Abstract
The novel heptadecapeptide opioid, nociceptin, produced a concentration-dependent (EC50 28 nM) suppression of the inotropic response of the guinea-pig isolated renal pelvis to electrical stimulation, a response mediated by release of tachykinins from sensory nerves. Nociceptin did not affect the response to neurokinin A, indicating a prejunctional site of action on tachykininergic nerves. The effect of nociceptin was unchanged in the presence of the mu, delta and kappa opioid receptor antagonists, naloxone, naltrindole and nor-binaltorphimine.
MeSH terms
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Animals
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Electric Stimulation
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Guinea Pigs
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In Vitro Techniques
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Kidney Pelvis / drug effects
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Male
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Muscle Contraction / drug effects
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Narcotic Antagonists / pharmacology
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Nerve Endings / drug effects
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Nerve Endings / metabolism*
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Neurokinin A / pharmacology
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Neurons, Afferent / metabolism*
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Nociceptin
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Opioid Peptides / pharmacology*
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Peripheral Nerves / cytology
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Peripheral Nerves / drug effects
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Peripheral Nerves / metabolism*
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Receptors, Opioid / agonists*
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Tachykinins / metabolism*
Substances
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Narcotic Antagonists
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Opioid Peptides
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Receptors, Opioid
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Tachykinins
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Neurokinin A