Potentiation of presynaptic inhibition of nociceptive pathways as a mechanism for analgesia.
In decerebrated spinal cats, stimulation of cutaneous A delta and C afferents and intraarterial injections of bradykinin into a hind limb produced a reduction in the threshold for antidromic activation in the substantia gelatinosa of single C fibres. Meperidine increased the unconditioned threshold but potentiated the decrease in the threshold produced by A delta fibre stimulation and by bradykinin injection. These results support the suggestion that myelinated cutaneous afferents can depolarize C afferent terminals. The observations also indicate that the depolarization of C afferent terminals produced during pain and by stimulation of other cutaneous afferents is potentiated by meperidine.
D000700:Analgesics / Q000494:pharmacology*; D000818:Animals; D001920:Bradykinin / Q000494:pharmacology; D002415:Cats; D004558:Electric Stimulation; D008614:Meperidine / Q000494:pharmacology; D009411:Nerve Endings / Q000187:drug effects; D009433:Neural Inhibition / Q000187:drug effects; D009434:Neural Pathways / Q000187:drug effects*; D010146:Pain / Q000503:physiopathology*; D013569:Synapses / Q000187:drug effects*; D013997:Time Factors
D000700:Analgesics; D008614:Meperidine; D001920:Bradykinin