Vascular Endothelium - Tissue Functioning and Remodeling in the Circulatory and Ventilatory Systems - page 573

Table 9.30. Mechanotransduction in cultured endothelial cells. Order of magnitude of response
time (Sources: [ 1086 , 1089 ]; IP 3 : inositol (1,4,5)-trisphosphate; LDL: low-density lipoprotein; NO:
nitric oxide; PDGF: platelet-derived growth factor; PGf2 α : prostaglandin-F2 α ; PGi2: prostacyclin;

SAC: stretch-activated channel; tPA: tissue plasminogen activator).

Target Ti m e

K + channel

O (ms)

SAC

Ca 2 + ]

[

O (s)

i

NO

IP 3 O (10 s)

Adenylate cyclase

O (mn)

PGi2, PGf2 α

PDGF Hours

Endithelin
tPA
Pinocytosis
Cell proliferation
Cytoskeleton alignment

Fibronectin Day

LDL metabolism
Cell alignment

Collagen Days

Cell growth

Cross variations in wall curvature that are observed in collapsed tubes of uniform
cross-section, due to wall transverse bending, induce transverse gradient of the WSS
axial component [ 1090 , 1091 ].
Many investigations have been carried out to explore either cell rheology
or behavior of mechanical stress-subjected cells. Flow chambers coated with a
homogeneous confluent monolayer of EC cultures are used for EC exposure to
laminar-flow stresses [ 1092 - 1095 ]. A special flow chamber has been designed to
expose endothelial cells to a given field of hemodynamic stresses that generates
2 forces applied at the cell inertia center: (1) a shear force that stretches the cell in
the streamwise direction, e.g., the force arising from the shear stress at the cell
inertia center; and (2) a shear torque that twists the cell perpendicularly to the cell
plane, induced by the WSS transverse gradient (WSSTG) [ 1096 ]. Four regions of
the wetted cell culture were defined by these investigators: (1) region I near the
contact point where both WSS and WSSTG are small; (2) region II of low velocity
flow where WSS is low but WSSTG is significant; (3) region III with a change
in wall curvature sign where both WSS and WSSTG are great; and (4) region IV,
where WSS reaches its highest values but WSSTG is small. These authors discussed
the role of torsion in the EC detachment both from the wall of the flow chamber