Effects of Bile Salts on Glucose Metabolism by Slices of Hamster Small Intestine*

Abstract

Bile salts are known to be essential for the effective absorption of fat from the intestinal tract (1). They have been shown to stimulate the action of pancreatic lipase (2) and have an important emulsifying action on water-insoluble dietary triglycerides that is probably related to their ability to form micelles with fatty acids and monoglycerides (3). In addition to their role in triglyceride absorption, bile salts also appear to be essential in the absorption and esterification of vitamin A (4) and cholesterol (5).In previous studies from this laboratory (6), it was shown that conjugated bile salts enhanced the esterification of palmitate-C14 to triglycerides and appeared to stimulate the incorporation of glucose-C14 into glyceride-glycerol. These observations suggested that in the intestinal mucosa, bile salts influence the metabolism not only of lipid, but also of carbohydrate. The present experiments were designed to investigate further the actions of conjugated and unconjugated bile salts on glucose metabolism. These studies have been carried out with slices of hamster small intestine. In addition, because of some disagreement in the literature concerning the utilization of glycerol in the intestine (7,8), the metabolism of glucose and glycerol by hamster intestinal mucosa has been compared. EXPERIMENTAL PROCEDUREMaterials. Male golden hamsters 1 weighing 100 to 120 g were used in all experiments. Glucose-1-Cl4 2 and glucose-6-Cl42 were checked for purity on Dowex columns. Batches of glucose-C14 with more than 0.5% im-

Utilization of Glycerol-C14 for Intestinal Glyceride Esterification: Studies in a Patient with Chyluria *

“…They confirm experiments in intact rats and in rat and hamster intestinal slice preparations (8,19) that also showed glycerol incorporation into chyle or mucosal lipids. Although less than 20%c of the lipid-glycerol excreted in the urine in 24 hours was labeled, in fractional urine collections as much as 60 and 41% were incorporated.…”

“…The counting solutions used for the lipid and water soluble fractions were prepared as described previously (19). Internal standards were used in all quenched samples.…”

“…This pathway would not have resulted in rearrangement of the C14-labeled glycerol. Glycerol metabolism by the intestinal mucosa has been observed in vitro (8,19) but in amounts much smaller than glucose.…”

Production of bile duct hyperplasia and gallstones by lithocholic acid.

“…We have previously reported that the pyrogenic activity of lithocholic acid in man is abolished by conjugation of the steroid with taurine but not with glycine (3). Isselbacher and his co-workers have described differences between the effects of taurine-and glycine-conjugated bile salts on glucose and fat metabolism in the small intestinal mucosa (30,31). Other substances, such as sulfate (26) and ornithine (32), which may be found conjugated with bile acids, might also therefore be expected to affect their physiological or pathological properties.…”

Rate-limiting steps in steady-state intestinal absorption of trioctanoin-l-14C

“…Hyamine solutions were counted with internal standards in 12 ml of toluene a scintillator (19). All other samples were counted in 15 ml of Bray's solution (20) $ Assume portal blood flow 600 ml/hr, hematocrit 40%.…”