Early studies by Pendleton and West (1) in 1932 demonstrated that urea moved from the blood into the small intestine in uremic dogs. In 1946, Twiss and Kolff (2) showed in uremic patients that urea could be removed when an isotonic solution was perfused through an isolated in testinalloop. Since these early studies had demonstrated the presence of urea and its removal from the gastrointestinal tract, Yatzidis (3) in 1964 investigated the use of activated charcoal for the removal of uremic wastes from the intestinal tract. In addition to Yatzidis' studies with char coal, other investigations...