title: Dexmedetomidine augments the effect of lidocaine: power spectrum and nerve conduction velocity distribution study.
abstract: BACKGROUND
  In this study, the individual and combined inhibitory effects of dexmedetomidine and lidocaine on the conduction group of isolated nerve were investigated by determining conduction velocity distribution (CVD) and power spectrum.
  
  
  METHODS
  Electrophysiological compound action potential (CAP) recordings were conducted on isolated rat sciatic nerve before (Con) and 20 minutes after exposure to 1 mM lidocaine (Lido), 21pM dexmedetomidine (Dex) and their combination (Lido + Dex). Then for CVD, mathematical model and for power spectrum Fast Fourier analysis were conducted.
  
  
  RESULTS
  Dexmedetomidine alone made no significant difference in shape and duration of CAPs as compared to Con, on the other hand lidocaine depresses amplitude and prolongs the duration of CAPs, but not more than combination of dexmedetomidine and lidocaine can do. Lidocaine caused a shift in the CVD histogram to relatively slower conducting group significantly while dexmedetomidine did not cause any significant change as compared to Control. Lidocaine, when combined with dexmedetomidine revealed a remarkable effect on the whole CVD histogram by causing almost complete blockage of fast conducting nerve fibers. The relative number of fibers in CVD is conserved for separate applications of anesthetics, but not for their combination. As in CVD, power spectrum shifted from higher to lower frequency region by lidocaine and significantly for lidocaine combined with dexmedetomidine application. Shifts for dexmedetomidine applied group were seen beggarly.
  
  
  CONCLUSIONS
  We have concluded that dexmedetomidine alone did not influence nerve conduction, but when it is used with lidocaine it augments neural conduction blockage effect, especially on fast conducting nerve fibers.
authors.affiliation: N.E. University, Meram School of Medicine, Biophysics Department, Konya, Turkey.
authors.forename: Nizamettin
authors.initials: N
authors.lastname: Dalkilic
authors.affiliation: N.E. University, Meram School of Medicine, Biophysics Department, Konya, Turkey.
authors.forename: Seckin
authors.initials: S
authors.lastname: Tuncer
authors.affiliation: N.E. University, Meram School of Medicine, Biophysics Department, Konya, Turkey.
authors.forename: Ilksen
authors.initials: I
authors.lastname: Burat
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000779:Anesthetics, Local / Q000494:pharmacology; D000818:Animals; D020927:Dexmedetomidine / Q000494:pharmacology*; D004357:Drug Synergism; D005583:Fourier Analysis; D008012:Lidocaine / Q000494:pharmacology*; D009431:Neural Conduction / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D012584:Sciatic Nerve / Q000187:drug effects / Q000502:physiology
chemical_list: D000779:Anesthetics, Local; D020927:Dexmedetomidine; D008012:Lidocaine
keywords: Conduction velocity distribution; Dexmedetomidine; Lidocaine; Neural conduction blockage; Power spectrum