Influence of High-Phosphorus or High-Salt Feeding on Intestinal Alkaline Phosphatase Activity in Rats

Abstract

Alkaline phosphatase (ALP) hydrolyzes a variety of monophosphate esters into inorganic phosphoric acid and alcohol, but little is known about the physiological function of intestinal ALP. We investigated the influence of a high-phosphorus or high-salt dietary intake on intestinal alkaline phosphatase activity in rats. A total of 33 female Sprague-Dawley rats (6-weeks-old) were divided into four groups: control, 1.0% phosphorus (P 1.0%) group, 1.5% phosphorus (P 1.5%) group, and 1.0% sodium chloride (High Salt) groups. At 56 days after the beginning of the experiment, intestinal segments from the duodenum, jejunum, and ileum were obtained and used for enzyme assays. There was no significant difference in the levels of intestinal ALP activity between the high-phosphorus groups (P 1.0% and P 1.5% groups) and the control group. Interestingly, the levels of intestinal ALP activity in the duodenum and jejunum from the High Salt group were significantly lower than those from the control group (p<0.05 and p<0.01, respectively). These findings suggest that a high-salt dietary intake is one of the factors that decrease intestinal ALP activity. Further studies on the mechanism of the regulation of intestinal ALP activity would provide useful data on the physiological function of intestinal ALP.