Studies on the mechanism of action of calciferol III. Vitamin D-mediated increase of intestinal brush border alkaline phosphatase activity

摘要: Abstract 1. Experiments were carried out to elucidate some of the biochemical consequences vitamin D administration, in vivo, its target organ, intestinal mucosa. Oral administration 500 I.U. D3 (cholecalciferol) D-deficient chicks causes level alkaline phosphatase (orthophosphoric monoester phosphohydrolase, EC 3.1.3.1) mucosal homogenates increase 2–3-fold. The increased activity is maximal 60 h after vitamin. 2. phosphatase(s) both and D-treated localized exclusively brush border or microvilli fraction, site many absorption activities. Also levels Ca2+-stimulated ATPase (ATP 3.6.1.3) are elevated administration; however, treatment no change investase (δ- d -fructofuranoside fructohydrolase, 3.2.1.26) other related disaccharidases which fraction. 3. rise mediated by can be prevented vivo cycloheximide. This suggests that induces de novo synthesis this enzyme. 4. simultaneous time-course appearance (a) (b) rate transport calcium, measured across intact segments ileal tissue oral a functional involvement D-mediated calcium transport.