2-(3-Methyl-3<i>H</i>-diaziren-3-yl)ethyl 1-(1-phenylethyl)-1<i>H</i>-imidazole-5-carboxylate: A Derivative of the Stereoselective General Anesthetic Etomidate for Photolabeling Ligand-Gated Ion Channels
作者:S. Shaukat Husain、Michael R. Ziebell、Dirk Ruesch、Filbert Hong、Enrique Arevalo、Jonathan A. Kosterlitz、Richard W. Olsen、Stuart A. Forman、Jonathan B. Cohen、Keith W. Miller
DOI:10.1021/jm020465v
日期:2003.3.1
To locate general anesthetic binding sites on ligand-gated ion channels, a diazirine derivative of the potent intravenous anesthetic, R-(+)-etomidate (2-ethyl 1-(1-phenylethyl)-1H-imidazole-5-carboxylate), has been synthesized and characterized. R-(+)-Azietomidate [2-(3-methyl-3H-diaziren-3-yl)ethyl 1-(l-phenylethyl)-1H-imidazole-5-carboxylate] anesthetizes tadpoles with an EC50 of 2.2 muM, identical to that of R-(+)-etomidate. At this concentration both agents equally enhanced GABA-induced currents and decreased binding of the caged-convulsant [S-35]TBPS to GABA(A) receptors. In all of the above actions R-(+)-azietomidate is about an order of magnitude more potent than S-(-)-azietomidate, an enantioselectivity comparable to etomidate's. R-(+)-Azietomidate also inhibits acetylcholine-induced currents in nicotinic acetylcholine receptors, with about twice the potency of the parent compound. [H-3]Azietomidate photoincorporated into Torpedo nicotinic acetylcholine receptor-rich membranes. Desensitization decreased photoincorporation into the delta-subunit and increased that into the alpha-subunit. The latter increase was confined to a proteolytic fragment containing the first three transmembrane segments. Thus, R-(+)-azietomidate is a potent stereoselective general anesthetic and an effective photolabel.