Changes of IA and IK from the pyramidal neurons at hippocampal CA1 during the early development of rats

Brain growth spurt (BGS) is the critical period of neuronal growth and synaptic connection. The voltage-gated K(+) channel is the key channel for maintenance of cell excitability and information transfer among neurons. The purpose of the present study is to investigate the critical period of voltage-gated K(+) channel development in hippocampal CA1 neurons during the BGS. Changes of voltage-gated K(+) currents in neurons from acutely isolated hippocampal CA1 brain slices of rats at different ages (0-4 weeks after birth) were recorded by the whole-cell patch-clamp technique. The depolarization voltage was set at +90 mV, and 0 week was set as the control group. The experimental results showed that, with increasing ages (1-4 weeks), the maximum current densities of IA increased by (16.14 ± 0.51)%, (81.73 ± 10.71)%, (106.72 ± 5.29)%, (134.58 ± 8.81)% (n = 10, P < 0.05), and the maximum current densities of IK increased by (16.75 ± 3.88)%, (134.01 ± 2.85)%, (180.56 ± 8.49)%, (194.5 ± 8.53)% (n = 10, P < 0.05), res