Membrane lipid order of human red cells is altered by physiological
levels of hydrostatic pressure.
Barshtein, Gregory, Lev Bergelson, Arie Dagan, Enrico Gratton, and
Saul Yedgar.
Department of Biochemistry, Hebrew University - Hadassah Medical
School, Dept. of Pharmacy, The Hebrew University School of Pharmacy,
Jerusalem, Israel 91120 and Laboratory of Fluorescence Dynamics,
Department of Physics, University of Illinois at Urbana-Champaign,
Urbana, Illinois 61801
APStracts 3:0393H, 1996.
The effect of hydrostatic pressure at levels applied in diving or
hyperbaric treatment (thus considered "physiological") on the
order of lipid domains in human red blood cell (RBC) membrane was
studied. Membrane order was determined by measuring: 1. Fluorescence
anisotropy (FAn) of lipid probes; 2. Resonance energy transfer (RET)
from tryptophan to lipid probes; 3. Spectral shifts in Laurdan
fluorescence emission. It was found that application of mild pressure
(<15 atmospheres): 1. Increased, selectively, the FAn of lipid
probes which monitor the membrane lipid core; 2. Increased tryptophan
FAn; 3. Increased the RET from tryptophan to lipid probes residing in
the lipid core; 4. Induced changes in Laurdan fluorescence spectrum,
which correspond to reduced membrane hydration. It is proposed that
application of pressure of several atmospheres increases the phase
order of membrane lipid domains particularly in the proximity of
proteins. Since membrane lipid order ("fluidity") of RBC
plays an important role in their cellular and rheological functions,
the pressure-induced alterations of the RBC membrane might be
pertinent to microcirculatory disorders observed in humans subjected
to elevated pressure.
Received 20 May 1996; accepted in final form 29 August 1996.
APS Manuscript Number H458-6.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 7 October 1996