About this Research Topic
The transport of oxygen and other nutrients to the tissues and organs is dependent on interactions between the flowing blood and its various components with the vasculature. These interactions and how they affect the vasculature and physiological function are addressed in this Research Topic.
Flowing blood affects the vasculature by changes in shear stress generated by laminar, oscillatory or disturbed flow. A process called mechanotransduction describes how the mechanical stimuli of the flowing blood are translated into biochemical signals generated in the vasculature that affect function. Many of these biochemical stimuli are redox sensitive and involve changes in the production of reactive oxygen species. There are also effects on nitric oxide (NO) production and release of Ca2+, both of which have important physiological effects.
The major cellular component of blood corresponding to ~ 95% of the cells present is the red blood cells (RBCs) responsible for oxygn tranport. However effective oxygen transport requires more than the reversible binding of oxygen to Hb. The RBCs tend to aggregate and concentrate along the central axis of the blood vessels resulting in a cell free layer (CFL) adjacent to the vasculature. The transport of oxygen from RBCs to the tissues, therefore, involves diffusion across the CFL and is modulated by changes in the thickness of the CFL.
Effective oxygen transport also requires the evaluation of secondary RBC reactions associated with oxidative stress. Minimized oxidative stress is necessary to limit oxidation of Hb, which affects oxygen binding, and oxidative damage to the membrane, which impairs deformability. RBC oxidative stress is triggered by the autoxidation of oxygen bound to Hb resulting in the formation of superoxide which initiates a cascade of oxidative reactions that affect the RBC and can even transfer reactive oxygen species to the vasculature inducing an inflammatory response.
Vascular tone and dilatation are, for the most part, regulated by NO produced by endothelial nitric oxide synthase (NOS). However, under conditions of reduced NOS activity resulting from impaired vascular function and or reduced partial pressure of oxygen, the RBC can contribute to the maintenance of the required vascular tone. This role of the RBC in maintaining vascular tone is related to the formation of NO by RBC NOS and the reduction of plasma nitrite to NO coupled to a mechanism for the transfer of NO from the RBC to the vasculature.
The various types of leukocytes in the blood are involved in protecting the body against infectious disease and foreign invaders and the platelets are involved in blood clotting.
The leukocytes tend to roll along the surface of the vasculature and together with the platelets adhere to the vasculature, particularly during an inflammatory response eventually resulting in thrombotic vascular occlusion and transmigration of the leukocytes to inflamed tissue.
This Research Topic summarizes affects on the vasculature originating from flow as well as interactions of the various blood components with the vasculature. This Research topic, thus, provides important insights in understanding vascular function and oxygen transport.
Keywords: vasculature, blood flow, oxidative stress, nitric oxide, red blood cells
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