Intestinal absorption of cationic and anionic ferric colloids and complexes: biochemical, histochemical and morphological observations in rats.

This experiment was undertaken to study the possible difference in the intestinal iron absorption efficiency among iron compounds with different electric charges. Observation of rats given oral administration of 59Fe-labeled cationic cacodylate ferric (59Fe-Cac) colloid, anionic citrate ferric (59Fe-Cit) colloid, cationic 59Fe-Cac complex and anionic 59Fe-Cit complex revealed that iron absorption was more efficient in the 59Fe-Cac colloid, moderate in the 59Fe-Cac complex, low in the 59Fe-Cit colloid, and lowest in the 59Fe- cases given 59Fe-Cac colloid and 59Fe-Cac complex, a very high ratio activity was found in the liver and in the erythrocyte or hemoglobin in circulating blood, while the blood plasma, bone marrow, and spleen were low in activity. Histochemical observations of rat jejunal mucosa exposed independently for 10 min to the Fe-Cac colloid, anionic Fe-Cit colloid, and Fe-Cac and Fe-Cit complexes revealed that the cationic Fe-Cac colloid and Fe-Cac complex adhered to the luminal surface of the mucosa covering the apical area of villi with some ferric iron in the capillaries, while the anionic Fe-Cit colloid and complex did not adhere to the epithelial cells and were found free in the jejunal lumen. Electron microscopy revealed that Fe-Cac colloid particles were taken into epithelial cells by pinocytosis at the webs of microvilli, moved to the Golgi area, exocytosed to the intercellular spaces, and then translocated into the basement membrane toward blood capillaries.