Section 41
Chapter 40,659

Mechanism of inhibitory action of peptide YY on cholecystokinin-induced contractions of isolated dog ileum

Baba, H.; Fujimura, M.; Toda, N.

Regulatory Peptides 27(2): 227-235


ISSN/ISBN: 0167-0115
PMID: 2326499
DOI: 10.1016/0167-0115(90)90041-t
Accession: 040658856

In isolated canine ileal longitudinal muscle preparations, cholecystokinin-octapeptide (CCK-8) produced a concentration-dependent contraction, which was suppressed by peptide YY (PYY) and was abolished by tetrodotoxin and atropine. PYY was approximately 2200-times as potent as CR1505, a CCK-receptor antagonist. PYY opposed the action of CCK-8 to a greater extent than that of nicotine and transmural electrical stimulation. Acetylcholine-induced contractions were not influenced by PYY. It seems likely that the CCK-8-induced ileal muscle contraction is associated with an activation of CCK receptors in cholinergic nerves, which generates nerve action potentials and releases acetylcholine, whereas CCK-8 acts on CCK receptors in gallbladder smooth muscle, producing contractions. It may be concluded that PYY inhibits the action of CCK-8 on ileal muscle strips, by inhibiting the release of acetylcholine from cholinergic nerve terminals. On the other hand, in the gallbladder, PYY does not appear to block cholinergic nerve function.

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