Identification of a fluorescent general anesthetic, 1-aminoanthracene
- Christopher A. Buttsa,
- Jin Xib,
- Grace Branniganc,
- Abdalla A. Saadd,
- Srinivasan P. Venkatachaland,
- Robert A. Pearced,
- Michael L. Kleinc,
- Roderic G. Eckenhoffb,1 and
- Ivan J. Dmochowskia,1
- aDepartment of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, PA 19104;
- bDepartment of Anesthesiology and Critical Care, University of Pennsylvania School of Medicine, 311A John Morgan Building, 3620 Hamilton Walk, Philadelphia, PA 19104;
- cCenter for Molecular Modeling, University of Pennsylvania, 231 South 34th Street, Philadelphia, PA 19104; and
- dDepartments of Anesthesiology and Physiology, University of Wisconsin, 601 Science Drive, Madison, WI 53711
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Edited by Elizabeth C. Theil, Children's Hospital Oakland Research Institute, Oakland, CA, and accepted by the Editorial Board March 4, 2009 (received for review October 21, 2008)
Abstract
We identified a fluorophore, 1-aminoanthracene (1-AMA), that is anesthetic, potentiates GABAergic transmission, and gives an appropriate dissociation constant, Kd ≈ 0.1 mM, for binding to the general anesthetic site in horse spleen apoferritin (HSAF). 1-AMA fluorescence is enhanced when bound to HSAF. Thus, displacement of 1-AMA from HSAF by other anesthetics attenuates the fluorescence signal and allows determination of Kd, as validated by isothermal titration calorimetry. This provides a unique fluorescence assay for compound screening and anesthetic discovery. Additional electrophysiology experiments in isolated cells indicate that 1-AMA potentiates chloride currents elicited by GABA, similar to many general anesthetics. Furthermore, 1-AMA reversibly immobilizes stage 45–50 Xenopus laevis tadpoles (EC50 = 16 μM) and fluorescence micrographs show 1-AMA localized to brain and olfactory regions. Thus, 1-AMA provides an unprecedented opportunity for studying general anesthetic distribution in vivo at the cellular and subcellular levels.
Footnotes
- 1To whom correspondence may be addressed. E-mail: roderic.eckenhoff{at}uphs.upenn.edu or ivandmo{at}sas.upenn.edu
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Author contributions: R.A.P., M.L.K., R.G.E., and I.J.D. designed research; C.A.B., J.X., G.B., A.A.S., S.P.V., R.G.E., and I.J.D. performed research; C.A.B., R.A.P., R.G.E., and I.J.D. analyzed data; and C.A.B., R.G.E., and I.J.D. wrote the paper.
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The authors declare no conflict of interest.
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This article is a PNAS Direct Submission. E.C.T. is a guest editor invited by the Editorial Board.
