Abstract: The rat brain neurons taken from 15～17 days embryo were grown in dissociated cell culture and maintained in vitro for 3 weeks. The developmental process of the neurons was observed from early stage of development in terms of passive and active electrical properties. The neurons’ development could be morphological divided into stanes Ⅰ (from plating time to 6 days), Ⅱ(7～11 days), Ⅲ(12～21 days), and Ⅳ(21～22 days). The relative value of resting membrane potentials (RMP) for stages Ⅰ,Ⅱ ,Ⅲ , and Ⅳ was 1, 3.46, 4.07 and 6.54, respectively; the corresponding value of input resistances (Rin) was 1, 1.48, 2.53 and 4.56 respectively. The current-voltage curve in stages Ⅱ and Ⅲ was exponential in the direction of depolarization and the Rin’s change with time was nearly linear. Occurrence rate of spontaneous activitywas increased with prolongation of culture and the amplitude of evoked action potentials reached maximum during stages Ⅲ and Ⅳ. The results indicate that potassium ion channels develop slower in stages Ⅱ, faster in stagds Ⅰand Ⅲ and mature by the end of stage Ⅳ.

Key words: potassium channel, brain neuron, membrane resting parameters