Stimulation of lead absorption by vitamin D administration.

Two methods for the determination of lead absorption have been developed using the rat as the test animal. One is an everted intestinal sac method in which the time course of 210Pb transport across intestinal wall can be followed in vitro; and the other, 210Pb absorption from the intestine following gastric intubation can be followed in vivo. By using these techniques it can be clearly demonstrated that vitamin D markedly enhances lead absorption. Both techniques provide evidence that the distal small intestine is the major site of lead absorption and the site of greatest vitamin D stimulation. Lead acetate is apparently absorbed to the extent of 45% as it passes through the small intestine at a concentration of 0.01 mM.