Effect of lead on the intestinal absorption of sodium selenite and selenomethionine ((75)Se) in chicks.

The present study was designed to investigate the interactions of lead with the intestinal absorption of selenium in chicks. The absorption of(75)Se-selenite and(75)Se-methionine was determined in 3-wk-old white Leghorn cockerels using both thein situ ligated intestinal loop procedure and oral administration of the isotopes. The highest lead concentration (1 mM) significantly reduced the percentage of(75)Se-selenite absorbed from thein situ ligated duodenal loop, but did not influence the retention of the orally administered isotope. Neither was the absorption of(75)Se-methionine affected by the presence of Pb in the intraduodenal dosing solution. The above experiments suggest that the direct luminal interaction of lead with the absorption of selenium is not of practical importance. On the other hand, feeding 1000 ppm Pb in the diet prior to the measurement of selenium absorption significantly reduced the transfer of the radioactive selenite from the intestinal lumen to the body. The mechanism of this effect involved enhanced retention of the(75)Se-selenite by the intestinal tissue. The inhibitory effect of lead exposure on selenium absorption also appeared to be alleviated by the increase in the dietary selenium content.