A Method for Interval Determinations of Liver Glycogen in the Same Dog.

In most experiments heretofore described for the study of changes in liver glycogen, a series of animals are used, one of which is sacrificed at the end of a given period. Cori 1 has described a method of obtaining several samples of liver from the same animal for the determination of liver glycogen. The advantage of repeated observations in the same animal is that the individual variations in liver glycogen between animals of the same species are avoided. In normal dogs, kept and fed under uniform conditions, we have found this to be from 1.3% to 7.2%. Varela, Duomarco and Munilla 2 found it to be from 0.74% to 4.68%. Similar differences are found in other animals.

To carry out repeated determinations of liver glycogen at stated intervals on the same animal, it seemed necessary first to bring a part of the liver to the body surface, where pieces could be excised. This is done as follows: Intra-tracheal anesthesia is given with the Erlanger positive pressure apparatus and through an incision on the right side, parallel and about 5 cm. anterior to the spine, the 4 lower ribs are then removed. The pleura and diaphragm are next opened in the same axis. The corresponding cut edges of diaphragm and pleura are sutured to each other, thus closing the pleural cavity. The thin attachments of the liver are then cut, allowing mobilization of the 2 lateral lobes or more. Any other procedure on other abdominal organs can be carried out at the same time, through the same incision, such as ligation of the bile ducts, removal of the pancreas, production of intestinal obstruction, etc. The liver is brought to the surface more by pushing in the collapsed chest wall than by traction.