORY-CORTEX NEURONS - PRIMARY CULTURE AND ION-CHANNEL ACTIVITY INRAT

We have developed a primary dissociated cell culture of the fetal (E17 ) and post-natal (P0-P10) rat auditory cortex. Pyramidal and non-pyram idal cells had a mean cross-sectional diameter of 12.73 +/- 1.80 mu m (mean +/- S.D., n = 25) and 17.58 +/- 1.67 mu m (mean +/- S.D., n = 10 ), respectively, measured at 6 days in culture. These cells were viabl e for as long as 18-21 days. They expressed voltage-gated sodium and p otassium channel currents as early as one day in culture, and at vario us phases in cell culture. Sodium current, activated at membrane poten tials more positive than -60 mV, displayed fast activation and inactiv ation kinetics. Fifty percent inactivation of sodium channels occurred at a pre-pulse potential of -63 mV. Delayed rectifier potassium chann els were activated at potentials positive to -40 mV. Large hyperpolari zing constant current pulses elicited anode break action potentials, a nd large depolarizing constant current pulses exhibited rectification indicative of the delayed rectifying potassium channel activity.