title: Cytochemical studies on the localization of alkaline phosphatase and HCO-3-activated adenosine triphosphatase in the brush border membrane of rat duodenal enterocytes.
abstract: Cytochemical techniques were used to demonstrate, with appropriate controls, alkaline phosphatase and HCO-3-activated adenosine triphosphatase (ATPase) in rat duodenal brush border microvillus membranes. Intense activity of ecto-alkaline phosphatase activity was demonstrated with 2-glycerophosphate as substrate. Although biochemical assays suggested that L-phenylalanine inhibited both alkaline phosphatase and HCO-3-activated ATPase, cytochemical studies indicated that there was marked inhibition of alkaline phosphatase revealing a specific HCO-3-activated ATPase on the inner aspect of the microvillus membrane. While it is tempting to suggest that this HCO-3-activated ATPase is implicated in active bicarbonate secretion by the duodenum, decisive identification is not yet possible.
mesh_terms: D000251:Adenosine Triphosphatases / Q000032:analysis*; D000469:Alkaline Phosphatase / Q000032:analysis*; D000818:Animals; D027321:Anion Transport Proteins; D004386:Duodenum / Q000201:enzymology* / Q000648:ultrastructure; D005994:Glycerophosphates; D006651:Histocytochemistry; D008871:Microvilli / Q000201:enzymology; D051381:Rats
chemical_list: D027321:Anion Transport Proteins; D005994:Glycerophosphates; D000469:Alkaline Phosphatase; D000251:Adenosine Triphosphatases; C031652:anion-sensitive ATPases