scholarly journals Intestinal alkaline phosphatase regulates protective surface microclimate pH in rat duodenum

2009 ◽  
Vol 587 (14) ◽  
pp. 3651-3663 ◽  
Author(s):  
Misa Mizumori ◽  
Maggie Ham ◽  
Paul H. Guth ◽  
Eli Engel ◽  
Jonathan D. Kaunitz ◽  
...  
Keyword(s):  
Alkaline Phosphatase ◽  
Intestinal Alkaline Phosphatase ◽  
Microclimate Ph ◽  
Rat Duodenum

Duodenal brush border intestinal alkaline phosphatase activity affects bicarbonate secretion in rats

2007 ◽  
Vol 293 (6) ◽  
pp. G1223-G1233 ◽  
Author(s):  
Yasutada Akiba ◽  
Misa Mizumori ◽  
Paul H. Guth ◽  
Eli Engel ◽  
Jonathan D. Kaunitz
Keyword(s):  
Alkaline Phosphatase ◽  
Brush Border ◽  
Intestinal Alkaline Phosphatase ◽  
Glycerol Phosphate ◽  
Secretory Rate ◽  
Rat Duodenum ◽  
Ph Stat ◽  
Cystic Fibrosis Transmembrane

We hypothesized that duodenal HCO3− secretion alkalinizes the microclimate surrounding intestinal alkaline phosphatase (IAP), increasing its activity. We measured AP activity in rat duodenum in situ in frozen sections with the fluorogenic substrate ELF-97 phosphate and measured duodenal HCO3− secretion with a pH-stat in perfused duodenal loops. We examined the effects of the IAP inhibitors l-cysteine or l-phenylalanine (0.1–10 mM) or the tissue nonspecific AP inhibitor levamisole (0.1–10 mM) on AP activity in vitro and on acid-induced duodenal HCO3− secretion in vivo. AP activity was the highest in the duodenal brush border, decreasing longitudinally to the large intestine with no activity in stomach. Villous surface AP activity measured in vivo was enhanced by PGE2 intravenously and inhibited by luminal l-cysteine. Furthermore, incubation with a pH 2.2 solution reduced AP activity in vivo, whereas pretreatment with the cystic fibrosis transmembrane regulator (CFTR) inhibitor CFTRinh-172 abolished AP activity at pH 2.2. l-Cysteine and l-phenylalanine enhanced acid-augmented duodenal HCO3− secretion. The nonselective P2 receptor antagonist suramin (1 mM) reduced acid-induced HCO3− secretion. Moreover, l-cysteine or the competitive AP inhibitor glycerol phosphate (10 mM) increased HCO3− secretion, inhibited by suramin. In conclusion, enhancement of the duodenal HCO3− secretory rate increased AP activity, whereas inhibition of AP activity increased the HCO3− secretory rate. These data support our hypothesis that HCO3− secretion increases AP activity by increasing local pH at its catalytic site and that AP hydrolyzes endogenous luminal phosphates, presumably ATP, which increases HCO3− secretion via activation of P2 receptors.

scholarly journals Influence of Secretin and Cholecystokinin on Intestinal Alkaline Phosphatase Secretion

1973 ◽  
Vol 64 (4) ◽  
pp. 599-602 ◽  
Author(s):  
Walter P. Dyck ◽  
George A. Martin ◽  
Charles R. Ratliff
Keyword(s):  
Alkaline Phosphatase ◽  
Intestinal Alkaline Phosphatase

scholarly journals Characterization and comparison of soluble and membranous forms of intestinal alkaline phosphatase from the suckling rat.

1981 ◽  
Vol 256 (11) ◽  
pp. 5620-5626
Author(s):  
S.T. Yedlin ◽  
G.P. Young ◽  
B. Seetharam ◽  
S. Seetharam ◽  
D.H. Alpers
Keyword(s):  
Alkaline Phosphatase ◽  
Intestinal Alkaline Phosphatase

scholarly journals Sequence and characterization of the human intestinal alkaline phosphatase gene.

1988 ◽  
Vol 263 (24) ◽  
pp. 12011-12019 ◽  
Author(s):  
P S Henthorn ◽  
M Raducha ◽  
T Kadesch ◽  
M J Weiss ◽  
H Harris
Keyword(s):  
Alkaline Phosphatase ◽  
Intestinal Alkaline Phosphatase
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