title: Autoregulation and mechanotransduction control the arteriolar response to small changes in hematocrit.
abstract: Here, we present an analytic model of arteriolar mechanics that accounts for key autoregulation mechanisms, including the myogenic response and the vasodilatory effects of nitric oxide (NO) in the vasculature. It couples the fluid mechanics of blood flow in arterioles with solid mechanics of the vessel wall and includes the effects of wall shear stress- and stretch-induced endothelial NO production. The model can be used to describe the regulation of blood flow and NO transport under small changes in hematocrit and to analyze the regulatory response of arterioles to small changes in hematocrit. Our analysis revealed that the experimentally observed paradoxical increase in cardiac output with small increases in hematocrit results from the combination of increased NO production and the effects of a strong myogenic response modulated by elevated levels of WSS. Our findings support the hypothesis that vascular resistance varies inversely with blood viscosity for small changes in hematocrit in a healthy circulation that responds to shear stress stimuli. They also suggest beneficial effects independent of changes in O(2) carrying capacity associated with the postsurgical transfusion of one or two units of blood.
authors.affiliation: Department of Mechanical and Aerospace Engineering, University of California-San Diego, La Jolla, California 92093-0412, USA.
authors.forename: Krishna
authors.initials: K
authors.lastname: Sriram
authors.forename: Beatriz Y
authors.initials: BY
authors.lastname: Salazar Vázquez
authors.forename: Amy G
authors.initials: AG
authors.lastname: Tsai
authors.forename: Pedro
authors.initials: P
authors.lastname: Cabrales
authors.forename: Marcos
authors.initials: M
authors.lastname: Intaglietta
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Tartakovsky
mesh_terms: D001160:Arterioles / Q000166:cytology / Q000502:physiology*; D001809:Blood Viscosity / Q000502:physiology; D002302:Cardiac Output / Q000502:physiology; D003198:Computer Simulation; D006400:Hematocrit; D006706:Homeostasis / Q000502:physiology*; D006801:Humans; D040542:Mechanotransduction, Cellular / Q000502:physiology*; D008955:Models, Cardiovascular; D008962:Models, Theoretical; D009569:Nitric Oxide / Q000502:physiology; D012039:Regional Blood Flow / Q000502:physiology; D013314:Stress, Mechanical; D014655:Vascular Resistance / Q000502:physiology; D014664:Vasodilation / Q000502:physiology
chemical_list: D009569:Nitric Oxide