Intravenous Glucose Tolerance Test In Hypophysectomized Rats

¹ From the Laboratory of Nutrition and Endocrinology, National Institute of Arthritis and Metabolic Diseases, National Institutes of Health, Bethesda, Maryland

Intravenous glucose tolerance tests were performed on normal and hypophysectomized rats that had been allowed to eat at will or were fed a constant amount by tube. The rates of removal of excess blood glucose (k) were calculated. The k values for unoperated rats were the same regardless of the means of administration of food. The rate of removal of excess glucose was decreased in ad libitum-fed but not in tube-fed hypophysectomized rats. In the operated animals the value of k was not constant; it increased with time after administration of glucose load. Increasing the duration of fasting of operated tube-fed rats decreased the k; prior oral administration of glucose to hypophysectomized rats fed ad libitum increased the k. The lability of the intravenous glucose tolerance test in hypophysectomized rats is stressed.