Cromer J A, Bennett P B, Hunter W L, Zinn D
Undersea Biomed Res. 1979 Dec;6(4):367-77.
This study compares the effects of various so-called trimix mixtures (10, 20, and 40% N2 in He-O2) on the convulsion threshold pressure (Pc) and EEG activity in 60 adult male Wistar rats with chronically implanted electrodes with those in 20 rats in He-O2 only. Restrained animals were individually compressed with trimix mixtures at 80 or 160 atm per hour to a simulated depth of 138 ATA; colonic temperature was maintained at normal levels. Pc was defined as the initial occurrence of overt sustained generalized tonic-clonic seizures, accompanied by typical "spike and wave" patterns in all EEG leads. As in man, in rats trimix increased the depth of the onset of HPNS tremors and myoclonic jerks in all six groups of rats. However, the Pc of the trimix groups was no different from the Pc of the helium-oxygen group (113 ATA), and at 40% N2, rats showed EEG seizures but no overt convulsions. These results are discussed in relation to those of other studies showing the extension of Pc in mice and monkeys attained by adding narcotics to heliox; the paper also considers the relevance of method of compression, addition of nitrogen, core temperature, and species differences, as well as the need for EEG measurements and direct observation of overt convulsions as indicators of an effective antagonism of HPNS.
本研究比较了各种所谓的三混气混合物（氦氧混合气中含10%、20%和40%氮气）对60只成年雄性Wistar大鼠惊厥阈值压力（Pc）和脑电图活动的影响，这些大鼠长期植入电极，同时与仅暴露于氦氧混合气的20只大鼠进行比较。将受约束的动物分别以每小时80或160个大气压的三混气混合物进行压缩，模拟深度达138ATA；结肠温度维持在正常水平。Pc定义为首次出现明显的持续性全身性强直阵挛性癫痫发作，并伴有所有脑电图导联典型的“棘波和慢波”模式。与人类一样，在所有六组大鼠中，三混气均增加了高压神经综合征震颤和肌阵挛性抽搐发作的深度。然而，三混气组的Pc与氦氧组（113ATA）的Pc并无差异，且在氮气含量为40%时，大鼠出现脑电图癫痫发作，但无明显惊厥。结合其他研究结果对这些结果进行了讨论，其他研究表明，通过在氦氧混合气中添加麻醉剂可提高小鼠和猴子的Pc；本文还考虑了压缩方法、添加氮气、核心温度和物种差异的相关性，以及脑电图测量和直接观察明显惊厥作为高压神经综合征有效拮抗指标的必要性。
