ABSTRACT
A number of luminal factors are obvious potential mediators of effects on brush border membranes. These include pancreatic enzymes, bacterial enzymes, bile acids, and other surface active agents such as lysolecithin. Disaccharidases and many other surface proteins are located on villus cells and not in the crypts. Cell migration becomes a factor in assessing brush border turnover. The chapter discusses the influences on cell migration rates. Pancreatic enzymes have been shown to play a role in physiological alterations of brush border disaccharidase activity. The role of bacterial proteases as modifiers of brush border enzymes has been studied somewhat less intensively, probably because of the lack of availability of the appropriate proteases. G. G. Forstner and co-workers first suggested that in the surgical stagnant loop syndrome of rats, bacterial proteases produced a fall in disaccharidase acitivity. The enzyme responsible was not identified, but was inhibited by elastase inhibitors.
