Short term and direct influence of oestradiol on glucagon secretion stimulated by arginine.

Long-term oestrogen treatments disturb the endocrine pancreas, with associated hypoglucagonaemia and hyperinsulinism. Short-term influences of oestradiol (4 h-8 h) were tested in vivo, and direct effects were studied in vitro with pieces of pancreas or islets of Langerhans. Both models showed a direct and dose-dependent inhibitory effect of oestradiol on the arginine-stimulated secretion of glucagon, related to the short-term hypoglucagonaemia. However, this direct negative effect of oestradiol on A cells occurred in spite of any influence, either on insulinaemia or on the arginine-induced insulin secretion. This supports the hypothesis of a possibility of A cells to function independently of B cells.