THE EFFECT OF AGE ON CALCIUM DYNAMICS IN RAT-BRAIN IN-VIVO

Different biochemical changes accompany development and ageing. Howeve r, the time frame for a particular biochemical change may be different than that for another. In the ageing brain, neurological deficits rel ated to ageing have been suggested to be due to a breakdown of calcium (Ca++) homeostasis, and an increase in intracellular Ca++. To underst and the dynamics of calcium in CNS in relation to normal ageing. we ha ve determined Ca-45(++) uptake by the different regions of brain in yo ung (3 months) and aged (15 months) rats after a single i.v. injection of 90 mu Ci/kg Ca-45(++). In the aged group, the initial plasma conte nts of the tracer were higher than in the young rats (3 months). The m ean values of uptake (as fraction of injected dose/g x 10(5)) of Ca-45 at different sites were higher in the 15-month-old animals than in th e young rats (viz. cortex: 50 vs. 26; hippocampus: 90 vs. 46 and putam en: 54 vs. 30 at 120 min). Computer simulation of the uptake data indi cated that the values of most of the fractional transport rates were s imilar or lower in the aged compared to the controls. However, the ste ady state ratio of intra/extracellular Ca++ was higher in the 15-month -old animals, suggestive of intracellular accumulation of Ca++.