Abstract
Morphine, enkephalins, nalorphine, naloxone and pentazocine are shown to have a peripheral analgesic effect. In our modification of the Randall-Selitto test these substances were 50--100 times more potent than a standard local anaesthetic, lidocaine. At this peripheral site, naloxone did not antagonize the effect of morphine. Morphine had a marked analgesic effect on the hyperalgesia induced by PGE2 and PGI2, BaCl2, Ca2+ ionophore A23187, isoprenaline but not on that induced by dibutyryl cyclic AMP. It was suggested that the peripheral analgesic effect of morphine is due to an inhibition of adenylate-cyclase activity.
MeSH terms
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Analgesics*
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Animals
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Barium / pharmacology
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Bucladesine / pharmacology
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Endorphins / pharmacology*
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Enkephalins / pharmacology*
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Hyperalgesia / chemically induced*
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Hyperesthesia / chemically induced*
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Ionophores / pharmacology
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Isoproterenol / pharmacology
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Lidocaine / pharmacology
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Morphine / pharmacology*
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Nalorphine / pharmacology
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Naloxone / pharmacology
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Narcotic Antagonists / pharmacology*
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Nociceptors / drug effects*
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Pentazocine / pharmacology
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Prostaglandins E / pharmacology*
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Rats
Substances
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Analgesics
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Endorphins
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Enkephalins
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Ionophores
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Narcotic Antagonists
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Prostaglandins E
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Barium
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Naloxone
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Bucladesine
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Morphine
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Lidocaine
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Isoproterenol
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Pentazocine
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Nalorphine