Mechanism of inhibitory action of peptide YY on cholecystokinin-induced contractions of isolated dog ileum.
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.
Baba
H
H
Department of Pharmacology, Shiga University of Medical Sciences, Ohtsu, Japan.
Fujimura
M
M
Toda
N
N
D000818:Animals; D002766:Cholecystokinin / Q000494:pharmacology; D004285:Dogs; D005260:Female; D005704:Gallbladder / Q000187:drug effects / Q000502:physiology*; D005973:Glutamine / Q000031:analogs & derivatives*; D007082:Ileum / Q000187:drug effects / Q000502:physiology*; D007537:Isometric Contraction / Q000187:drug effects*; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D019894:Peptide YY; D010455:Peptides / Q000494:pharmacology*; D011377:Proglumide / Q000031:analogs & derivatives* / Q000494:pharmacology; D012844:Sincalide / Q000494:pharmacology*
D010455:Peptides; D005973:Glutamine; D019894:Peptide YY; C053737:loxiglumide; D002766:Cholecystokinin; D011377:Proglumide; D012844:Sincalide