Glycogen and Water Storage

MacKay and Bergman 1 stated that in rabbits there is a tendency for water to be stored in direct proportion to glycogen storage in the liver. The same authors 2 found that in young albino rats, on the average 3.8 gm. of water are stored with each gram of glycogen. That there is a relationship between glycogen and water storage is denied by Puckett, 3 Holmquist, 4 and Bridge. 5

In view of the difference of opinion noted above, the authors decided to study the question. Adult rats (in most cases) of the Long-Evans strain were used. All the animals were kept on the McCollum Stock Diet I (whole wheat ground, 67.5%, casein 15%, whole milk powder 10%, butter fat 5.2%, calcium carbonate 1.5%, and sodium chloride 0.8%). The rats were killed by decapitation; the blood sugar was studied by the Shaffer-Somogyi method, the glycogen in a portion of the liver by the method described previously, 6 and the water content in the remaining portion of the liver by drying in an oven to constant weight at 105°C.

In the first study 48 adult and 6 young rats were used. They were not fasted, but allowed the stock diet ad libitum until the time of killing. The results for the males and females are combined, and shown in Table I.

The relationship between glycogen and water content was tested by the determination of the correlation coefficient. When the percentage of glycogen and the percentage of water are used in the calculations, the correlation coefficient is +.202 ± .088, which would indicate a lack of correlation. However, when the absolute values, as glycogen per liver and water per liver, are used in the calculations, the correlation coefficient is +.745 ± .041.