Differential neural regulation of circulating somatostatin-14 and somatostatin-28 in conscious dogs.
Somatostatin-like immunoreactivity (SLI) released into the circulation after nutrients or secretagogues is heterogeneous. To determine whether similar neural pathways regulate secretion of SLI molecular forms, circulating somatostatin-28 (S-28) and somatostatin-14 (S-14) responses to ingestion of a solid meal, intraduodenal perfusion of a liquid defined formula meal, and intravenous infusion of cholecystokinin octapeptide (CCK-OP, 250 pmol.kg-1.h-1) were measured in four conscious dogs with and without cryogenic blockade of the cervical vagus nerves. SLI was separated by gel-filtration chromatography of extracted, acidified plasma and quantified by radioimmunoassay. Basal plasma concentrations of S-28 were 4.1 +/- 0.6 fmol/ml and of S-14 were 3.8 +/- 0.4 fmol/ml. Ingestion of the solid meal increased plasma SLI threefold, and elevations of S-28 and S-14 were equivalent. After the intraduodenal liquid meal or infusion of CCK-OP, plasma SLI rose twofold, but increments of S-28 exceeded S-14, comprising approximately 70% of SLI released. Vagal blockade by cooling reversibly inhibited both the S-28 and S-14 responses to the solid meal, intraduodenal liquid meal, and CCK-OP. In contrast, atropine (50 micrograms/kg iv), given after solid food, intraduodenal nutrients, and CCK-OP, suppressed S-28 but further increased S-14 responses. Atropine did not, however, alter the suppression of S-14 and S-28 by vagal cooling.(ABSTRACT TRUNCATED AT 250 WORDS)
Greenberg
G R
GR
Department of Medicine, University of Toronto, Ontario, Canada.
D000818:Animals; D001285:Atropine / Q000494:pharmacology; D004285:Dogs; D004435:Eating / Q000502:physiology*; D005615:Freezing; D009407:Nerve Block; D011863:Radioimmunoassay / Q000379:methods; D012844:Sincalide / Q000494:pharmacology*; D013004:Somatostatin / Q000097:blood / Q000378:metabolism*; D053561:Somatostatin-28; D013997:Time Factors; D014630:Vagus Nerve / Q000502:physiology*
D013004:Somatostatin; D053561:Somatostatin-28; D001285:Atropine; D012844:Sincalide