title: Effect and mechanism of vagal nerve stimulation on somatostatin secretion in dogs.
abstract: To investigate the effect of vagal nerve stimulation on the release of pancreatic somatostatin, we electrically stimulated (10 Hz, 5 ms, 13.5 mA, and 10 min) the thoracic vagi just below the heart in halothane anesthetized dogs (n = 15). The stimulation increased the pancreatic output of somatostatinlike immunoreactivity (SLI) (delta = +248 +/- 81 fmol/min, P less than 0.005; base-line levels = 455 +/- 150 fmol/min). min). Arterial plasma SLI levels increased as well (delta = +16 +/- 3 fmol/ml, P less than 0.001; base-line levels = 65 +/- 3 fmol/ml), reflecting stimulation of extrapancreatic SLI secretion. Significant vagal activation was verified by a fivefold increase of pancreatic output of pancreatic polypeptide (PP) (delta = +31.4 +/- 5.9 ng/min, P less than 0.001; base-line levels = 7.8 +/- 0.9 ng/min). Atropine pretreatment (n = 6) inhibited partially both the PP response (delta = +7.9 +/- 3.8 ng/min after atropine) and the pancreatic SLI response (delta = +92 +/- 29 fmol/min) to vagal nerve stimulation. However, atropine pretreatment did not modify the arterial SLI response (delta = +20 +/- 7 fmol/ml). Hexamethonium pretreatment (n = 9) completely abolished all three responses. We conclude that 1) electrical stimulation of the vagus stimulates pancreatic SLI, extrapancreatic SLI, and PP release in vivo in the dog; 2) both muscarinic and nonmuscarinic mechanisms mediate the PP and pancreatic SLI responses; 3) a nonmuscarinic mechanism mediates the extrapancreatic SLI response; and 4) all three responses are mediated via ganglionic nicotinic receptors.
authors.forename: B
authors.initials: B
authors.lastname: Ahrén
authors.forename: T L
authors.initials: TL
authors.lastname: Paquette
authors.forename: G J
authors.initials: GJ
authors.lastname: Taborsky
mesh_terms: D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001696:Biomechanical Phenomena; D004285:Dogs; D004558:Electric Stimulation; D006329:Heart Conduction System; D018738:Hexamethonium; D006584:Hexamethonium Compounds / Q000494:pharmacology; D009333:Neck / Q000294:innervation; D010179:Pancreas / Q000378:metabolism; D010191:Pancreatic Polypeptide / Q000378:metabolism; D013004:Somatostatin / Q000378:metabolism*; D013909:Thorax / Q000294:innervation; D014630:Vagus Nerve / Q000502:physiology*
chemical_list: D006584:Hexamethonium Compounds; D018738:Hexamethonium; D013004:Somatostatin; D010191:Pancreatic Polypeptide; D001285:Atropine