What is endothelial shear stress?
Endothelial shear stress is the tangential stress due to the friction of the flowing blood on the endothelial surface of the arterial wall (Figure 2). 32,33. It is expressed in units of force per unit area (Newtons per square metre or Pascals or dynes per square centimetre; 1 N/m2 = 1 Pa = 10 dyn/cm2).
What causes shear stress in blood vessels?
Shear stress is caused by the flow of fluid across the surface and its value is directly proportional to the velocity of the surrounding fluid [38]. With the lack of sensors, shear stress could only be approximated with use of CFD techniques.
How does shear stress induce endothelial and vascular injury?
Shear stress induces eNOS transcription and translation and thus results in greater availability of nitric oxide. Human and animal model studies have demonstrated that regular, moderate exercise can reverse systemic endothelial dysfunction via changes in cardiac output16 and possibly altered pulsatility.
How does shear stress cause atherosclerosis?
Disturbed shear stress also influences the site selectivity of atherosclerotic plaque formation as well as its associated vessel wall remodeling, which can affect plaque vulnerability, stent restenosis and smooth muscle cell intimal hyperplasia in venous bypass grafts.
How does Wall shear affect endothelial cells?
High shear stress, as found in laminar flow, promotes endothelial cell survival and quiescence, alignment in the direction of flow, and secretion of substances that promote vasodilation and anticoagulation.
How does shear stress affect cells?
The Impact of Flow/Shear Stress on Cells This mechanical stimulus has a great impact on the physiological behavior and adhesion properties of cells. Cells react to shear stress by changes in ion channel activation, gene expression, and reorganization of the whole cell layer.
How does shear stress affect blood vessels?
Low shear stress, or changing shear stress direction as found in turbulent flow, promotes endothelial proliferation and apoptosis, shape change, and secretion of substances that promote vasoconstriction, coagulation, and platelet aggregation.
What happens when endothelial cells are injured?
Endothelial cells exposed to inflammatory stimuli from the circulation or the microenvironment exhibit impaired vascular tone, increased permeability, elevated procoagulant activity, and dysregulated vascular formation, collectively contributing to the development of vascular diseases.
How do endothelial cells control vasoconstriction?
Activation of ET-B1 receptors on the endothelium causes vasodilatation by inducing the release of NO and PGI2 [73, 74]. In ED, ET-B1 receptors on the endothelial cells are downregulated, while ET-B2 receptors on smooth muscle cells are upregulated, thus enhancing vasoconstriction [75, 76].
Are endothelial cells smooth muscle?
Two essential cell types in blood vessels are endothelial cells (ECs), which line the inside of all blood vessels, and vascular smooth muscle cells (VSMCs), which regulate vessel stability.