Duodenal aluminum absorption in the rat: effect of vitamin D.
Aluminum absorption by the duodenum was studied with an in vivo isolated gut segment technique in vitamin D-deficient and vitamin D-replete rats. Aluminum uptake could be resolved into saturable and nonsaturable components. Both groups demonstrated an identical nonsaturable mechanism with an aluminum uptake of approximately 23% of the amount perfused per 100 mg dry intestinal weight. Saturable absorption was significantly lower in the vitamin D-deficient group (Jmax 6.9 +/- 1.4 microM X h-1 X 100 mg dry wt-1) than in the vitamin D-replete group (Jmax 13.0 +/- 2.7 microM X h-1 X 100 mg dry wt-1) (P less than 0.05). The presence of aluminum in the perfusion solutions reduced duodenal calcium absorption by 33% (P less than 0.02) in the vitamin D-replete group but not the vitamin D-deficient group. These results suggest that aluminum is absorbed in the duodenum by both a nonsaturable mechanism and a vitamin D-dependent saturable mechanism, for which it may compete with calcium.
D000535:Aluminum / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000378:metabolism; D004386:Duodenum / Q000378:metabolism; D007408:Intestinal Absorption; D008297:Male; D010477:Perfusion; D051381:Rats; D011919:Rats, Inbred Strains; D014807:Vitamin D / Q000502:physiology*; D014808:Vitamin D Deficiency / Q000378:metabolism
D014807:Vitamin D; D000535:Aluminum; D002118:Calcium