Copper transfer through the intestinal wall. Serosal release of metallothionein.
The elucidation of the molecular side of copper transport in biological systems is a promising task. In this context the transfer of ingested copper into the portal blood plasma was examined. Intralumenal addition of 200 microM copper caused the release of Cu-thionein into the venous effluent. This Cu-thionein became detectable after prior perfusion of the porcine small bowel using a modified isotonic phosphate-buffered saline (Pi/NaCl) medium. The protein was characterized by gel chromatography, luminescence, electronic absorption and immunological identification. ELISA and immunoblotting employing a murine monoclonal antibody to rat liver metallothionein-I proved to be most convenient. Using buffer-loaded sacs of porcine jejunum into which Cu2+, Zn2+ and Cd2+ were added, the release of metallothionein into the serosal fluid was successfully seen by ELISA. The observed excretion of metallothionein into the portal compartment may be a genuine metal transport system for many biochemically active metals.
Felix
K
K
Anorganische Biochemie, Physiologisch-chemisches Institut der Universität Tübingen, Federal Republic of Germany.
Nagel
W
W
Hartmann
H J
HJ
Weser
U
U
D000818:Animals; D001693:Biological Transport, Active; D003300:Copper / Q000378:metabolism*; D066298:In Vitro Techniques; D007583:Jejunum / Q000378:metabolism*; D008102:Liver Circulation; D008668:Metallothionein / Q000097:blood / Q000378:metabolism*; D010477:Perfusion; D013552:Swine
D003300:Copper; D008668:Metallothionein