Effects of Human Alimentary Secretions on 64cu Diffusion in an in Vitro System

Abstract

Human alimentary secretions are known to form soluble complexes with copper. The passive diffusion rate of 64Cu complexed to human saliva, gastric juice, and bile was determined and compared with that of known synthetic complexing agents. The study was performed using a two-piece glass diffusion apparatus which permitted continuous sampling from each compartment. It was shown that whereas copper diffusion was unimpaired by saliva or gastric juice, it was markedly inhibited by bile. The most likely explanation for this phenomenon is either that copper is bound by a macromolecular component of bile or that a low molecular weight complex is formed with some biliary component and undergoes polymerization. Which of these is applicable has not yet been determined. The possible role of such a mechanism in the regulation of gastrointestinal copper absorption is discussed.