Bile salt absorption in killifish intestine.
Bile salt absorption was examined in vitro using entire small intestines from the killifish Fundulus heteroclitus. Intestines were everted over a glass rod and incubated in solutions containing 10 nM to 20 mM bile salts. After rinsing and correcting for the adherent fluid space, uptake rates and bile salt concentrations in the tissue were determined. The distal intestine contained a Na+-dependent active transport system for bile salt uptake with an apparent Vmax for taurocholate and cholate of 1.4 and 2.3 nmol.min-1.mg dry wt-1 (Km = 117 and 357 microM), respectively. At low concentrations (10 nM to 500 microM), absorption occurred almost exclusively (greater than 84%) in the distal intestine. However, at concentrations of 1 mM and above, bile salt absorption in the middle and proximal regions equaled that in the distal intestine. Thus, although an active transport system makes the distal intestine more efficient in absorbing bile salts, passive absorption appears to account for a significant amount of bile salt uptake at concentrations above the critical micellar concentration. The presence of oleic acid did not significantly affect bile salt uptake.
Department of Microbiology, University of Georgia, Athens 30601.
R E
RE
Honkanen
J S
JS
Patton
D000818:Animals; D001647:Bile Acids and Salts / Q000378:metabolism*; D002793:Cholic Acids / Q000378:metabolism; D003532:Cyprinodontiformes / Q000502:physiology*; D005227:Fatty Acids / Q000378:metabolism; D066298:In Vitro Techniques; D007413:Intestinal Mucosa / Q000378:metabolism*; D007422:Intestines / Q000033:anatomy & histology; D007695:Killifishes / Q000502:physiology*; D012964:Sodium / Q000502:physiology; D013656:Taurocholic Acid / Q000378:metabolism
D001647:Bile Acids and Salts; D002793:Cholic Acids; D005227:Fatty Acids; D013656:Taurocholic Acid; D012964:Sodium