Objective To investigate the relationship between changes in Ca2+ concentration and unit discharge in the hippocampal neurons of epileptic rats.Methods Thirty-six healthy male Wistar rats were divided into three groups. Rats of the epilepsy group received an intraperitoneal injection of benzylpenicllin sodium at 6 million unit/kg; Rats of the epilepsy pretreatment group received 20 mg/kg of flunarizine at 14 and 2 hours before injection of benzylponicllin;the control group of rats received an intraperitoneal injection of normal saline.Three groups of rats were euthanized after recording of the unit discharge,and bilateral hippocampal cells were obtained to measure the cellular concentration of Ca2+ fluorescence using the new generation Ca2+ fluorescent dye Fluo-3-AM and flow cytometry.Results (1) A total of 24 units of hippocampal discharges were recorded in the control group.The average concentration Ca2+ fluorescence of the hippocampal neurons was 37.12±5.08.(2)A total of 78 units of hippocampal discharges were recorded in the epilepsy group.The average concentration of Ca2+fluorescence of the hippocampal neurons was 52.04±6.75.(3)A total of 47 units of hippocampal discharges were recorded in the epilepsy pretreatment group. The average concentration of Ca2+ fluorescence of the hippocampal neurons was 37.79±3.09.The correlation coefficient between the average concentration of Ca2+ fluorescence of the hippocampal neurons and the number of units of hippocampal discharge ( r=0.737,P＜0.01).Conclusion There is a positive correlation between changes in average concentration of Ca2+ fluorescence of the hippocampal neurons and the numbers of units of hippocampal discharge.