Neuropeptide Y is a proabsorptive agent in the small intestine

In the mammalian intestine neuropeptide Y (NPY) is contained in sympathetic nerves and in enteric neurons originating from the myenteric and submucosal plexuses. This study investigated the role of NPY on small intestinal ionic transport using an isolated intestinal preparation. Rabbit ileal segments (n = 12) were harvested and arterially perfused with a nonrecirculating oxygenated sanguinous solution. The intestinal lumen was perfused with an isotonic solution containing [14C]PEG. Net fluxes of H2O, Na+, and Cl- were calculated for three 20-min periods: basal, drug infusion, and recovery. Two groups were studied: (1) NPY 50 pM/min (n = 6) and (2) NPY 500 pM/min (n = 6). NPY at 50 pM/min caused modest absorption and at 500 pM/min yielded a significant proabsorptive effect (P less than 0.05) for H2O, Na+, and Cl- during the drug infusion period. There were no significant changes in vascular perfusion pressure in either group. These data demonstrate a significant proabsorptive effect of NPY on water and electrolyte transport in the isolated perfused ileum. This proabsorptive effect occurs at a constant arterial blood flow and without alteration in perfusion pressure, supporting a direct effect of NPY on intestinal ionic transport.