Bile salt absorption in the irradiated rat

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Abstract
Measurements of radioactivity in bile secreted by bile duct-cannulated rats after intraluminal injection of the labeled bile salt indicated bile salt absorption rates in the duodenum, ileum, and large intestine in the ratio of 1:30:2. Three days after exposure of the abdomen to 1,000 or 1,500 R of X-irradiation, absorption from the ileum was decreased by 14 and 53%, respectively. Five days after exposure to 1,500 R, absorption from the ileum was decreased by 70%. The radiomimetic nitrogen mustard, HN2, also decreased absorption. This was shown to be a radiation-induced absorption defect which probably resulted in increased excretion of bile salts, rather than an impaired secretion of bile by the liver, by injecting labeled bile salts intravenously or parenterally. At 4 days after 1,500 R and 1 day after intravenous injection of C14-labeled cholic acid, the accumulation of labeled bile salt in the lower bowel was almost twice the unirradiated value. The level of radioactivity secreted in the bile at that time was one-half control value and that present in the small intestine only one-sixth the unirradiated level, suggesting a dilution of the labeled bile salt as a result of de novo synthesis and a substantial accumulation of bile salts in the lower small intestine and large bowel.