Tissue aluminium distribution in growing, mature and ageing rats: relationship to changes in gut, kidney and bone metabolism

The purpose of this study was to determine whether accumulation and turnover of aluminium differed among growing (2 month old), mature (8 month old) and ageing (19 month old) rats and assess whether these differences could be ascribed to physiological changes with age. One day after a large oral dose (0.8 mmol Al in 0.75 M citrate) growing rats had the highest concentrations of aluminium in tibias, whereas ageing rats had the highest concentrations of aluminium in kidneys. The half-life of aluminium in tibias (38 v. 58 v. 173 days in growing, mature and ageing rats, respectively) and kidneys (9 v. 12 v. 16 days) lengthened with age. According to stepwise multiple regression analysis, 73% variation in tibia aluminium concentrations was explained by final body weight of rats, length of time after dosing, tibia weights, haematocrits, urinary hydroxyproline excretion, ulna calcium concentrations, and urinary creatinine excretion but 57% variation in kidney aluminium concentrations was explained by length of time after dosing and feed intake. Although age, per se, was a significant predictor of spleen and liver aluminium concentrations, the measured changes in gut, kidney, bone and mineral metabolism were less predictive of aluminium concentrations in livers and spleens than in bone.