不同剂量任氏液灌注对利多卡因阻滞蛙离体坐骨神经时效的影响

Effect of different doses of ringer solution on the duration of nerve block induced by lidocaine in frog sciatic nerve in vitro

目的通过蛙离体坐骨神经灌注模型,观察不同剂量的任氏液灌注对利多卡因阻滞蛙离体坐骨神经时效的影响。方法 20只牛蛙,体重250～300 g。随机将其左右侧离体坐骨神经分入速率1或速率10组。测量并记录让坐骨神经神经干复合动作电位(CAP)振幅达到最大值(CAP_(MAX))的最小刺激强度及CAP_(MAX),在此刺激强度下用1.5%利多卡因浸泡坐骨神经的中间部分,记录CAP_(MAX)完全抑制的时间(t0)。然后速率1组和速率10组分别以1或10 mL/min的速率灌注任氏液,记录CAP开始恢复的时间(t1)和完全恢复的时间(t2)。自任氏液开始灌注起,每隔10 min采集1次CAP振幅,至120 min时为止,并与CAPMAx比较,计算CAP恢复百分率(CAP振幅/CAPMAx)。结果两组间CAP_(MAX)和t0的差异均无统计学意义(P值均>0.05)。速率1组的t1较速率10组有延长趋势,但差异无统计学意义(P=0.078)。速率1组的t2显著长于速率10组(P=0.008),速率10组的t2约较速率1组缩短15%。重复测量的方差分析结果显示,两种任氏液灌注速率对CAP恢复百分率的影响的差异有统计学意义(P=0.011);随着任氏液灌注时间的变化,CAP恢复百分率有显著改变(P<0.01);时间与灌注速率间有交互作用(P=0.028),速率1组和速率10组随着时间的变化CAP恢复百分率的变化不同。结论在蛙离体坐骨神经灌注模型中,增加任氏液灌洗量可缩短利多卡因阻滞蛙离体坐骨神经后的恢复时间,提示组织局部血液量对神经阻滞的时效有显著影响,其程度在15%左右。

Objective To observe the effect of different doses of ringe solution on the duration of nerve block induced by lidocaine in frog sciatic nerve in vitro. Methods Twenty bullfrogs weighing from 250 to 300 g were enrolled in this study. The ex-vivo sciatic nerve of each side of each frog was randomly divided into group of rate 1 and group of rate 10. The maximum amplitude of the compound action potential （CAPMAx） and the minimal stimulus intensity for CAPMAx were measured. The middle of each nerve was bathed with 1.5% lidocaine in this stimulus intensity until CAPMAx was fully suppressed （tO）. Then sciatic nerve of group of rate 1 and group of rate 10 were perfused with ringer solution at the rate of 1 mL/min and 10 mL/min, respectively. The time of initial recovery （tl） and full-recovery （t2） of CAP were recorded. The CAP amplitude was measured every 10 minutes from the beginning of the perfusion and the amplitude ratio of CAP to CAPMAx was calculated until 120 minutes. Results There were no significant defferences in terms of CAPMAx and tO between two groups （P〉 0.05）. Compared with group of rate 10, the tl of group of rate 1 was prolonged, but there was no statistical difference between the two groups （P = 0. 078）. The t2 of group of rate 1 was significantly longer than group of rate 10 （P = 0. 008）. The t2 of group of rate 10 was reduced by 15% as compared with group of rate 1. The repetitive analysis of variance showed the effect of perfusion speed of ringer solution on the recovery of CAP was significantly different between the two groups （P=0.011 ）. The percentage of restored CAP changed significantly with perfusion time （P〈0. 01）. There was interaction between time and perfusion speed （P = 0. 028）. Conclusion The restoring time of sciatic nerve in vitro blocked by lidocaine can be reduced by increasing ringer solution in bullfrog, which suggests that the local blood flow of tissue has appreciable impact on the duration of nerve block, and the duration can be shorten approximately by 15%. （Shanghai Med J, 2012, 35= 688-691）