SINGLE-CHANNEL ACTIVITY CORRELATED WITH MEDIUM-DURATION, CA-DEPENDENTK-CURRENT IN CULTURED RAT HIPPOCAMPAL-NEURONS

Whole-cell voltage- and patch-clamp techniques were used to record the calcium-dependent component of I-mAHP and correlated single-channel a ctivity in postnatal cultured rat hippocampal neurons. The Ca-dependen t I-mAHP was elicited by voltage steps to + 10 mV from a holding poten tial of -50 mV in the whole-cell mode. In cell-attached patches, singl e currents of similar to 2 pA were observed following spontaneous acti on currents. The duration of ensemble-averaged single-channel activity was very similar to that of the whole-cell I-mAHP similar to 100 ms. Both whole-cell current and single-channel activity could be blocked b y bath-applied cadmium, 200 mu M. Vigorous channel activity was evoked by bursts of action potentials that are known to elicit Ca-dependent AHPs. We conclude that this channel is a candidate for mediating I-mAH P.