Preliminary results were presented in part at the National Meeting of the American Federation for Clinical Research, San Francisco, April, 1981 and were published in abstract form (Clin. Res. 29:307A, 1981).
Bile Acid-Dependent Secretion of Alkaline Phosphatase in Rat Bile†
Article first published online: 8 OCT 2007
Copyright © 1982 American Association for the Study of Liver Diseases
Volume 2, Issue 4, pages 433S–439S, July/August 1982
How to Cite
Hatoff, D. E. and Hardison, W. G. M. (1982), Bile Acid-Dependent Secretion of Alkaline Phosphatase in Rat Bile. Hepatology, 2: 433S–439S. doi: 10.1002/hep.1840020407
- Issue published online: 8 OCT 2007
- Article first published online: 8 OCT 2007
- Manuscript Accepted: 2 MAR 1982
- Manuscript Received: 28 AUG 1981
- Veterans Administration
- National Institutes of Health
The role of bile acids in the biliary secretion of alkaline phosphatase was studied. Rats with external bile fistulae were drained for 4 hr. After 2 hr, bile acid secretion fell progressively. Alkaline phosphatase secretion also decreased progressively during the period of drainage, suggesting that secretion of the two components was related. Each rat was then given an i.v. infusion of the taurine conjugate of either cholate, chenodeoxycholate, or ursodeoxycholate. Alkaline phosphatase secretion increased in a dose-dependent manner as bile acid secretion was varied over and beyond the physiologic range. Each bile acid affected alkaline phosphatase secretion differently: given at 0.5 /imoles per min per 100 gm, tauroursodeoxycholate caused a 3-fold, taurocholate a 14-fold, and taurochenodeoxycholate a 75-fold increase in enzyme secretion. To determine if these findings might represent elution of canalicular enzyme by bile acids, isolated liver surface membranes were incubated with the bile acids. Like the findings in vivo, taurochenodeoxycholate was strongest and tauroursodeoxycholate weakest in removing alkaline phosphatase from the membrane. Differential centrifugation of liver surface membranes after exposure to bile acids and ultracentrifugation of bile showed that more than half of the enzyme released by the action of bile acids did not sediment at 100,000 g and, thus, could be considered soluble. These results document bile acid-dependent secretion of alkaline phosphatase in rat bile and suggest that the process involves solubilization of both membrane fragments and free enzyme from membranes lining the biliary space.