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 was stimulated by 25 mM arginine. This stimulation was only slightly increased by pregnancy and lactation. Insulin secretion increased, when the glucose concentration was raised from 2.5 to 5.0 mM, especially in pregnant islets and was also stimulated by arginine. The arginine stimulated insulin release was greatly augmented during late pregnancy and lactation. Islet content did not reflect the changes in secretion: glucagon content increased in the course of pregnancy and lactation, while insulin content was increased during late pregnancy, but not during lactation. It is concluded that, unlike insulin, glucagon is only marginally involved in the increase in anabolism during pregnancy and lactation.