REACTIONS OF THE TWO TYPES OF A CELLS IN THE ISLETS OF LANGERHANS AFTER ADMINISTRATION OF GLUCAGON

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Abstract
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 A1 cells decreased by 4.4%, a more pronounced and highly significant nuclear atrophy was noted in the A2 cells. After 5 days'' treatment with glucagon the nuclear size ratio A2/B was reduced from 0.94 to 0.91 (t = 2.69; P < 0.02). As a consequence of the regressive changes in the A2 cells the nuclei of these cells were smaller than those of the A1 cells in all 10 glucagon treated rats analysed. The finding of a considerable nuclear atrophy of the A2 cells lends support to the hypothesis that these cells produce glucagon.