Abstract
In this laboratory the rat has been found to be a very useful experimental animal for purposes of studying bile function. Large numbers of animals may be used. Moreover, the rat is not particularly subject to infections, and special aseptic operative procedures do not need to be employed in preparing bile fistulas.
The internal bile fistula technique which has been found useful in dogs cannot be applied to the rat. This animal has no gall bladder nor a cystic duct, thus making a cholecystonephrostomy 1 impossible. The size of the structures involved prevents the making of a direct anastomosis between the bile duct and the kidney pelvis. The pancreatic ducts empty directly into the bile duct of the rat. Any bile fistula procedure must utilize only the upper portion of the bile duct so as to leave the pancreatic system intact.
Two bile fistula techniques in the rat have been described. In the first operation 2 an anastomosis between the bile duct and the lower colon is made with the aid of a small silver cannula. With proper care such animals live in good health for extended periods of time. The second operation 3 makes use of an artificial gall bladder which is inserted directly into the abdominal cavity. The original procedure has been modified by placing the glass bulb under the skin on the right side of the rat. The silver cannula which is inserted in the bile duct is connected to the glass vessel by means of a small parlodion tube. The second opening in the glass bulb communicates to the outside, thus permitting withdrawal of bile.
In the latter procedure rats live for only a short period of time when the bile is drained regularly. If the external opening is plugged to prevent loss of bile, the animals will survive for periods up to 6 weeks despite the extensive tissue destruction which results from the icteric condition. Administration of bile or of sodium chloride solution to the rat by stomach tube will prolong the life of the animal for a period of only 3 to 4 weeks. This, together with the danger of infection, makes the technique of no value when it is desired to prolong the experiments over periods of several months.
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