Contents and implications of ammonia human and canine bile

The quantification and physiological significance of ammonia in human and canine bile has not been clearly documented or analyzed previously. Bile from the gallbladder, common hepatic duct, and from T-tubes obtained from patients undergoing cholecystectomy and choledochotomy. Similar samples were obtained in 6 dogs by cannulation of their hepatic duct and various blood vessels. Simultaneous blood and bile samples were obtained at 15-min intervals before during, and after an exogenous load of ammonia, given intravenously. Ammonia levels were measured in all samples. Ammonia was measurable by conventional methods in human and canine bile. In both species the gallbladder bile contained at least twice as much ammonia as bile from the common hepatic duct. After an exogenous ammonia load, the levels of ammonia in canine bile increased in similar patterns, but in lesser magnitude than the ammonia levels measured at several sites in the circulation. The findings document that the bile contains ammonia in different quantities and suggest that bile could be an additional pathway for the removal of ammonia by the liver, in addition to the urea cycle. The loss of the biliary pathway for ammonia excretion could contribute to the pathophysiology of the signs and symptoms attributed to hyperammoniemia occurring in human beings and dogs with decreased hepatic function.