Voltage-activated potassium currents in acutely dissociated hippocampal dentate gyrus neurons from neonatal rats

We have studied outward currents of neurons acutely dissociated from the dentate gyrus region of hippocampus using whole-cell and perforated patch recordings. Depolarizing voltage commands activated sustained outward currents at all age tested (P5-P30). Outward currents were blocked by tetraethylammonium (10 mM) but not 4-aminopyridine (25 mM). Comparison of sustained potassium current during postnatal development showed a significant increase in current amplitude with age reaching a peak between P20 and P30. These results suggest an overall increase in the number of voltage-dependent ion channels during development, specifically those underlying TEA-sensitive potassium currents.