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Computer simulations of oxygen transport by hemoglobin solutions with differing oxygen affinities in arteriolar‐sized, artificial vessels
Author(s) -
Cole Russell,
Baker Dale,
Vandegriff Kim,
Winslow Robert
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a409-a
Subject(s) - chemistry , oxygen , hemoglobin , oxygen transport , affinities , red blood cell , diffusion , biophysics , thermal diffusivity , biochemistry , thermodynamics , organic chemistry , physics , biology
Oxygen transport in blood flowing through an arteriole is characterized by an immobile hemoglobin (Hb) phase contained within erythrocytes and a plasma phase through which dissolved O 2 must diffuse to reach tissue. The dissolved O 2 gradients drive lateral O 2 transport, and the amount of O 2 in plasma is much smaller than the O 2 bound to Hb within red cells. Acellular Hb solutions, designed to subsidize O 2 supply during blood loss, have a variety of equilibrium O 2 binding properties and molecular diffusivities that are 5 50 times smaller than that of dissolved O 2 . Since acellular Hbs are used at concentrations 10–100 times larger than local dissolved O 2 concentrations, lateral O 2 transport is “facilitated” due to outward diffusion of oxyhemoglobin. Simulations of O 2 delivery in arteriolar‐sized, gas permeable tubes were performed for different Hb solutions to quantify the effect of facilitated diffusion by integrating radial HbO 2 fluxes. At a given [Hb], cell‐free Hbs deliver O 2 in a qualitatively different manner than an erythrocyte suspension at the same intracellular [Hb]. Hbs with low O 2 affinities (P50>16 mmHg) and larger diffusivities (D=10 −6 cm 2 /s) offload O 2 faster than blood at the same [Hb]. There is a small difference in O 2 offloading for Hbs with P50=16 or 33 mmHg. Hbs with higher oxygen affinity (P50<10 mmHg) and smaller diffusivity (D=10 −7 cm 2 /s) release O 2 slower than blood at the same [Hb]. The delivery of O 2 for a mixture containing high‐O 2 affinity, small‐diffusivity Hb and red cells is qualitatively similar to that of red cells alone.