The electrophysiological properties of potassium ion channels are regarded as a basic index for determining the functional differentiation of neural stem cells.In this study,neural stem cells from the hippocampus of newborn rats were induced to differentiate with neurotrophic growth factor,and the electrophysiological properties of the voltage-gated potassium ion channels were observed.Immunofluorescence staining showed that the rapidly proliferating neural stem cells formed spheres in vitro that expressed high levels of nestin.The differentiated neurons were shown to express neuron-specific enolase.Flow cytometric analysis revealed that the neural stem cells were actively dividing and the percentage of cells in the S+G2/M phase was high.However,the ratio of cells in the S+G2/M phase decreased obviously as differentiation proceeded.Whole-cell patch-clamp recordings revealed apparent changes in potassium ion currents as the neurons differentiated.The potassium ion currents consisted of one transient outward potassium ion current and one delayed rectifier potassium ion current,which were blocked by 4-aminopyridine and tetraethylammonium,respectively.The experimental findings indicate that neural stem cells from newborn rat hippocampus could be cultured and induced to differentiate into functional neurons under defined conditions in vitro.The differentiated neurons expressed two types of outward potassium ion currents similar to those of mature neurons in vivo. The electrophysiological properties of potassium ion channels are considered as a basic index for determining the functional differentiation of neural stem cells. In this study, neural stem cells from the hippocampus of newborn rats were induced to differentiate with neurotrophic growth factor, and the electrophysiological properties of the voltage-gated potassium ion channels were observed. Immunofluorescence staining staining showed that the rapidly proliferating neural stem cells formed spheres in vitro that expressed high levels of nestin. differentiated neurons were shown to express neuron-specific enolase. Flow cytometric analysis revealed that the neural stem cells were actively dividing and the percentage of cells in the S + G2 / M phase was high. However, the ratio of cells in the S + G2 / M phase decreased obviously as the differentiation proceeded. changes in potassium ion currents as the neurons differentiated one transient outward potassium ion current and one delayed rectifier potassium ion current, which are blocked by 4-aminopyridine and tetraethylammonium, respectively.. The experimental anastomosis of neural stem cells from newborn rat hippocampus could be cultured and induced to differentiate into functional neurons under defined conditions in vitro. The differentiated neurons expressed two types of outward potassium ion similar similar to those of mature neurons in vivo.