EFFECT OF ORAL ALUMINUM CITRATE ON SHORT-TERM TISSUE DISTRIBUTION OF ALUMINUM

Aluminium (Al) concentrations in the plasma, bone, lung, liver, kidney , spleen, duodenum and brain of rats were measured 2, 4 and 24 hr afte r a single oral dose of 0.46 mmol as Al citrate (1:5 molar ratio). Com pared with control animals, very high concentrations were found at 2 h r post-administration in plasma (539 mug/litre) and in all tissues exc ept the brain where Al did not change throughout the 24-hr period. The increased levels in the liver (161 ng/g) and lung (89.7 ng/g) at 2 hr were maintained until 4 hr and then decreased. At 24 hr the plasma va lue decreased to 24.6 mug/litre as compared with the peak value of 539 mug/litre. In a typical soft tissue such as the kidney the peak at 2 hr of 682 ng/g decreased to 241 ng/g, which was still more than 10-fol d greater than the control level. Uniquely, in the case of bone Al inc reased throughout the period of the experiment. Our results indicate t hat Al in the citrate form is readily absorbed and that it appears to equilibrate rapidly between plasma and the intracellular compartments of most soft tissues but does not readily permeate the blood-brain bar rier. In a group of rats previously given silicic acid in the drinking water and co-administered with the Al dose, the tissue Al distributio n pattern at 4 hr post-administration was modified in comparison with the test animals not loaded with silicic acid. Al concentrations in pl asma and soft tissues were significantly reduced except for the spleen , in which Al increased, and there was complete inhibition of the very high Al uptake/deposition in bone.