Biliary copper excretion in the chicken.

A series of experiments were performed to examine the nature of biliary copper excretion in the chicken. Gallbladder and hepatic bile were collected from chickens fed diets that altered copper excretion. Bile was fractionated using gel filtration chromatography and SDS-PAGE. Chicks fed the control diet excreted copper that was bound primarily to a protein aggregate of greater than 600,000 daltons and secondarily, to a 7400 dalton compound. When biliary copper levels were elevated, the distribution of copper associated with the binding compounds was changed. Both the proportion and the absolute amounts of copper in the secondary pool increased dramatically when biliary copper increased. The excretion patterns observed in the control animals are believed to represent the steady-state distribution of copper in bile. A similar distribution was observed with rat bile that was obtained under steady-state conditions. These distribution patterns differ from those reported by other investigators who examined biliary copper excretion in the rat using different experimental conditions.