Stimulation of mucosal uptake of selenium from selenite by L-cysteine in sheep small intestine.
The influence of cysteine (Cys) on mucosal uptake of 75Se-labeled selenite in sheep midjejunum was investigated using a short-term uptake technique. L-Cys (concn.: 1.0 mmol/L) significantly stimulated uptake of Se from selenite (concn.: 10 mumols/L). The stimulatory effect of L-Cys on mucosal uptake of Se from selenite was Na(+)- and pH-dependent. In the absence of Na+, or at an acidic pH (5.0), the stimulatory effect of L-Cys was abolished. L-alanine and L-lysine, but not L-glutamic acid inhibited uptake of Se from selenite in the presence of L-Cys. Preincubation of mucosal preparations with 10 mmol/L L-Cys produced enhanced mucosal uptake of Se from selenite. It is concluded from these results that L-Cys stimulates absorption of Se from selenite probably by generation of selenodicysteine and maybe cysteine selenopersulfide that are subsequently transported across the intestinal brush border membrane by Na(+)-dependent amino acid carriers. Furthermore, intracellular generation of selenodicysteine might contribute to the uptake of Se from selenite by maintaining the concentration gradient for diffusive uptake of selenite.
Würmli
R
R
Institute of Veterinary Physiology, University of Zürich, Switzerland.
Wolffram
S
S
Stingelin
Y
Y
Scharrer
E
E
D000596:Amino Acids / Q000494:pharmacology; D000818:Animals; D003545:Cysteine / Q000494:pharmacology*; D005260:Female; D006863:Hydrogen-Ion Concentration; D007413:Intestinal Mucosa / Q000187:drug effects / Q000378:metabolism*; D007421:Intestine, Small / Q000378:metabolism; D007583:Jejunum / Q000187:drug effects / Q000378:metabolism; D008297:Male; D020887:Selenious Acid; D012643:Selenium / Q000493:pharmacokinetics*; D012756:Sheep
D000596:Amino Acids; D020887:Selenious Acid; D012643:Selenium; D003545:Cysteine