Graduate Institute of Acupuncture Science, College of Chinese Medicine, China Medical University, Taichung, Taiwan.
Eur J Pain. 2011 Jul;15(6):600-7. doi: 10.1016/j.ejpain.2010.11.002. Epub 2010 Dec 4.
The use of anesthetics to stabilize animals for the purpose of electroacupuncture (EA) analgesic studies can be problematic because of the interference of differential physiological responses to EA and pain. In this study, EA-induced physiological profiles were surveyed under a sub-minimal alveolar concentration (sub-MAC) of two different anesthetics in a previously proposed minimal stress model. First, to select an adequate concentration, compliance with EA and tail-flick stimulation was evaluated under various concentrations of halothane and isoflurane. Second, using the chosen concentrations, low- (4-Hz) and high-frequency (100-Hz) EA were conducted on the right hind limb. The EA effects of the two gases were compared by tail-flick latency (TFL), hemodynamic variables, and individual variations in analgesic sensitivity. The optimal concentrations for halothane and isoflurane were 0.5% and 0.75%, respectively. TFLs were stable under these anesthetic levels, but rats under 0.75% isoflurane had better compliance than those under 0.5% halothane. EA inhibited TFLs with distinct analgesic patterns when comparing high- and low-frequency EA, but TFL suppression did not differ between the two gases. Heart rate and blood pressure showed temporal and differential responses to low- vs. high-frequency EA, but were comparable between groups under the two anesthetics. The ratios of EA non-responders in the isoflurane and halothane groups were 32.4% and 26.7%, respectively, without statistical difference. We concluded that sub-MAC halothane and isoflurane provide optimal conditions for the study of EA-induced analgesia in rats. In this model, 0.75% isoflurane appears to be a better choice than 0.5% halothane in terms of EA compliance.
在进行电针（EA）镇痛研究时，使用麻醉剂稳定动物可能会出现问题，因为麻醉剂会干扰对 EA 和疼痛的不同生理反应。在这项研究中，在之前提出的最小应激模型中，在两种不同麻醉剂的亚最小肺泡浓度（sub-MAC）下，调查了 EA 诱导的生理谱。首先，为了选择适当的浓度，评估了在不同浓度的氟烷和异氟烷下对 EA 和尾巴闪烁刺激的顺应性。其次，使用选定的浓度，对右后肢进行低频（4-Hz）和高频（100-Hz）EA。通过尾巴闪烁潜伏期（TFL）、血液动力学变量和个体镇痛敏感性的个体差异比较两种气体的 EA 效应。氟烷和异氟烷的最佳浓度分别为 0.5%和 0.75%。在这些麻醉水平下，TFL 稳定，但在 0.75%异氟烷下的大鼠比在 0.5%氟烷下的大鼠具有更好的顺应性。当比较高低频 EA 时，EA 抑制 TFL 具有明显的镇痛模式，但两种气体之间 TFL 抑制没有差异。心率和血压对低频与高频 EA 表现出时间和差异反应，但在两种麻醉剂下，各组之间相当。异氟烷和氟烷组中 EA 无反应者的比例分别为 32.4%和 26.7%，无统计学差异。我们得出结论，亚 MAC 氟烷和异氟烷为大鼠 EA 诱导镇痛研究提供了最佳条件。在这种模型中，0.75%异氟烷在 EA 顺应性方面似乎比 0.5%氟烷更好。
