Characterization of opioid receptors modulating the function of capsaicin-sensitive neurons in guinea-pig atria.
Transmural nerve stimulation of isolated atria, obtained from reserpine-pretreated guinea-pigs, in the presence of atropine and the beta 1-adrenoceptor-blocking drug CGP 20712A, induced a positive inotropic effect. [D-Ala2,N-Me-Phe4,Gly5-ol]enkephalin (DAGO), [D-Ala2,D-Leu5]enkephalin (DADLE), morphine and dynorphin dose dependently reduced the cardiac response to transmural nerve stimulation. The delta receptor selective agonist [D-Pen2,D-Pen5]enkephalin (DPDPE), and the kappa receptor agonist, U50488, were unable modify the response. The inhibitory effect of all the active opioid agonists was antagonized by naloxone but not by the selective delta and kappa opioid receptor antagonists, ICI 174.864 and MR 2266. These results suggest the presence on sensory nerve terminals of inhibitory opioid receptors belonging to the mu, but not to the delta and kappa subtypes.
Mantelli
L
L
Department of Pharmacology, University of Florence, Italy.
Amerini
S
S
Rubino
A
A
Ledda
F
F
D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D001575:Benzomorphans / Q000494:pharmacology; D002211:Capsaicin / Q000494:pharmacology*; D004399:Dynorphins / Q000494:pharmacology; D004558:Electric Stimulation; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D020881:Enkephalin, D-Penicillamine (2,5)-; D004743:Enkephalin, Leucine / Q000031:analogs & derivatives / Q000494:pharmacology; D016308:Enkephalin, Leucine-2-Alanine; D004745:Enkephalins / Q000494:pharmacology; D006168:Guinea Pigs; D006321:Heart / Q000187:drug effects* / Q000294:innervation; D007093:Imidazoles / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D009020:Morphine / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects*; D011759:Pyrrolidines / Q000494:pharmacology; D011957:Receptors, Opioid / Q000187:drug effects*; D012110:Reserpine / Q000494:pharmacology
D000319:Adrenergic beta-Antagonists; D001575:Benzomorphans; D004745:Enkephalins; D007093:Imidazoles; D011759:Pyrrolidines; D011957:Receptors, Opioid; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; C027247:MR 2266; D004743:Enkephalin, Leucine; D016308:Enkephalin, Leucine-2-Alanine; D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; D004399:Dynorphins; D009020:Morphine; D020881:Enkephalin, D-Penicillamine (2,5)-; C040643:N,N-diallyl-tyrosyl-alpha-aminoisobutyric acid-phenylalanyl-leucine; D012110:Reserpine; C049763:CGP 20712A; D002211:Capsaicin