A comparative study on the effects of different bile salts on mucosal ATPase and transport in the rat jejunum in vivo

Abstract

The effects of deoxycholate, taurocholate and cholate on transport and mucosal ATPase activity have been investigated in the rat jejunum in vivo using closed-loop and perfusion techniques. In the closed-loops, 5 mM deoxycholate selectively inactivated (Na + + K +)-ATPase , and net secretion of Na + induced by 2.5 mM deoxycholate was due to reduced lumen to plasma flux of the ion; deoxycholate (2.5 mM) produced marked inhibition of 3-O- methylglucose transport. Luminal disappearance rates of deoxycholate ( 60.5±2.9 % per g wet wt of gut ) greatly exceeded those of taurocholate (4.3±1.0). In the perfusion studies 1 mM deoxycholate induced net secretion of water, Na + and Cl −, and inhibited active glucose transport; concomitantly “total” ATPase, (Na + + K +)-ATPase , and Mg 2+-ATPase were inhibited. At higher concentrations (5 mM) deoxycholate stimulated Mg 2+-ATPase activity. Taurocholate and cholate at 1 mM had no effect on transport or (Na + + K +)-ATPase . Mucosal lactase, sucrase and maltase activities were not affected by 1 mM deoxycholate, taurocholate or cholate. These results suggest that deoxycholate inhibits sodium-coupled glucose transport by inhibition of (Na + + K +)-ATPase at the lateral and basal membranes of the epithelial cell, rather than from an effect at the brush-border membrane level.