Opiates inhibit the discharges of fine afferent units from inflamed knee joint of the cat.
The spontaneous discharges in 15 out of 19 small-diameter afferent units from inflamed knee joints of anaesthetized cats were significantly inhibited by one or several opiates (morphine in the dose range 1.0-5.0 mg/kg; gly-ol 0.5-5.0 mg/kg; U50488 1.0-10.0 mg/kg; ethylketocyclazacine 0.5-4.0 mg/kg administered by close arterial injection into the joint). In the majority of cases a subsequent injection of naloxone (1 mg/kg i.a.) significantly reversed this effect. These data provide an electrophysiological demonstration that opiates may act on opiate receptors located at peripheral sites of primary afferent fibres and hence exert a peripheral 'analgesic' effect.
D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; D000701:Analgesics, Opioid / Q000494:pharmacology*; D000818:Animals; D001168:Arthritis / Q000188:drug therapy; D002415:Cats; D003496:Cyclazocine / Q000031:analogs & derivatives / Q000494:pharmacology; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D004745:Enkephalins / Q000494:pharmacology; D016314:Ethylketocyclazocine; D009020:Morphine / Q000494:pharmacology; D009270:Naloxone / Q000494:pharmacology; D009619:Nociceptors / Q000187:drug effects*; D010146:Pain / Q000188:drug therapy; D010525:Peripheral Nerves / Q000187:drug effects*; D011759:Pyrrolidines / Q000494:pharmacology
D000701:Analgesics, Opioid; D004745:Enkephalins; D011759:Pyrrolidines; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D009270:Naloxone; D016314:Ethylketocyclazocine; D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; D009020:Morphine; D003496:Cyclazocine