Molecular actions of anesthetic drugs : Differential modulation by polymorphic forms of protein kinase C.

本研究是根据1993年Nature，364：82报道的麻醉药抑制中枢神经组织中PKC活性的文章而设计的。为了研究麻醉药物的分子作用，我们首先尝试建立了体外PKC检测系统。由于PKC亚类在脑组织中的差异表达在其他地方有报道，因此通过使用完善的cDNA表达系统来检查PKC亚类对麻醉药物的反应性。与我们的估计相反，我们在第一次体外实验中无法获得可重复的PKC活性结果。我们也不能有任何的氟烷抑制PKC活性，虽然有报道说，神经细胞中的PKC活性被氟烷抑制。本文认为以下几个因素可能是我们的方法失败的原因：1.体外实验系统和体内实验系统麻醉药物作用的差异：我们首先参考的报告， ...更多信息 本研究的一项研究表明，在体内，在与麻醉药物平衡的神经系统中，PKC活性被抑制，并且报告没有显示药物直接影响神经细胞中PKC活性。报告中的结果可能是对体内复杂神经元网络的最终影响。2.药物敏感性和/或信号转导系统的差异可能具有细胞系和/或种属的特异性：尽管有报道麻醉药物抑制神经细胞中的PKC活性，但我们在本研究中使用的COS 7细胞不是神经细胞，而是猴肾细胞。因此，大鼠/人神经细胞和猴肾细胞在细胞谱系和种属上可能存在很大差异。这种差异可能会在两个谱系之间引入一些不同的细胞内信号传导或药物敏感性。从上述可能性中，我们注意到体外方法的困难，然后我们同时进行了体内方法。实际上，PKC活性在戊巴比妥、氟烷或七氟醚麻醉的大鼠脑组织提取物中进行了检测。然而，与以前的报道不同，我们在大鼠脑组织中没有发现氟烷抑制PKC活性。在我们的在体实验中，氟烷增强了大鼠脑PKC活性。另一方面，七氟烷抑制大鼠PKC活性。少

This study was made a plan according to the paper (Nature, 364 : 82,1993) which reported that anesthetic drugs suppressed PKC activities in central nervous tissues. We tried at first to establish an in vitro PKC assay system in order to analyze molecular actions of anesthetic drugs. Since differential expressions of PKC subclasses in brain tissues were reported elsewhere, responsibility of PKC subclasses to anesthetic drugs were examined by using a well-established cDNA expression system. Contrary to our estimation, we could not have reproducible results on PKC activities in the first in vitro experiment. We also could not have any PKC suppression by halothane although it was reported that PKC activity in nerve cells was suppressed by halothane. The following factors are considered to possible reasons why our approach failed.1.Difference in anesthetic drug effects between on in vitro experimental system and on in vivo experimental system :The report which we first referred to make a pl … More an of this study showed that PKC activity was suppressed in vivo in nervous system equilibrated with anesthetic drugs and the report did not show that the drugs affected directly on PKC activity in nerve cells. It is possible that the results in the report were final effects on an in vivo complex neuron network. The difference between in vivo study and in vitro study may be the reason why no PKC suppression was found in COS7 cell lines which were used for in vitro cDNA expression experiment.2.Difference between drug sensitivity and/or signal transduction systems which may be specific to cell-lineage and/or species :Although the anesthetic drugs were reported to suppress PKC activities in nerve cells, the COS7 cell we used in this study is not a nerve cell but a monkey renal cell. Therefore, there could be much difference in cell-lineage and species between rat/human nerve cell and monkey renal cell. This difference might introduce some differential intracellular signaling or drug-sensitivity between two lineages.From those possibilities described above, we noticed a difficulty in our in vitro approach and then we performed an in vivo approach simultaneously too. Actually PKC activities were examined in brain tissue extracts from the rats which were anesthetized with nembutal, halothane, or sevoflurane. Unlike the previous report, however, we could not find any suppressed PKC activity by halothane in the rat brain tissues. Rat brain PKC activity in our in vivo experiment was enhanced by halothane. On the other hand, sevoflurane suppressed rat PKC activity. Less