The Absorption of the Lead Cation from the Intestine of the Rat

Abstract

The gastrointestinal absorption of lead was studied using two techniques, one in vitro, the other in vivo. The in vitro technique used was that of everted intestinal sacs. The in vivo method was a whole body study where rats were dosed intragastrically with a known dose of radiolabelled lead acetate solution and sacrificed at time intervals after administration. The distribution of lead within the tissue was investigated by the application of agar to remove the apical glycocalyx or by scraping the incubated tissue to remove the mucosal layer. The interaction of lead with the tissue was altered by the use of a number of agents in vitro. The effect of these agents on the tissue-binding of a chelated lead complex was also studied. The in vivo absorption of lead was compared to that of iron and sodium cations. The effect on lead absorption of food was examined, both in the form of the normal rat diet and as individual components ie. an energy source, a chelating agent and fibre. Some comparison was made with the effects of these factors on the absorption of iron. The absorption of lead by weanling rats was examined. From the experimental data obtained in these studies it was concluded that lead transport by the intestine is a passive process. The interaction of lead cations with the tissue is a mainly surface phenomenon. Lead absorption is reduced by the presence of food in the intestine, the main effect being that of fibre. The age of the rat also affectedthe extent of absorption.