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Shear stress induces a time- and position-dependent increase in endothelial cell membrane fluidity
P J Butler1, G Norwich, S Weinbaum
1The Whitaker Institute of Biomedical Engineering and Department of Bioengineering, University of California-San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0427, USA.
American Journal of Physiology. Cell Physiology
|March 14, 2001
Summary
Shear stress rapidly alters endothelial cell membrane fluidity, with distinct upstream and downstream changes that are time-dependent. These findings reveal spatial heterogeneity in membrane response to blood flow.
Area of Science:
- Biophysics
- Cell Biology
- Fluid Mechanics
Background:
- Blood flow exerts shear stress on endothelial cells, potentially influencing cellular functions via plasma membrane alterations.
- Understanding the dynamic response of membrane lipid fluidity to shear stress is crucial for elucidating mechanotransduction pathways.
Purpose of the Study:
- To quantify the spatial and temporal effects of shear stress on the lipid fluidity of endothelial cell plasma membranes.
- To investigate how varying levels of shear stress impact membrane fluidity dynamics over time.
Main Methods:
- Utilized a flow chamber to apply controlled shear stress (tau) to bovine aortic endothelial cells.
- Employed fluorescence recovery after photobleaching with 1,1'-dihexadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate [DiIC(16)(13)] to measure the DiI diffusion coefficient (D), a marker of lipid fluidity.
- Measured D on both upstream and downstream sides of cells under static, dynamic shear stress, and post-cessation conditions.
Main Results:
- A shear stress of 10 dyn/cm(2) induced a rapid (<10 s) transient increase in upstream membrane fluidity and a decrease downstream, with significant spatial differences.
- A secondary, larger increase in upstream fluidity peaked at 7 minutes, while downstream fluidity showed minimal secondary changes.
- Higher shear stress (20 dyn/cm(2)) initially increased fluidity at both sites, but led to significantly higher upstream fluidity by 30 seconds to 1 minute.
Conclusions:
- Shear stress induces time-dependent and spatially heterogeneous changes in endothelial cell membrane lipid fluidity.
- These dynamic alterations in membrane fluidity may play a significant role in shear-induced modulation of membrane proteins and cellular responses.