Effects of pancreatic noradrenaline infusion on basal and stimulated islet hormone secretion in the dog

Abstract

We investigated the direct pancreatic effects of noradrenaline in vivo on the secretion of insulin, glucagon, and somatostatin from the in situ pancreas in halothane-anaesthetized dogs. Noradrenaline was infused into the superior pancreatic artery at 12 ng min-1, a rate that did not alter systemic glucose or noradrenaline levels nor heart rate or blood pressure. This pancreatic infusion of noradrenaline did not affect the basal pancreatic output of insulin, yet did markedly inhibit arginine-stimulated insulin secretion. The acute insulin response (AIR) to an intravenous injection of arginine (2.5 g), which was 4293 +/- 1260 microM min-1 under control conditions, was reduced to 1054 +/- 396 microU min-1 by noradrenaline (P less than 0.01). Noradrenaline increased basal pancreatic glucagon output from 321 +/- 130 pg min-1 to 876 +/- 309 pg min-1 after 20 min of infusion (P less than 0.05) and the acute glucagon response (AGR) to arginine, being 1033 +/- 203 pg min-1 under control conditions and 1746 +/- 249 pg min-1 during noradrenaline infusion (P less than 0.05). The basal output of somatostatin did not change during noradrenaline infusion, but arginine-stimulated somatostatin secretion was impaired. The acute somatostatin response (ASLIR) to arginine was 473 +/- 124 fmol min-1 under control conditions and was decreased to 140 +/- 80 fmol min-1 by noradrenaline (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)