Inhibitory effects of peptide YY on basal and VIP-stimulated short-circuitcurrent in the rat jejunum: Influence of technical conditions on observed results

The interaction of PYY and VIP was studied in stripped and intact rat jejun um preparations mounted in Ussing chambers. PYY decreased basal Isc in inta ct as well as in stripped jejunum. Stripping was necessary to evidence a st imulation of basal Isc by VIP. When PYY and VIP were administered at the sa me time in the serosal bath, their effects seemed additive; VIP stimulation took over when VIP was present in ten times larger amounts than PYY, while PYY inhibition predominated at isomolar concentrations (10(-7) M) of both peptides. However, when PYY was administered three to six minutes before is omolar amounts of VIP, the VIP stimulation developed without being notably hampered. At this time, however, the amount of radioimmunoaaaayable PYY in the serosal compartment represented still 60% of the added amount. In concl usion, the experimental conditions can significantly change the results: st ripping the longitudinal muscle/myenteric plexus impairs the effect of PYY and VIP in a different fashion, while the timing and order of administratio n of the peptides may change the apparent interaction between VIP stimulati on and PYY inhibition. (C) 1998 Elsevier Science Inc.