Gastrointestinal absorption, tissue retention, and urinary excretion of dietary aluminum in rats determined by using 26Al.

We used accelerator mass spectrometry (AMS) and 26AI to study the plasma concentration, urinary excretion, and retention in bone, brain, and liver of a single dose of a dietary concentration of aluminum ingested either with or without citrate by 2-month-old Wistar rats. In the absence of citrate, cumulative urinary excretion and skeleton retention were each approximately 0.05% of the total 26AI dose ingested. 26AI retention in brain and liver were approximately 4 x 10(-8) and 2 x 10(-6), respectively. Concomitant citrate intake increased these median values by about two- to fivefold, although this factor was highly variable in individual rats. Independent of citrate administration, 90% of the 26AI excreted in urine (measured cumulatively over 30 days) was excreted within the first 48 h. Uptake by bone was rapid (approximately 1 h) and permanent over the 30-day duration of the experiment.