Peptide YY-induced alteration of colonic electrolyte transport in the rat

The effect of peptide YY (PYY) on active electrolyte transport in rat colon was studied under short-circuited conditions. PYY (10(-6) M) decreased the basal short-circuit current (Isc) in both the distal and proximal segments of the colon. The decrease in Isc induced by PYY in the distal colon was about 3 times larger than that in the proximal colon. The response to PYY was inhibited by diphenylamine 2-carboxylate, a specific blocker of the Cl-channel, but not by amiloride, a Na-channel blocker. Unidirectional flux measurements in the distal colon revealed that PYY increased the net Na and Cl absorption and decreased the serosal-to-mucosal Cl flux. PYY inhibited the neurally mediated secretory response to electrical field stimulation in a concentration-dependent manner. PYY was also shown to reduce the direct action of the cholinergic agonist bethanechol on the epithelium. These results suggest that PYY inhibits electrogenic Cl secretion and stimulates electroneutral NaCl absorption via both presynaptic and postsynaptic sites in the distal colon.