Mn absorption: The use of CACO-2 cells as a model of the intestinal epithelia

Abstract

Manganese uptake and transport were examined with CACO-2 cells grown on polyethylene (PET) or polycarbonate (PC) semipermeable membranes. Cells were grown in growth medium (DME + 10% fetal calf serum; 0.1 μmol Mn/L) for 21 days. Apical to basolateral transport rate of Mn was lower than the basolateral to apical transport rate. Apical to basolateral Mn uptake and transport were strictly concentration dependent, but basolateral to apical uptake and transport were saturable. When cells were grown in media containing 30 μmol/L of various metal ions, Ni and Cu depressed Mn transport substantially, but 30 μmol Mn/L increased Mn transport. Apical to basolateral transport was relatively unaffected by temperature, the presence of ligands, and/or competing ions, however, all of these factors decreased basolateral to apical transport. When equal amounts of 54Mn were put on both sides of the cellular monolayer, cells preferentially moved Mn to the apical side, creating an apical to basolateral concentration gradient for 54Mn. These results show that Mn uptake and transport by CACO-2 cells are processes that differ for the apical and basolateral membrane.