title: Pancreatic sympathetic nerves contribute to increased glucagon secretion during severe hypoglycemia in dogs.
abstract: To determine if pancreatic sympathetic nerves can contribute to increased glucagon secretion during hypoglycemia, plasma glucagon and pancreatic glucagon secretion in situ were measured before and during insulin-induced hypoglycemia in three groups of halothane-anesthetized dogs. All dogs were bilaterally vagotomized to eliminate the input from pancreatic parasympathetic nerves. One group of dogs received only vagotomy (VAGX). A second group was vagotomized and adrenalectomized (VAGX + ADX). A third group received vagotomy, adrenalectomy, plus surgical denervation of the pancreas (VAGX + ADX + NERVX) to prevent activation of pancreatic sympathetic nerves. In dogs with VAGX only, hypoglycemia increased plasma epinephrine (Epi), pancreatic norepinephrine (NE) output (+320 +/- 140 pg/min, P < 0.05), arterial plasma glucagon (+28 +/- 12 pg/ml, P < 0.01), and pancreatic glucagon output (+1,470 +/- 370 pg/min, P < 0.01). The addition of ADX eliminated the increase of Epi but did not increase pancreatic NE output (+370 +/- 190 pg/min, P < 0.025), arterial plasma glucagon (+20 +/- 5 pg/ml, P < 0.01), or pancreatic glucagon output (+810 +/- 200 pg/min, P < 0.01). In contrast, the addition of pancreatic denervation eliminated the increase of pancreatic NE output (-20 +/- 40 pg/min, P < 0.05 vs. VAGX), the arterial glucagon (+1 +/- 2 pg/ml, P < 0.01 vs. VAGX), and pancreatic glucagon output responses (+210 +/- 280 pg/min, P < 0.025 vs. VAGX) to hypoglycemia. Thus activation of pancreatic sympathetic nerves can contribute to the increased glucagon secretion during severe insulin-induced hypoglycemia in dogs.
authors.affiliation: Department of Anatomy, Physiology, and Cell Biology, School of Veterinary Medicine, University of California, Davis 95616, USA.
authors.forename: P J
authors.initials: PJ
authors.lastname: Havel
authors.forename: T O
authors.initials: TO
authors.lastname: Mundinger
authors.forename: G J
authors.initials: GJ
authors.lastname: Taborsky
mesh_terms: D000315:Adrenalectomy; D000818:Animals; D001158:Arteries; D001786:Blood Glucose / Q000032:analysis; D003714:Denervation; D004285:Dogs; D004837:Epinephrine / Q000097:blood; D005934:Glucagon / Q000097:blood / Q000378:metabolism*; D007003:Hypoglycemia / Q000378:metabolism*; D009638:Norepinephrine / Q000378:metabolism; D010179:Pancreas / Q000294:innervation* / Q000378:metabolism; D013564:Sympathetic Nervous System / Q000502:physiology*; D014628:Vagotomy
chemical_list: D001786:Blood Glucose; D005934:Glucagon; D009638:Norepinephrine; D004837:Epinephrine