Purpose: To determine the effect of mixed neutron and gamma-irradiation on the bile acid pool, which may be a key factor in radiation-induced diarrhoea.
Materials and methods: The bile duct of pigs was catheterized to derive bile over several experimental weeks, both before and after a 5.9 Gy neutron and gamma-irradiation. After measurement of the volume and sampling, bile was returned to the pig via a duodenal catheter. Samples of bile were analysed by HPLC for their individual and total bile acid content. Blood samples were also collected for total bile acid determination.
Results: Bile flow was significantly decreased during the first 24h and after the fifth day post-irradiation. Whereas total bile acid concentration in bile was not altered, profiles of individual bile acids were significantly altered as early as the first post-irradiation day. Such modifications in these profiles resulted in a change of the properties of the bile acid pool. An increased proportion of dihydroxylated bile acids known to be more deleterious for the intestine was observed.
Conclusions: Neutron and gamma-irradiation leads to modifications of bile acid profiles, which may partly explain radiation-induced diarrhoea by a coherent physiopathological mechanism.