Reactions of the Two Types of a Cells in the Islets of Langerhans After Administration of Glucagon

Repeated subcutaneous injections of crystalline glucagon resulted in a rapid loss of body weight in 5 weeks old rats allowed free access to food. In spite of the large glucagon doses employed (0.3–0.4 mg per rat a day) there was no glycosuria or morphological evidence of an increased insulin secretion from the B cells in the islets of Langerhans. While the nuclear areas of both the islet B and A 1 cells decreased by 4.4%, a more pronounced and highly significant nuclear atrophy was noted in the A 2 cells. After 5 days' treatment with glucagon the nuclear size ratio A 2 /B was reduced from 0.94 to 0.91 ( t = 2.69; P < 0.02). As a consequence of the regressive changes in the A 2 cells the nuclei of these cells were smaller than those of the A 1 cells in all 10 glucagon treated rats analysed. The finding of a considerable nuclear atrophy of the A 2 cells lends support to the hypothesis that these cells produce glucagon.