Critical Roles of VoltageDependent Sodium Channel

Authors: Ke Wang Jihong Cui Yijun Cai Fang Wang Yi Li Wucheng Tao Hui Xiang

Publish Date: 2009/04/21

Volume: 29, Issue: 8, Pages: 1131-

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Abstract

The developmental changes of the sodium channel and construction of synapse connection were studied in cerebral cortical pyramidal neurons of rats at different age groups We used wholecell patchclamp recordings to characterize electrophysiological properties of cortical neurons at different age stages including the sodium currents APs evoked by depolarizing current and shortterm plasticity of the eEPSCs The result shows that the sodium currents undergo a hyperpolarizing shift in activation process and acceleration of activation and inactivation with age The maximal sodium current also increased with maturation and the evident difference appeared from P7–P11 with the day of birth as P0 to P12–P15 group The tendency of the sodium current density changes which exhibited the same properties as that of sodium current showed the significant increases from P19–P21 to P ≥ 22 group The APs’ parameters exhibited the agedependent changes except the threshold including the increase of the peak amplitude from P ≤ 6 to P16–P18 groups and the curtailment of duration and the timetopeak with age The amplitude of 1st eEPSC increased with maturation and STP displays depression at all observed groups In addition although STP also exhibited depression in response to last three stimulations in P ≥ 22 group the 2nd response showed the tendency of facilitation compared with the younger age groups Our results indicated that the cerebral cortical pyramidal neurons of rats are undergoing marked changes in the characteristics of their sodium channels with maturation which play a critical role in synaptogenesis and construction of the neuronal network

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