Biomedical Engineering Reference
In-Depth Information
Table 9.13.
Chloride and sodium channels of endothelial cells (Sources: [
895
,
896
]; CFTR: cystic
fibrosis transmembrane conductance regulator channel). Chloride channels prevent hyperpolariza-
tion. Volume-regulated anion channels (VRAC) are associated with RhoA activation that restricts
the endothelial barrier function. They favors endothelial cell growth and angiogenesis.
Ion carriers
Features
Chloride channels
Ca
2
+
-activated
EC type-dependent effect on
Cl
−
channels (CaCC)
membrane potential
High-conductance
Activation by
β
-adrenergic stimuli
Cl
−
channels
Volume-regulated
Activation by shear and stretch;
anion channels (VRAC)
participation of annexin, caveolin-1, and RhoA;
mechanosensor;
role in endothelium growth and angiogenesis;
decrease intracellular pH
CFTR
Reduction in VRAC and CaCC activity
Shear stress-activated
Sustained membrane depolarization
Cl
−
channels
Sodium channels
Amiloride-sensitive
Microvascular endothelium
Na
V
1
Shear stress sensitivity;
ERK1/2 activation
Na
+
-K
+
ATPase
Resting potential
Na
+
-Ca
2
+
exchanger
Ca
2
+
flux
flows increase [Ca
2
+
]
i
, with response dynamics that depend on the flow pattern
[
899
]. The release of the substances active on vasomotor tone depends on shear
stress applied on the endothelium (Sect.
9.10
). Shear stress might also regulate
the secretion of molecules involved in coagulation and fibrinolysis or inhibiting
thrombosis (Sect.
9.8
). High wall shear stress hinders leukocyte adhesion on the
endothelium (Sect.
9.7
). The endothelium adapts the vessel wall to the local flow
pattern (Sect.
7.11
).
A set of signaling messengers and mediators that involves 2 secreted molecules,
PDGFbb and TGF
1, and 4 other proteins, lamin-A, lysyl oxidase, ERK1, and
ERK2, contributes to the response of cultured vascular endothelial cells according to
the magnitude of applied mechanical stress [
900
]. Factor PDGFbb that acts on both
β
+
/−
4N/m
2
), and oscillatory shear stress (
+
/−
2N/m
2
),
with a high unsteady component (2
using few flow frequencies (0.4, 1, and 2 Hz).
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