AJP - Regulatory, Integrative and Comparative Physiology, Vol 254, Issue 3 518-R523, Copyright © 1988 by American Physiological Society
Adrenergic modulation of pancreatic glucagon and insulin secretion in sheep
S. Oda, A. Hagino, A. Ohneda, Y. Sasaki and T. Tsuda
Laboratory of Animal Physiology, Faculty of Agriculture, Tohoku University, Sendai, Japan.
The effect of intravenous infusion of epinephrine, either alone or together
with various doses of phentolamine or propranolol, on the secretion of both
glucagon and insulin was determined in six sheep. Intravenous infusion of
epinephrine alone caused increases in plasma glucagon and glucose
concentrations and produced a slight but significant decrease in plasma
insulin concentration. The concomitant infusion of propranolol and
epinephrine augmented glucagon release and inhibited insulin secretion.
Combined propranolol plus epinephrine infusion also caused a marked
hyperglycemia. The concomitant infusion of phentolamine and epinephrine
produced slight inhibition of glucagon secretion and markedly promoted
insulin secretion. Epinephrine-induced hyperglycemia was eliminated by
phentolamine infusion. The effects of isoproterenol infusion on plasma
glucagon, insulin, and glucose concentrations were similar to that caused
by the concomitant infusion of phentolamine and epinephrine. The effects of
isoproterenol were abolished by the infusion of propranolol. It is
concluded that an alpha-receptor mechanism is the most important component
of adrenergic modulation of pancreatic glucagon secretion, whereas
beta-receptor activation stimulates and alpha-receptor activation inhibits
insulin secretion in sheep.
