背景與目的： 傳統上閃尾測試是在老鼠清醒下進行。為避免老鼠掙扎及壓力，適當的鎮靜(sedation) 有其必要。然而以吸入性氣體提供鎮靜是否會造成閃尾測試的影響，一直沒有報導。反覆在定點燒灼也容易造成尾部的灼傷，因此栘動照射點實屬必要，然而不同部位(tail, body, or root) 的照射敏感度是否相同，仍無報導！本研究之目的在測試不同濃度的Halothane 麻醉下的閃尾反應。方法： 取15 隻SD 老鼠稱其體重並且量尾巴長度，將老鼠尾巴平均區分成三部份：末端1/3 (tail),中間1/3 (body),靠近身體的1/3 (root)。老鼠放置於精心設計的chamber 中，只有尾部暴露在外面，在不同濃度的halothane(0.5%, 0.75%, 1.0%, 1.25%, 1.5%)麻醉下，測量其不同部位的閃尾時間(tailflicklatency,TFL) 並記錄之。結果：1.在halothane (1MAC= 0.75%) 濃度為0.5%和0.75%的麻醉狀態下，閃尾時間並無明顯差異，而且與測試部位無關。但是在濃度為0.5%和1.0%以及0.75%和1.0%之間有明顯差異。濃度為1.0%和1.25%以及1.0%和1.5%之間也有明顯差異。2.在同樣濃度的halothane麻醉下，發現尾部(tail)和體部(body) 的閃尾時間有所差異。結論: 閃尾時間隨著Halothane濃度的增加而延長，而且與尾巴部位有關。

Background and Purpose: Tail-flick latency in the rat is commonly used to measure thethermo-nociceptive response and the antinociceptive effect of various analgesic regimens. Inconscious animal models, the rats are usually restrained, and the profound stress can lead tointerferencewith the nociceptive measurement as a result of stress-induced analgesia. Although ithas been reported that mild to moderate intravenous (I.V.) anesthesia does not affect latency, fewreports have described the effect of inhalation anesthesia on the tail flick latency in rats. Thepurpose of the present study was to determine whether halothane-mediated suppression of thetail-flick response is concentration dependent. Methods: Tail-flick latencies weremeasured in 15Sprague-Dawley rats weighing 250~300 g, anesthetized by either 0.5%, 0.75%, 1.0%, 1.25%, or 1.5%halothane. High-intensity light focused on points in either the proximal,middle, or distal 1/3 of thetail heated these sites to 37 (C and served as the stimulus. The cutoff latency was 10 s. Results:No difference in latency was found between rats under 0.5% and 0.75% halothane anesthesia.Dose-dependent prolongation of latency was noted in rats anesthetized with between 0.5% and1.0% halothane. However, we found that the tail-flick reflex to noxious heat was completelyeliminated by ? 1.25% halothane. Conclusion: Between 0.5% and 1.0%, but not greater than1.25%, halothane dose-dependently suppressed the tail-flick latency in the rat. We suggest thatcareful titration of halothane concentrations can serve as an ideal anesthetic regimen to measuretail-flick latency.