Sugar Utilization in Hypophysectomized Rabbits

Abstract

The fact that serious hypoglycemia may develop in hypophysectomized rabbits and dogs is well known. 1 3-4 In preliminary experiments it was found that glucose must be administered to fasted hypophysectomized rabbits to prevent hypoglycemic convulsions and death. The animal requires large amounts of sugar even when the blood sugar level is low. The work reported here was concerned with the measurement of this requirement. The aim was to determine the minimum amount of glucose necessary to maintain a proper blood sugar level in fasted hypophysectomized rabbits. After a 3-day fast the pituitary was removed by an oral approach (Cope's 5 ) modification of White's method. 2

Frequent blood sugar estimations were carried out after the hypophysectomy. When the level had fallen to 80 mg. % or lower sufficient 10% glucose was given intravenously every hour thereafter to keep it from going lower. The rate of injection was adjusted according to whether the previous blood sugar had indicated the level was rising or falling.

The interval between time of operation and time when the blood sugar began to drop varied in different rabbits from 11 to 32 hours. The amount of glucose required increased during the first 5 to 8 hours thereafter, by which time a maximum requirement was attained. There was little increase above this. Glucose was given in some cases by continuous intravenous injection. In a given animal, the amount required was the same whether the glucose was given at one hour intervals or by continuous injection. Urinary determinations for sugar were uniformly negative. The amounts of glucose which had to be injected during the period of maximum need is recorded in grams per kilo body weight per hour in Table I.