Durieux M E
Department of Anesthesiology, University of Virginia, Charlottesville 22908.
Anesthesiology. 1995 Jan;82(1):174-82. doi: 10.1097/00000542-199501000-00022.
Interactions between volatile anesthetics and muscarinic acetylcholine receptors have been studied primarily in binding assays or in functional systems derived from tissues or cells, often containing multiple receptor subtypes. Because interactions with muscarinic signaling systems may explain some effects and side effects of anesthetics and form a model for anesthetic-protein interactions in general, the author studied anesthetic inhibition of muscarinic signaling in an isolated system.
mRNA encoding the m1 muscarinic receptor subtype was prepared in vitro and expressed in Xenopus oocytes. Effects of halothane on methylcholine-induced intracellular Ca2+ release was measured. Angiotensin II receptors were expressed to evaluate anesthetic effects on intracellular signaling.
m1 Receptors expressed in oocytes were functional, and could be inhibited by atropine and pirenzepine. Halothane depressed m1 muscarinic signaling in a dose-dependent manner: half-maximal inhibition of 10(-7) M methylcholine was obtained with 0.3 mM halothane. The effect was reversible and could be overcome by high concentrations of muscarinic agonist. Angiotensin II signaling was unaffected by 0.34 mM halothane.
m1 Muscarinic signaling is inhibited by halothane, and lack of halothane effect on angiotensin signaling indicates that the intracellular signaling systems of Xenopus oocytes are unaffected. Therefore, the most likely site of halothane action is the receptor and/or G protein. Oocytes provide a versatile system for detailed investigation into the molecular mechanism of anesthetic-protein interactions.
挥发性麻醉剂与毒蕈碱型乙酰胆碱受体之间的相互作用主要在结合试验或源自组织或细胞的功能系统中进行研究，这些系统通常包含多种受体亚型。由于与毒蕈碱信号系统的相互作用可能解释麻醉剂的一些作用和副作用，并总体上形成麻醉剂 - 蛋白质相互作用的模型，作者在一个分离的系统中研究了麻醉剂对毒蕈碱信号的抑制作用。
体外制备编码m1毒蕈碱受体亚型的mRNA，并在非洲爪蟾卵母细胞中表达。测量氟烷对甲胆碱诱导的细胞内Ca2 +释放的影响。表达血管紧张素II受体以评估麻醉剂对细胞内信号传导的作用。
在卵母细胞中表达的m1受体具有功能，并且可被阿托品和哌仑西平抑制。氟烷以剂量依赖性方式抑制m1毒蕈碱信号传导：0.3 mM氟烷可使10（-7）M甲胆碱的半数最大抑制率达到。该作用是可逆的，并且可被高浓度的毒蕈碱激动剂克服。0.34 mM氟烷对血管紧张素II信号传导无影响。
氟烷抑制m1毒蕈碱信号传导，并且氟烷对血管紧张素信号传导无影响表明非洲爪蟾卵母细胞的细胞内信号系统未受影响。因此，氟烷作用的最可能部位是受体和/或G蛋白。卵母细胞为详细研究麻醉剂 - 蛋白质相互作用的分子机制提供了一个通用系统。
