Effect of calcium and magnesium ions on the intestinal absorption of oleic acid in vitro.

The effect of Ca++ and Mg++ upon intestinal absorption of oleic acid was investigated using two in vitro models: rat isolated jejunal loops at 30 degrees C and 37 degrees C and mouse jejunal explants at 37 degrees C. At 30 degrees C or at 37 degrees C, Ca++ significantly increased 14C oleic acid uptake by rat isolated jejunal loops or mouse jejunal explants; at 37 degrees C, Ca++ significantly enhanced lipid exocytosis in rat intestinal loops but not in mouse jejunal explants; in both models, in the presence of Ca++ and at 37 degrees C, Mg++ significantly improved the esterification of oleic acid phospholipids and triacylglycerols, as shown by the increase in triacyglycerol synthesis in rat isolated intestinal loops or by the increase in triacylglycerols recovered from the incubation media of mouse jejunal explants; experiments carried out with rat isolated jejunal loops highlighted the determinant role of temperature in oleic acid absorption processes. The present work shows that the simultaneous presence of Ca++ and Mg++ did not impede oleic acid absorption processes but, on the contrary, enhanced them.