Absence of alkaline phosphatase-linked inorganic phosphate transport in the chick jejunum.

The role of non-specific alkaline phosphatase-linked inorganic phosphate (Pi) transport in the chick jejunum was investigated by using the everted gut sac technique. The highest intensity of transport was observed for free Pi. The maximal transport rate was considerably reduced when beta-glycerophosphate was used as a single source of phosphorus. These results suggested absence of the alkaline phosphatase-linked transport system for inorganic phosphate in the epithelium of the chick jejunum. Studies of Mg effect on Pi absorption as well as examination of temporal changes in Pi transport rate and beta-glycerophosphate hydrolysis rate by intestinal brush border alkaline phosphatase gave further backing to this suggestion.