Peptide YY is a physiological regulator of water and electrolyte absorption in the canine small bowel in vivo

Background: Peptide YY (PYY), a hormone released following a meal, is one potential mediator of intestinal absorption. Although PYY inhibits 5′-cyclic adenosine monophosphate (cAMP)-stimulated small intestinal secretion in vitro, its effects on fluid and electrolyte transport in vivo are unknown. Methods: This study examines the effects of physiological doses of PYY in dogs (n = 6) with jejunal and ileal exteriorized, neurovascularly intact intestinal loops (Thiry-Vella fistulas). Results: Plasma PYY levels increased after a meal from 155 ± 15 to 324 ± 26 pmol/L at 30 minutes and remained elevated for 2 hours. PYY infused intravenously in unfed animals at 25, 50, 100, and 200 pmol · kg^-1 · h^-1, produced a dose-dependent increase in plasma PYY levels. At 100 pmol · kg^-1 · h^-1, PYY plasma concentrations were similar to those of fed animals (317 ± 39 pmol/L). PYY infusion resulted in a dose-dependent increase in water and electrolyte absorption at all doses in both the jejunum and ileum. Although the relative increase in absorption was similar, the magnitude was greater in the ileum. Conclusions: Physiological concentrations of PYY produced an increase in small bowel absorption of water and electrolytes in vivo. The postprandial release of PYY may mediate the increase in absorption following a meal. Such a proabsorptive agent may have considerable potential for clinical use in malabsorptive states.