Aluminum absorption by rat duodenum: further evidence of energy-dependent uptake.

Duodenums of intact anaesthetised rats have been perfused with saline-bicarbonate buffer (pH 8.5), containing AlCl3, across a range of concentrations 0-300 microM. A linear relation between rate of uptake and perfusate Al concentration was found. The clearance of Al from the lumen was also studied with the mean perfusate concentration of 60 microM, in the presence of certain inhibitors. The clearance was significantly reduced by NaCN(1 mM) or dinitrophenol (0.1 mM) in the perfusate, and by prior perfusion with vanadate (10 microM) in saline. No effect was observed after colchicine (25 micrograms) was administered i.v. 3 h before perfusion, but vincristine (10 micrograms) given similarly reduced clearance significantly. Verapamil (25 micrograms/ml) in the perfusate caused a small, just significant, reduction in clearance. These data further characterise duodenal absorption of Al under physiological conditions and suggest that energy-dependent transport plays an important role in its uptake. Calcium channels may provide an additional entry site.