ANTISECRETORY FACTOR ENHANCES IN-VIVO INTERNALIZATION OF CHOLERA-TOXIN AND OF HORSERADISH-PEROXIDASE INTO RAT ENTEROCYTES

The in vivo effect of antisecretory factor (ASF, derived from pig plas ma) on the ability of cholera toxin (CT) and of horseradish peroxidase (HRP) to bind to and penetrate into epithelial cells of the rat small intestine was evaluated in the absence of anesthetics. The potencey o f intravenously administrated ASF was demonstrated by some 70% inhibit ion of CT-induced secretion in ligated small intestinal loops. Using i mmunohistochemical methods for visualization, we found ASF to enhance internalization of both CT and HRP after 30 to 60 min of challenge, wi thout interfering with the initial binding to the enterocyte brush bor der region. The internalization process started in the upper 2/3 of th e villus region. After 5 h, no CT or HRP could be seen bound to the en terocytes. The results suggest that ASF might enhance small intestinal absorption.