title: Reflex peristalsis in the guinea pig isolated ileum is endogenously controlled by kappa opioid receptors.
abstract: (1) Reflex peristalsis in the circular muscle of the guinea pig ileum was elicited in vitro by sustained luminal distension of the intestinal wall according to 2 cm H2O and evaluated in terms of the number of peristaltic waves within 15 min intervals. (2) The poorly mu-selective opioid antagonist naloxone at concentrations of 10(-7) and 10(-6) mol/l increased the frequency of peristaltic contractions within the first 15 min interval, and thereafter in a declining fashion, by 68 and 88%, respectively. The highly kappa-selective opioid antagonist nor-binaltorphimine behaved similarly. It was, by one order of magnitude, more potent but a little less effective than naloxone, i.e., the maximum effect was 57% increase in peristaltic frequency at 10(-8) mol/l. Concentrations of 10(-7) and 10(-6) mol/l had the same effect as 10(-8) mol/l, and 10(-9) mol/l were ineffective. The highly mu-selective antagonist CTOP-NH2 and the highly delta-selective antagonist ICI 174,864 were ineffective up to 10(-6) mol/l. (3) It is concluded that predominantly kappa opioid receptors are used by endogenous opioids under the present conditions to inhibit reflex peristalsis.
authors.affiliation: Byk Gulden Pharmaceuticals, Department of Pharmacology, Konstanz, Federal Republic of Germany.
authors.forename: W
authors.initials: W
authors.lastname: Kromer
mesh_terms: D000818:Animals; D004305:Dose-Response Relationship, Drug; D004743:Enkephalin, Leucine / Q000031:analogs & derivatives / Q000494:pharmacology; D005769:Gastrointestinal Motility / Q000502:physiology*; D006168:Guinea Pigs; D007082:Ileum / Q000502:physiology* / Q000648:ultrastructure; D008297:Male; D009270:Naloxone / Q000494:pharmacology; D009271:Naltrexone / Q000031:analogs & derivatives / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D010528:Peristalsis / Q000187:drug effects / Q000502:physiology*; D011957:Receptors, Opioid / Q000502:physiology*; D017473:Receptors, Opioid, kappa; D012018:Reflex / Q000187:drug effects / Q000502:physiology*; D013004:Somatostatin / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D009292:Narcotic Antagonists; D011957:Receptors, Opioid; D017473:Receptors, Opioid, kappa; C049352:phenylalanyl-cyclo(cysteinyltyrosyl-tryptophyl-ornithyl-threonyl-penicillamine)threoninamide; D009270:Naloxone; C051844:norbinaltorphimine; D013004:Somatostatin; D004743:Enkephalin, Leucine; D009271:Naltrexone; C040643:N,N-diallyl-tyrosyl-alpha-aminoisobutyric acid-phenylalanyl-leucine