Comparative effects of lidocaine and tramadol on injured peripheral nerves.
The aim of the present study was to investigate the action of lidocaine and tramadol on the abnormal impulse characteristics of injured peripheral nerves. The ultrastructure of nerves was studied with electron microscopy and the action of lidocaine and tramadol on intact and injured rat sciatic nerves was examined by using the sucrose gap recording technique. Tramadol and lidocaine caused concentration- and frequency-dependent decreases in the amplitude of the compound action potential. Injured nerves were more sensitive to lidocaine than to tramadol. Lidocaine suppressed the delayed depolarization and decreased the hyperpolarizing afterpotentials to a greater extent than did tramadol. A low concentration of lidocaine may restore the abnormal impulse characteristics of injured nerves without changing the normal impulse pattern. The efficacy of lidocaine and inefficacy of tramadol on abnormal impulse characteristics may contribute, at least in part, to our understanding of the mechanisms of action of these drugs in neuropathic pain therapy.
Mert
Tufan
T
Department of Biophysics, School of Medicine, University of Cukurova, 01330 Balcali, Adana, Turkey. tufanmert@yahoo.com
Gunes
Yasemin
Y
Ozcengiz
Dilek
D
Gunay
Ismail
I
Polat
Sait
S
D015761:4-Aminopyridine / Q000494:pharmacology; D000200:Action Potentials / Q000187:drug effects; D000701:Analgesics, Opioid / Q000494:pharmacology* / Q000627:therapeutic use; D000779:Anesthetics, Local / Q000494:pharmacology* / Q000627:therapeutic use; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D004594:Electrophysiology; D005260:Female; D008012:Lidocaine / Q000494:pharmacology* / Q000627:therapeutic use; D009431:Neural Conduction / Q000187:drug effects; D009437:Neuralgia / Q000188:drug therapy / Q000378:metabolism; D026902:Potassium Channel Blockers / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012584:Sciatic Nerve / Q000187:drug effects* / Q000378:metabolism / Q000503:physiopathology / Q000601:surgery; D015222:Sodium Channels / Q000187:drug effects / Q000378:metabolism; D013997:Time Factors; D014147:Tramadol / Q000494:pharmacology* / Q000627:therapeutic use
D000701:Analgesics, Opioid; D000779:Anesthetics, Local; D026902:Potassium Channel Blockers; D015222:Sodium Channels; D014147:Tramadol; D008012:Lidocaine; D015761:4-Aminopyridine