Mackensen G B, Nellgård B, Miura Y, Chu C T, Dexter F, Pearlstein R D, Warner D S
Department of Anesthesiology, Klinikum rechts der Isar, Technische Universität München, Munich, Germany.
Anesthesiology. 1999 Mar;90(3):873-81. doi: 10.1097/00000542-199903000-00031.
Isoflurane-anesthetized rats have better outcome from global cerebral ischemia than rats anesthetized with fentanyl and nitrous oxide. The authors wanted to determine whether circulating catecholamine concentrations depend on the anesthetic agent and whether sympathetic ganglionic blockade affects anesthetic-mediated differences in outcome from near-complete forebrain ischemia.
For two different experiments, normothermic Sprague-Dawley rats that had fasted were assigned to one of four groups and subjected to 10 min of 30 mm Hg mean arterial pressure and bilateral carotid occlusion. Rats were anesthetized with 1.4% isoflurane or fentanyl (25 microg x kg(-1) x h(-1)) and 70% nitrous oxide, with or without preischemic trimethaphan (2.5 mg given intravenously). In experiment 1, arterial plasma catecholamine concentrations were measured before, at 2 and 8 min during, and after ischemia (n = 5-8). In experiment 2, animals (n = 15) underwent histologic analysis 5 days after ischemia.
In experiment 1, intraischemic increases in plasma norepinephrine and epinephrine levels were 28 and 12 times greater in the fentanyl-nitrous oxide group than in the isoflurane group (P<0.01). Trimethaphan blocked all changes in plasma catecholamine concentrations (P<0.02). In experiment 2, isoflurane reduced the mean +/- SD percentage of dead hippocampal CA1 neurons compared with fentanyl-nitrous oxide (43+/-22% vs. 87+/-10%; P<0.001). Trimethaphan abolished the beneficial effects of isoflurane (91+/-6%; P<0.001). Similar observations were made in the cortex.
Isoflurane attenuated the peripheral sympathetic response to ischemia and improved histologic outcome compared with fentanyl and nitrous oxide. This outcome benefit was reversed by sympathetic ganglionic blockade. The beneficial effects of isoflurane may result from a neuroprotective influence of an intermediate sympathetic response that is abolished by trimethaphan.
与用芬太尼和氧化亚氮麻醉的大鼠相比，异氟烷麻醉的大鼠在全脑缺血后有更好的预后。作者想要确定循环儿茶酚胺浓度是否取决于麻醉剂，以及交感神经节阻断是否会影响麻醉介导的近乎完全性前脑缺血预后差异。
在两项不同的实验中，将禁食的正常体温的Sprague-Dawley大鼠分为四组之一，并使其平均动脉压维持在30 mmHg 10分钟，同时进行双侧颈动脉闭塞。大鼠用1.4%异氟烷或芬太尼（25微克·千克⁻¹·小时⁻¹）和70%氧化亚氮麻醉，有或没有缺血前静脉注射三甲噻方（2.5毫克）。在实验1中，在缺血前、缺血期间2分钟和8分钟以及缺血后测量动脉血浆儿茶酚胺浓度（n = 5 - 8）。在实验2中，动物（n = 15）在缺血后5天进行组织学分析。
在实验1中，芬太尼 - 氧化亚氮组缺血期间血浆去甲肾上腺素和肾上腺素水平的升高分别比异氟烷组高28倍和12倍（P<0.01）。三甲噻方阻断了血浆儿茶酚胺浓度的所有变化（P<0.02）。在实验2中，与芬太尼 - 氧化亚氮相比，异氟烷降低了海马CA1区死亡神经元的平均±标准差百分比（43±22%对87±10%；P<0.001）。三甲噻方消除了异氟烷的有益作用（91±6%；P<0.001）。在皮质也有类似的观察结果。
与芬太尼和氧化亚氮相比，异氟烷减弱了对缺血的外周交感反应并改善了组织学预后。这种预后益处被交感神经节阻断所逆转。异氟烷的有益作用可能源于三甲噻方所消除的适度交感反应的神经保护作用。
