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Logo of bmcbiophysBioMed CentralBiomed Central Web Sitesearchsubmit a manuscriptregisterthis articleBMC BiophysicsJournal Front Page
 
BMC Biophys. 2012; 5: 5.
Published online Mar 24, 2012. doi:  10.1186/2046-1682-5-5
PMCID: PMC3359235
Fluorescence anisotropy of diphenylhexatriene and its cationic Trimethylamino derivative in liquid dipalmitoylphosphatidylcholine liposomes: opposing responses to isoflurane
Steven C Nelson,1,3 Steven K Neeley,1,4 Eric D Melonakos,1,5 John D Bell,1,6 and David D Busathcorresponding author2
1Department of Physiology and Developmental Biology, Brigham Young University, Provo, UT 84602 USA
2WIDB 574, Dept. of Physiology and Developmental Biology, Brigham Young University, Provo, UT 84602, USA
3The University of Toledo College of Medicine, 3045 Arlington Avenue, Mail Stop 1043, Toledo, OH 43614, USA
4University of Texas Southwestern, 5323 Harry Hines Blvd., Dallas, TX 75390-9003, USA
5Dept. of Bioengineering, Univ. of Utah, Salt Lake City, UT 84112, USA
6Dean of Undergraduate Education, Brigham Young University, Provo, UT 84602, USA
corresponding authorCorresponding author.
Steven C Nelson: steven.nelson/at/rockets.utoledo.edu; Steven K Neeley: steven.neeley/at/utsouthwestern.edu; Eric D Melonakos: eric.melonakos/at/utah.edu; John D Bell: john_bell/at/byu.edu; David D Busath: david_busath/at/byu.edu
Received July 14, 2011; Accepted March 24, 2012.
Abstract
Background
The mechanism of action of volatile general anesthetics has not yet been resolved. In order to identify the effects of isoflurane on the membrane, we measured the steady-state anisotropy of two fluorescent probes that reside at different depths. Incorporation of anesthetic was confirmed by shifting of the main phase transition temperature.
Results
In liquid crystalline dipalmitoylphosphatidylcholine liposomes, isoflurane (7-25 mM in the bath) increases trimethylammonium-diphenylhexatriene fluorescence anisotropy by ~0.02 units and decreases diphenylhexatriene anisotropy by the same amount.
Conclusions
The anisotropy data suggest that isoflurane decreases non-axial dye mobility in the headgroup region, while increasing it in the tail region. We propose that these results reflect changes in the lateral pressure profile of the membrane.
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