title: Fluorescence anisotropy of diphenylhexatriene and its cationic Trimethylamino derivative in liquid dipalmitoylphosphatidylcholine liposomes: opposing responses to isoflurane.
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.
authors.affiliation: WIDB 574, Dept, of Physiology and Developmental Biology, Brigham Young University, Provo, UT 84602, USA. david_busath@byu.edu.
authors.forename: Steven C
authors.initials: SC
authors.lastname: Nelson
authors.forename: Steven K
authors.initials: SK
authors.lastname: Neeley
authors.forename: Eric D
authors.initials: ED
authors.lastname: Melonakos
authors.forename: John D
authors.initials: JD
authors.lastname: Bell
authors.forename: David D
authors.initials: DD
authors.lastname: Busath