Beeinfluβt Calcitriol die orale Toxizität von Aluminium?

Abstract

The gastrointestinal absorption of aluminium has been shown to be markedly enhanced in uraemic rats. However, the precise mechanisms underlying this phenomenon have as yet not been elucidated. The present study examines the effect of vitamin D oh the intestinal absorption of aluminium in both tats with chronic renal failure and rats with intact kidneys. When vitamin D-deficient rats with normal renal function and vitamin D-replete controls were studied with a single oral dose of 11 mg aluminium, the latter excreted a significantly greater amount of the oral dose of aluminium in their urine (19.63 ± 9.75 vs 9.69 ± 3.78 µg Al/5d; P < 0.02). Furthermore, the post-load increase in the serum aluminium concentration was more pronounced in the vitamin D-replete animals. Aluminium administered i.v. resulted in similar urinary aluminium excretion rates in both groups indicating that vitamin D did not affect tissue binding and/or renal excretion of aluminium. In uraemic rats, regardless of their vitamin D status, administration of 1,25(OH)2D3 had no effect on the amount of urinary aluminium excretion after oral i.v. loads. These findings suggest that although in rats with normal renal function aluminium absorption appears to be partly vitamin D dependent, 1,25(OH)2D3 does not further augment the enhanced gastrointestinal absorption of aluminium in uraemia.