Intestinal absorption of bile salts: immature development in the neonate

The intestinal absorption of sodium taurocholate was studied in fetuses, neonates, infants, children, and adults. Absorption rates were measured in vitro in everted rings of jejunum and ileum. Mucosal accumulation of 3H-taurocholate against a concentration gradient was consistently demonstrated in rings of ileum from adults, children, and infants older than 8 months, whereas fetal and neonatal ileal mucosal concentrations were not significantly above those in the incubation medium after exposure of the mucosa to 0.003, 0.03, and 0.3 mM taurocholate. There were no significant differences in mucosal uptake of taurocholate by perinatal jejunal and ileal rings. Incubations of mucosa from older infants, children, and adults in 0.3 mM taurocholate exhibited saturation phenomena. It is concluded that the ileal mechanism for active transport of taurocholate is undeveloped in the fetus and newborn infant. It is probable that the enterohepatic circulation of bile salt during the perinatal period is limited to that fraction of bile salt absorbed passively. The results suggest that losses of bile salt from the immature intestine may contribute to the steatorrhea and so-called diarrhea of newborn infants.