Changes in intracellular calcium in brain cells of aged rats

BACKGROUND:Studies have shown that voltage-dependent calcium influx,and enhancement of certain calcium-dependent processes in neurons,is related to aging.OBJECTIVE:To observe changes in intracellular calcium([Ca2+]i) in neurons of aged rats,and to compare with young rats.DESIGN,TIME AND SETTING:A randomized control experiment of neurophysiology was performed at the Central Laboratory of School of Pharmaceutical Science,China Medical University from June to August 2004.MATERIALS:Ten male,healthy,Wistar rats,19 months old,were selected for the aged group.Ten male,3-month-old,Wistar rats were selected for the young control group.Fura-2/AM was provided by the Institute of Pharmaceutical Research of Chinese Academy of Medical Sciences,and the F-2000 fluorospectrophotometer was a product of Hitachi,Japan.METHODS:Fluorescence Fura-2 spectrophotometer was used to measure [Ca2+]i in acutely dissociated brain cells of aged and young rats.The concentration of extracellular potassium was controlled by adding different volumes of chloridated potassium solution of high concentration.MAIN OUTCOME MEASURES:[Ca2+]i in neurons of young and aged rats in the presence of 1 mmol/L extracellular calcium concentration and 0 mmol/L(resting state),5,10,20,and 40 mmol/L extracellular potassium.Absolute increase of [Ca2+]i in neurons of young and aged rats when extracellular potassium was 5,10,20,40 mmol/L.RESULTS:In the presence of 1 mmol/L extracellular Ca2+ and 0 mmol/L(resting state),5,10,20,and 40 mmol/L extracellular potassium,[Ca2+]i in the neurons of aged rats was significantly less than that in young rats(P < 0.05).However,there was no significant difference in absolute [Ca2+]i increase induced by different concentrations of KCl between the aged and the young rats(P > 0.05).CONCLUSION:The overload of [Ca2+]i in neurons of aged rats is greater than that of young rats under the same circumstances.