Inhibition of sugar transport across rat jejunum, in vivo, by cupric ions

Abstract

Cupric ions inhibit galactose absorption by in vivo perfused rat jejunum.It takes some delay for the inhibitory action to display its maximal levels, and previous exposure of the mucosa to Cu markedly increases inhibition.Copper effects were only scarcely reversed by saline solution washing, more effectively by EDTA and more so by dithioerythritol, in no case reaching control values.Absorption of L-sorbose, or that of galactose in the presence of 0.5 mM phlorizin, are not modified by 0.5 mM cupric ions.Cu action may be understood as a selective impairment of the phlorizin-sensitive sugar transport system by binding of the metal to prevailing thiol chemical groups of proteins at the brush border, located at different depth within the thickness of the membrane.