STUDIES ON THE BLOOD GLUCOSE AND PANCREATIC ISLETS OF LIZARDS1

Abstract

Variations in blood glucose levels and in the cells of pancreatic islets under conditions of feeding, fasting, and administration of insulin and alloxan were studied in several species of lizards. The average fasting (7-28 days of fast) blood glucose was 94.5 mg %. Lizards in the absorptive state had blood glucose values ranging from 140.5 to 224.1 mg %. A minimal shocking dose of insulin is approximately 1000 units/kg. Larger doses of insulin (2000-10,500 units/kg) did not increase the degree of shock but prolonged its duration. Hypoglycemia was seen only during the first 20 minutes after insulin injection. After 30 minutes, fasting blood sugar levels were reattained, and after 90 minutes a compensatory hyperglycemia was invoked. Two weeks after alloxan administration (1.5 g/kg given in 5 divided doses) a hyperglycemia ranging from 145.5 to 209.2 mg % was seen coincident with destruction of beta cells. That the beta cells of lizard islets are concerned with the production of a hypoglycemic factor (insulin) is indicated by degranulation of these cells after glucose administration, partial atrophy after chronic insulin administration, and hyperglycemia subsequent to beta cell destruction by alloxan. That the alpha cells are concerned with the production of a hyperglycemic or fat metabolizing factor is indicated by degranulation of these cells during starvation, when blood glucose levels are sub-normal and fat is being mobilized, and by granular storage during the hyper-glycemia of alloxanization.