On the Carbohydrate Metabolism of Adrenalectomized Rats.

Abstract

It is known that adrenalectomized cats and dogs frequently have a blood sugar concentration below normal. These two species survive the operation only a short time, and the animals generally refuse to eat some time before death. It was, therefore, not certain whether the low blood sugar was a symptom of adrenal insufficiency, or whether it was due to the imminent death of the animals, since a low blood sugar before death from other causes is not uncommon. On the other hand, a larger percentage of adrenalectomized rats survive the operation for a long time. About 20 per cent of our operated animals 10 to 14 days after removal of both glands had maintained their original body weight or even surpassed it. Incidental to other work, it was noted that these rats showed a low blood sugar when they were fasted for 24 hours. Six rats showed a blood sugar ranging from 53 to 79 mg. per cent. A simultaneous analysis of the liver and the rest of the body tissues revealed that there was practically no liver glycogen present, while the rest of the body tissues, chiefly the muscles, showed a normal glycogen content. The absence of liver glycogen explains the low blood sugar of these animals, since the liver glycogen is the only source for blood sugar. There is good evidence that the muscle glycogen does not participate in blood sugar regulation. When normal rats are fasted for 24 hours, the blood sugar rarely falls below 0.1 per cent and there is from 0.4 to 1.0 per cent liver glycogen present. Even after a 48 hour fast there is sufficient liver glycogen present to maintain a normal blood sugar concentration. The lack of liver glycogen in fasting adrenalectomized rats may have two causes.