Bile-salt inhibition of sodium ion-coupled D-glucose and L-alanine accumulation by brush-border-membrane vesicles from hamster jejunum.
The effects of bile salts on Na+-coupled accumulation of D-glucose and L-alanine by brush-border-membrane vesicles isolated from hamster jejunum were investigated. The approximate percentage inhibition of Na+-coupled D-glucose accumulation produced by various bile salts at a concentration of 1 mM were: deoxycholate and chenodeoxycholate, 60%; glycine and taurine conjugates of deoxycholate and chenodeoxycholate, 40--50%; lithocholate, 45%; cholate and its glycine and taurine conjugates, less than 10%. Inhibition of Na+-coupled accumulation of D-glucose was rapid, reversible and not due to dissolution of the vesicles. Na+-coupled accumulation of L-alanine was also inhibited by deoxycholate. Deoxycholate but not cholate enhanced (1) the rate of Na+ influx, (2) the rate of influx of D-glucose and L-alanine in the absence of a Na+ gradient and (3) the rate of efflux of D-glucose and L-alanine from vesicles preloaded with this sugar or amino acid. Deoxycholate-stimulated efflux of D-glucose was not blocked by phlorizin, which completely prevented efflux in the absence of this bile salt. These results suggest that selected bile salts inhibit Na+-coupled accumulation of D-glucose and L-alanine by enhancing the rate of dissipation of the Na+ gradient required for substrate accumulation. In addition, bile salts may also decrease D-glucose and L-alanine accumulation by increasing the rate of efflux of these substrates across the brush-border plasma membrane.
D000409:Alanine / Q000378:metabolism*; D000818:Animals; D001647:Bile Acids and Salts / Q000494:pharmacology*; D002462:Cell Membrane / Q000378:metabolism*; D002463:Cell Membrane Permeability / Q000187:drug effects; D006224:Cricetinae; D005947:Glucose / Q000378:metabolism*; D066298:In Vitro Techniques; D007408:Intestinal Absorption / Q000187:drug effects; D007583:Jejunum / Q000187:drug effects / Q000378:metabolism*; D008871:Microvilli / Q000187:drug effects / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism*
D001647:Bile Acids and Salts; D012964:Sodium; D005947:Glucose; D000409:Alanine