Presynaptic excitability changes induced by morphine in single cutaneous afferent C- and A-fibers.
Intraspinal microstimulation was used to test the excitability of single cutaneous (sural) A- and C-fibers at their central terminals in the cat. Systemic morphine (1.0-2.6 mg/kg) increased the antidromic threshold to 110% (mean value) of control in C-fibers. In some of the C-fibers this effect was reversed by naloxone. A-fibers were not consistently affected by mophine.
D000818:Animals; D002415:Cats; D009020:Morphine / Q000494:pharmacology*; D009270:Naloxone / Q000494:pharmacology; D009412:Nerve Fibers / Q000187:drug effects*; D009413:Nerve Fibers, Myelinated / Q000187:drug effects; D009475:Neurons, Afferent / Q000187:drug effects; D012867:Skin / Q000294:innervation*; D013126:Spinal Nerve Roots / Q000187:drug effects
D009270:Naloxone; D009020:Morphine