Differential effects of lidocaine and tramadol on modified nerve impulse by 4-aminopyridine in rats.
We have used the sucrose gap method to measure the effects of drugs on the electrophysiological properties of rat sciatic nerves. The results showed that 4-aminopyridine produced a slight conduction block, prolonged the duration of action potential, enhanced the hyperpolarizing afterpotential, and elicited a hump that followed the action potential. In the presence of 4-aminopyridine, the impulse-blocking activity of lidocaine and tramadol was enhanced. Both lidocaine and tramadol effectively depressed the delayed depolarization generated by 4-aminopyridine. While tramadol decreased the activity-evoked hyperpolarizing afterpotentials, lidocaine completely removed them. These findings indicate that lidocaine may be more effective in blocking the Na(+) channels than tramadol. Tramadol may be more effective on the delayed rectifier K(+) channels than lidocaine.
Mert
Tufan
T
Department of Biophysics, University of Cukurova, School of Medicine, Balcali, TR-01330 Adana, Turkey. tufanmert@yahoo.com
Gunes
Yasemin
Y
Guven
Mustafa
M
Gunay
Ismail
I
Gocmen
Cemil
C
D015761:4-Aminopyridine / Q000494:pharmacology*; D000200:Action Potentials / Q000187:drug effects*; D000701:Analgesics, Opioid / Q000494:pharmacology*; D000779:Anesthetics, Local / Q000494:pharmacology*; D000818:Animals; D004347:Drug Interactions; D004558:Electric Stimulation; D004594:Electrophysiology; D005260:Female; D008012:Lidocaine / Q000494:pharmacology*; D009431:Neural Conduction / Q000187:drug effects* / Q000502:physiology; D026902:Potassium Channel Blockers / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D012584:Sciatic Nerve / Q000187:drug effects / Q000502:physiology; D014147:Tramadol / Q000494:pharmacology*
D000701:Analgesics, Opioid; D000779:Anesthetics, Local; D026902:Potassium Channel Blockers; D014147:Tramadol; D008012:Lidocaine; D015761:4-Aminopyridine