Homma Yuko, Teneud Luis, Skinner Robert D, Williams Keith, Garcia-Rill Edgar
Department of Anatomy, University of Arkansas for Medical Sciences, 4301 W. Markham Street, Little Rock, AR 72205, USA.
Brain Res Bull. 2003 Jul 15;61(2):189-96. doi: 10.1016/s0361-9230(03)00116-3.
Propofol (2,6-diisopropylphenol) is a widely used anesthetic agent, but its mechanisms of action are poorly understood. In this report, the effects of three dose levels of propofol (5, 7.5, and 10mg/kg) on the amplitude of the vertex-recorded, sleep state-dependent P13 midlatency evoked potential were investigated. The P13 potential is generated, at least in part, by the ascending cholinergic reticular activating system (RAS). The RAS is known to be affected by anesthetic agents. Intravenous injections of propofol were found to reduce the amplitude of the P13 potential in a dose- and time-dependent manner. At 2min post-injection, the mean P13 amplitude was suppressed to 40% of its pre-injection level by the lowest dose, but was suppressed to 10% of pre-injection levels by the two higher doses of propofol. The duration of the suppression of mean P13 potential amplitude was also dose-dependent such that complete recovery occurred by 5min using 5mg/kg, by 15min using 7.5mg/kg and by 30min using 10mg/kg of propofol. Using a paired stimulus paradigm, transient effects on habituation of the P13 potential were observed but only after the highest dose. Thus, one of the mechanisms of propofol may be to affect portions of the RAS which modulate the level of arousal. It may only transiently affect higher systems known to modulate the degree of habituation of responses by the RAS (i.e. processes which modulate habituation and may participate in sensory gating and distractibility).
丙泊酚（2,6 - 二异丙基苯酚）是一种广泛使用的麻醉剂，但其作用机制尚不清楚。在本报告中，研究了三种剂量水平的丙泊酚（5、7.5和10mg/kg）对顶点记录的、睡眠状态依赖性P13中潜伏期诱发电位幅度的影响。P13电位至少部分是由胆碱能网状上行激活系统（RAS）产生的。已知RAS会受到麻醉剂的影响。静脉注射丙泊酚后，发现其以剂量和时间依赖性方式降低P13电位的幅度。注射后2分钟，最低剂量可将平均P13幅度抑制至注射前水平的40%，但较高的两种剂量可将其抑制至注射前水平的10%。平均P13电位幅度抑制的持续时间也呈剂量依赖性，使用5mg/kg丙泊酚时5分钟完全恢复，使用7.5mg/kg时15分钟完全恢复，使用10mg/kg时30分钟完全恢复。使用配对刺激范式，仅在最高剂量后观察到对P13电位习惯化的短暂影响。因此，丙泊酚的作用机制之一可能是影响RAS中调节觉醒水平的部分。它可能仅短暂影响已知调节RAS反应习惯化程度的高级系统（即调节习惯化并可能参与感觉门控和注意力分散的过程）。
