Effects of peptide YY on pancreatic blood flow and oxygen consumption

Peptide YY (PYY) is a recently discovered polypeptide which has been proposed as physiological inhibitor of pancreatic exocrine secretion. The purpose of this study was to evaluate the effects of exogenous PYY on pancreatic blood flow and oxygen consumption. In anesthetized dogs, the superior pancreatico-duodenal artery blood flow (SPBF), pancreatic microcirculatory blood flow (PBF) and pancreatic oxygen consumption (PVO2) were determined. Control values for SPBF, PVO2 and PBF averaged 43.3 ml/min, 1.8 ml/min, and 57.5 ml/min/100g of tissue, respectively. Following iv injection of PYY at doses of 200 and 400 pmol/kg the values of SPBF decreased by 12 +/- 1% and 22 +/- 2%, respectively. PVO2 was reduced by those doses of PYY by 9 +/- 1 and 17 +/- 3%, respectively. PBF was also reduced by 16 +/- 2 and 34 +/- 2%, respectively after those doses of PYY. Pretreatment with phentolamine reversed the blood flow and PVO2 responses to PYY because SPBF, PVO2 and PBF were significantly increased above the control level. However, after additional pretreatment with propranolol the pancreatic vascular and metabolic responses to PYY were abolished. The above pancreatic responses to PYY were also significantly reduced after acute adrenalectomy. The experimental data indicate that adrenergic pathway is involved in the mechanism of action of PYY on the pancreatic circulation.