Changes of N-methyl-D-aspartate activated channels of cerebellar granule cells with days in culture

N-Methyl-D-Aspartate (NMDA) activated channels were studied in enzymatically dissociated cerebellar granule cells primary cultures. Measurements of single channel currents were made on different days in culture. Changes in the electrophysiological behavior of NMDA-activated channels, which were dependent on the time in culture, were found. The variations of single channel maximum conductance during the developement of the cells in culture were detected. Three different characteristic periods could be distinguished: the first period (1-3 days) in which the conductance assumed a value of 15.5 pS; the second one (5-8 days) characterized by a value of 35.7 pS and the last one (9-11 days) in which the conductance reached values of 46.8 pS. Moreover mean open time of NMDA-activated channels was less than 1 msec during the first two days in culture and stabilized at 3 to 6 msec around the fifth day.