Dalkilic Nizamettin, Tuncer Seckin, Bariskaner Hulagu, Kiziltan Erhan
Selcuk Univercity Meram Medical Faculty, Department of Biophysics, Turkey.
Yakugaku Zasshi. 2009 Apr;129(4):485-93. doi: 10.1248/yakushi.129.485.
The aim of this study was to document the effect of tramadol as an opioid on individual fibers of rat sciatic nerve. To accomplish this objective, compound action potentials (CAPs) were recorded from isolated nerves treated with tramadol from five different concentration levels. Then recorded CAPs and the control group were analyzed by numerical methods namely Conduction Velocity Distribution (CVD) and Fast Fourier Transform (FFT). The results show that the area under CAP and the time derivative of CAP curves decreases, and the excitability of the nerve trunk falls as well (rheobase and chronaxie increases) with increasing tramadol concentration. CVD deduced by model study was divided into subgroups as SLOW (8-26 m/s), MODERATE (26-44 m/s), MEDIUM (44-60 m/s) and FAST (60-78 m/s). The decrement in percentage relative contribution of these conduction velocity groups starts with a concentration of 0.25 mM tramadol, especially in the subgroup named FAST. The power spectrum shifts from higher frequency region to lower frequency region as the tramadol concentration increases. These findings show that fast conducting fibers are more susceptible to tramadol than medium and moderate groups and tramadol possibly acts on channel activity rather than passive properties (such as space and time constant) of nerve fibers.
本研究的目的是记录曲马多作为一种阿片类药物对大鼠坐骨神经单个纤维的作用。为实现这一目标，从用五种不同浓度水平的曲马多处理过的离体神经记录复合动作电位（CAPs）。然后通过传导速度分布（CVD）和快速傅里叶变换（FFT）等数值方法对记录的CAPs和对照组进行分析。结果表明，随着曲马多浓度增加，CAPs曲线下面积和CAPs曲线的时间导数减小，神经干的兴奋性也下降（基强度和时值增加）。通过模型研究推导的CVD被分为SLOW（8 - 26 m/s）、MODERATE（26 - 44 m/s）、MEDIUM（44 - 60 m/s）和FAST（60 - 78 m/s）亚组。这些传导速度组的相对贡献百分比的下降从曲马多浓度为0.25 mM开始，尤其是在名为FAST的亚组中。随着曲马多浓度增加，功率谱从高频区域向低频区域移动。这些发现表明，快速传导纤维比中等和适度传导组对曲马多更敏感，并且曲马多可能作用于神经纤维的通道活性而非被动特性（如空间和时间常数）。
