AJP - Gastrointestinal and Liver Physiology, Vol 250, Issue 2 248-G251, Copyright © 1986 by American Physiological Society
Effects of taurodeoxycholate on in vivo water and solute transport in rat jejunum in absence and presence of calcium
H. V. Ammon, D. S. Cho, R. L. Loeffler and K. L. Reetz
Bile acids and fatty acids enhance the permeability of brush-border
membrane vesicles for calcium. It has been postulated that increased influx
of calcium into the enterocyte might be responsible for the fluid secretion
induced by dihydroxy bile acids and fatty acids. During in vivo perfusion
studies of the rat jejunum, 15 mM taurodeoxycholate induced secretion of
electrolytes and water (P less than 0.001), reduced glucose absorption (P
less than 0.001), and enhanced the absorption of mannitol (P less than
0.0125) and calcium (P less than 0.001). Calcium absorption continued to be
enhanced during perfusion of a CaCl2-containing solution following the
perfusion with taurodeoxycholate (P less than 0.05). In view of the
previously demonstrated enhanced permeability of the apical brush-border
membrane in the presence of bile acids, it is very likely that some calcium
enters the enterocyte along the steep concentration gradient in the
presence of taurodeoxycholate. In spite of enhanced calcium absorption, 15
mM CaCl2 had no effect on control absorption rates or on fluid secretion
induced by taurodeoxycholate. The data indicate that the effects of bile
acids on intestinal transport are not mediated by an influx of calcium into
the enterocyte.
