ARGININE STIMULATED GLUCAGON AND INSULIN-SECRETION BY ISLETS OF LANGERHANS OF PREGNANT AND LACTATING RATS

Glucagon secretion by isolated pancreatic rat islets was not affected by an increase of the glucose concentration from 2.5 to 5.0 mM, but wa s stimulated by 25 mM arginine. This stimulation was only slightly inc reased by pregnancy and lactation. Insulin secretion increased, when t he glucose concentration was raised from 2.5 to 5.0 mM, especially in pregnant islets and was also stimulated by arginine. The arginine stim ulated insulin release was greatly augmented during late pregnancy and lactation. Islet content did not reflect the changes in secretion: gl ucagon content increased in the course of pregnancy and lactation, whi le insulin content was increased during late pregnancy, but not during lactation. It is concluded that, unlike insulin, glucagon is only mar ginally involved in the increase in anabolism during pregnancy and lac tation.