[Small intestinal alkaline phosphatase activity and changes induced by cysteamine administration in fecal excretions of male Wistar rats].

Alkaline phosphatase (ALP) activity in fecal excretions was measured in male Wistar rats. Total daily ALP activity in fecal extracts was 133.1 +/- 21.2 mumoles/min per rat weighing approximately 150 g. We found that 63.7% of the fecal ALP activity was inhibited by 30 mM L-phenylalanine (L-Phe), a specific inhibitor for intestinal ALP. As body weight increased from 150 g to 300 g, total daily ALP activity in fecal extracts decreased rapidly to 33.7 +/- 6.08 mumoles/min/rat. However, the percentage of L-Phe-sensitive ALP to total enzyme activity was less variable (40-65%) in the growing rats. Cysteamine-HCl, an ulcerogenic drug, was injected subcutaneously to adult rats (300 g b. w) at a dosage of 400 mg/kg. b. w. Daily excretion of L-Phe-sensitive ALP in fecal extracts decreased to one-third 2 days after injection. Afterwards, a steep and transient increase in the enzyme activity was detected in fecal extracts between days 4 and 7 after injection. ALP activity in fecal excretions may be a clinical indicator of duodenal mucosal damage.