title: Irreversible selective blockade of kappa-opioid receptors in the guinea-pig ileum.
abstract: The irreversible non-selective opioid antagonist beta-chlornaltrexamine (beta-CNA) was used in combination with selective mu receptor protection by [D-Ala2, MePhe4, Gly(ol)5]enkephalin (DAGO) to produce an effective kappa receptor antagonism in the guinea-pig field-stimulated ileum preparation. Using a standard pre-treatment of 10(-7) M beta-CNA incubated for 15 min, DAG (10(-6)-10(-4) M) protected the response to the mu agonist normorphine while reducing the antagonism of the kappa agonist U50488 to a lesser extent. The concentration of DAGO which produced the most selective protection was 10(-5) M. This method was used to find the kappa selectivity of a series of opioid agonists. Of the compounds tested, butorphanol, dynorphin-(1-17), U50488, tifluadom, bremazocine and Mr 2034 were the most kappa-selective. The correlation with kappa agonist selectivity in vitro and effects in vitro on urine output in the rat is demonstrated.
mesh_terms: D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; D000818:Animals; D004231:Diuresis / Q000187:drug effects; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D004745:Enkephalins / Q000494:pharmacology; D006168:Guinea Pigs; D007082:Ileum / Q000294:innervation; D066298:In Vitro Techniques; D008297:Male; D009022:Morphine Derivatives / Q000494:pharmacology; D009271:Naltrexone / Q000031:analogs & derivatives / Q000494:pharmacology; D011759:Pyrrolidines / Q000494:pharmacology; D011957:Receptors, Opioid / Q000187:drug effects*; D017473:Receptors, Opioid, kappa
chemical_list: D004745:Enkephalins; D009022:Morphine Derivatives; D011759:Pyrrolidines; D011957:Receptors, Opioid; D017473:Receptors, Opioid, kappa; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D009271:Naltrexone; C017120:chlornaltrexamine; D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; C010616:normorphine