Abstract
Studies were conducted to clarify the effect of dietary protein on the development in rats poisoned with lead, and the following results were obtained.
(1) The amounts of exogenous lead in the whole brain and blood of low protein group were higher than those of high protein group.
(2) Body weight gain per gram of dietary protein in the control group was higher than that in the lead-administered group.
To elucidate these mechanisms, the transferred amount of both lead and amino acids were measured. The rat small intestine, to which 1ml of casein solution, 1ml of lead nitrate solution and trypsin were packed, was incubated for 60minutes. The amount of lead transferred from intestinal mucosa to medium was markedly reduced by increasing amounts of protein added, and that of amino acid transferred was also inversely related to the lead concentration used. The activity of proteolytic enzyme was inhibited non-competitively by in vitro addition of lead, which Ki value was obtained to be 0.0015M.
