The influence of cytoplasmic Ca²⁺ elevation on spike encoding at cerebellar Purkenje cells in mice

Objective: To study the changes of the intrinsic electrophysiological characteristics of cerebellar Purkinje cells during the stage of the elevation of intracellular Ca²⁺ through micro-injected of IP₃ receptor excitomotor of Purkinje cells in cerebellar vermis.Methods: The sagittal slices of cerebellar vermis(400 μm) were prepared.The recordings of threshold potential of firing spike and absolute refractory period following each spike of cytoplasmic Ca²⁺ elevation cells were conducted in whole-cell model with an Axoclamp-2B amplifier;and electrical signals were inputted into pClamp 9.2 for data acquisition and analysis of inter-spike interval and standard deviation of spike timing.The changes in the intrinsic electrophysiological properties at Purkinje neurons during the elevation of intracellular Ca²⁺ were examined.Results: Shortly after the elevation of intracellular Ca²⁺,compared with before,refractory period of sequential spikes was shorten,the threshold potential of firing spikes was lower(P<0.001).Conclusions: The elevation of cytoplasmic Ca²⁺ alters the refractory period and threshold potential of sequential spikes,leads to increase of the excitability and deteriorated spike encoding of cerebellar Purkinje cells.