Anesthetic action of volatile anesthetics by using Paramecium as a model

Although empirically well understood in their clinical administration, volatile anesthetics are not yet well comprehended in their mechanism studies. A major conundrum emerging from these studies is that there is no validated model to assess the presumed candidate sites of the anesthetics. We undertook this study to test the hypothesis that the single-celled Paramecium could be anesthetized and served as a model organism in the study of anesthetics. We assessed the motion of Paramecium cells with Expert Vision system and the chemoresponse of Paramecium cells with T-maze assays in the presence of four different volatile anesthetics, including isoflurane, sevoflurane, enflurane and ether. Each of those volatiles was dissolved in buffers to give drug concentrations equal to 0.8, 1.0, and 1.2 EC50, respectively, in clinical practice. We could see that after application of volatile anesthetics, the swimming of the Paramecium cells was accelerated and then suppressed, or even stopped eventually, and the index of the chemoresponse of the Paramecium cells (denoted as Iche) was decreased. All of the above impacts were found in a concentration-dependent fashion. The biphasic effects of the clinical concentrations of volatile anesthetics on Paramecium simulated the situation of high species in anesthesia, and the inhibition of the chemoresponse also indicated anesthetized. In conclusion, the findings in our studies suggested that the single-celled Paramecium could be anesthetized with clinical concentrations of volatile anesthetics and therefore be utilized as a model organism to study the mechanisms of volatile anesthetics.     

右美托咪定喷鼻对全麻患儿神经认知恢复延迟的影响

目的观察术前经鼻腔喷雾右美托咪定对全麻患儿神经认知功能恢复延迟发生率和其血清S100β含量和IL-6浓度的影响。方法选择择期在全麻下行扁桃体腺样体切除术的患儿70例,男42例,女28例,年龄6~8岁,ASAⅠ或Ⅱ级。采用随机数字表法分为右美托咪定组(D组)和对照组(C组),每组35例。在麻醉诱导前30 min使用鼻腔喷雾装置,D组给予右美托咪定2.0μg/kg,C组给予0.02 ml/kg的生理盐水。评估患儿拔管后30 min时镇静评分(Ramsay评分)和改良加拿大东安大略儿童医院疼痛评分(m-CHEOPS评分),当m-CHEOPS评分>5分时,给予芬太尼0.5μg/kg补救镇痛,记录术后芬太尼使用情况。分别于术前1 d、术后1、3和30 d记录两组患儿简易智力状态检查量表(MMSE)评分,并于术前1 d、术后1和3 d采集外周静脉血,检测血清S100β含量和IL-6浓度。记录术后恶心呕吐、喉痉挛、低血压、呼吸抑制和心动过缓等不良反应发生情况。结果与C组比较,D组术后Ramsay镇静评分明显升高(P<0.05),m-CHEOPS评分明显降低(P<0.05),芬太尼使用明显减少(P<0.05)。与术前1 d比较,术后1和3 d两组MMSE评分明显降低(P<0.05)。术后1和3 d,D组MMSE评分明显高于C组(P<0.05),D组神经认知功能恢复延迟发生率明显低于C组(P<0.05)。与术前1 d比较,术后1和3 d两组血清S100β含量和IL-6浓度明显升高(P<0.05)。术后1和3 d,D组血清S100β含量和IL-6浓度明显低于C组(P<0.05)。两组恶心呕吐、喉痉挛、低血压、呼吸抑制和心动过缓等不良反应发生情况差异无统计学意义。结论麻醉诱导前30 min经鼻喷雾右美托咪定2.0μg/kg,可有效抑制血清中S100β含量和IL-6浓度的升高,减少全麻患儿神经认知恢复延迟的发生。