ABSTRACT
Analysis of subcellular localization of pig intestinal DAO by confocal laser scanning uorescence microscopy suggests that the enzyme is present in vesicular structures that form a network near the plasma membranes of cells (Schwelberger et al., 1998). The villus cells, predominantly those from the middle and apex (but not crypt cells), contain intestinal DAO. This implies that any event leading to a damage or loss of villus structure will exert great impact on enzyme levels in the intestinal mucosa. DAO is not associated with the brush border and is exported from parenchymal cells to vascular binding sites of intestinal microvasculature where it is released by heparin. The low basal plasma level of DAO is considered to be of the intestinal origin (Shakir et al., 1977; Robinson-White et al., 1985). Intestinal DAO does not accept
monoamines but degrades short-chain aliphatic diamines, putrescine, cadaverine, histamine, N(τ)-methylhistamine, and spermidine (Bieganski et al., 1983).
