Poterack K A, Kampine J P, Schmeling W T
Department of Anesthesiology, Medical College of Wisconsin, Milwaukee 53226.
Anesthesiology. 1991 Oct;75(4):625-33. doi: 10.1097/00000542-199110000-00012.
Normal thermoregulatory processes are significantly impaired by halothane anesthesia. However, the direct effects of halothane on thermosensitive neurons in the preoptic region of the anterior hypothalamus, a major thermoregulatory site, have not been previously investigated. Thirty-eight cats were anesthetized with alpha-chloralose (60 mg/kg) and urethane (600 mg/kg) and placed in stereotactic restraint. Stainless steel thermodes for highly selective local heating and cooling were stereotactically placed into the preoptic region with thermocouples used to monitor regional temperature. Using tungsten microelectrodes, 148 single neurons in the preoptic region were identified and subjected to local heating (to 42 degrees C) and cooling (to 30 degrees C). Eighteen percent (n = 27) in 15 different cats were classified as thermosensitive by accepted criteria (change in firing rate per degree centigrade of greater than 0.8 spikes.s-1.degrees C-1 or less than -0.6 spikes.s-1.degrees C-1). Thermosensitve units were then subjected to graded concentrations of halothane (0.25-1.0% end-tidal), and local heating and cooling were repeated. The spontaneous firing rate (spikes per second) at 37 degrees C of 21 warm-sensitive neurons was significantly (P less than 0.05) reduced, to 65.5 +/- 8.3, 42.6 +/- 10.7, 28.0 +/- 9.5, and 18.1 +/- 6.0% of control at 0.25, 0.50, 0.75, and 1% halothane, respectively. Spontaneous firing rate returned to 99.5 +/- 19.8% of control within 30 min after discontinuation of halothane. Thermosensitivity (change, per degree centigrade, in spikes per second) was also significantly reduced, to 33.3 +/- 5.6, 28.5 +/- 14.6, and 13.9 +/- 6.6% of control at 0.50, 0.75 and 1.0% halothane (all P less than 0.05 compared to control).(ABSTRACT TRUNCATED AT 250 WORDS)
氟烷麻醉会显著损害正常的体温调节过程。然而，氟烷对下丘脑前部视前区（一个主要的体温调节部位）的热敏神经元的直接作用此前尚未被研究过。38只猫用α-氯醛糖（60毫克/千克）和乌拉坦（600毫克/千克）麻醉，并置于立体定位约束装置中。用于高度选择性局部加热和冷却的不锈钢热电极通过立体定位放置在视前区，并用热电偶监测局部温度。使用钨微电极，在视前区识别出148个单个神经元，并对其进行局部加热（至42摄氏度）和冷却（至30摄氏度）。按照公认标准，15只不同猫中的18%（n = 27）被归类为热敏神经元（每摄氏度放电频率变化大于0.8个脉冲/秒·摄氏度或小于-0.6个脉冲/秒·摄氏度）。然后让热敏神经元接受不同浓度的氟烷（呼气末浓度为0.25 - 1.0%），并重复局部加热和冷却操作。21个温敏神经元在37摄氏度时的自发放电频率（每秒脉冲数）在氟烷浓度为0.25%、0.50%、0.75%和1%时分别显著（P < 0.05）降低至对照值的65.5 ± 8.3%、42.6 ± 10.7%、28.0 ± 9.5%和18.1 ± 6.0%。停止使用氟烷后30分钟内，自发放电频率恢复至对照值的99.5 ± 19.8%。热敏性（每秒脉冲数每摄氏度的变化）在氟烷浓度为0.50%、0.75%和1.0%时也显著降低至对照值的33.3 ± 5.6%、28.5 ± 14.6%和13.9 ± 6.6%（与对照相比，所有P < 0.05）。（摘要截选至250字）
