title: Retinal oxygen distribution and the role of neuroglobin.
abstract: The retina is the tissue layer at the back of the eye that is responsible for light detection. Whilst equipped with a rich supply of oxygen, it has one of the highest oxygen demands of any tissue in the body and, as such, supply and demand are finely balanced. It has been suggested that the protein neuroglobin (Ngb), which is found in high concentrations within the retina, may help to maintain an adequate supply of oxygen via the processes of transport and storage. We construct mathematical models, formulated as systems of reaction-diffusion equations in one-dimension, to test this hypothesis. Numerical simulations show that Ngb may play an important role in oxygen transport, but not in storage. Our models predict that the retina is most susceptible to hypoxia in the regions of the photoreceptor inner segment and inner plexiform layers, where Ngb has the potential to prevent hypoxia and increase oxygen uptake by 30-40 %. Analysis of a simplified model confirms the utility of Ngb in transport and shows that its oxygen affinity ([Formula: see text] value) is near optimal for this process. Lastly, asymptotic analysis enables us to identify conditions under which the piecewise linear and quadratic approximations to the retinal oxygen profile, used in the literature, are valid.
authors.affiliation: Mathematical Institute, University of Oxford, Andrew Wiles Building, Radcliffe Observatory Quarter, Woodstock Road, Oxford, OX2 6GG, UK. p.a.roberts@univ.oxon.org.|Department of Computer Science, University of Oxford, Wolfson Building, Parks Road, Oxford, OX1 3QD, UK. p.a.roberts@univ.oxon.org.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Roberts
authors.affiliation: Wolfson Centre for Mathematical Biology, Mathematical Institute, University of Oxford, Andrew Wiles Building, Radcliffe Observatory Quarter, Woodstock Road, Oxford, OX2 6GG, UK.
authors.forename: Eamonn A
authors.initials: EA
authors.lastname: Gaffney
authors.affiliation: Institute of Ophthalmology, University College London, 11-43 Bath Street, London, EC1V 9EL, UK.
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Luthert
authors.affiliation: Department of Ophthalmology, Queen's Medical Centre, Derby Road, Nottingham, Nottinghamshire, NG7 2UH, UK.
authors.forename: Alexander J E
authors.initials: AJ
authors.lastname: Foss
authors.affiliation: Mathematical Institute, University of Oxford, Andrew Wiles Building, Radcliffe Observatory Quarter, Woodstock Road, Oxford, OX2 6GG, UK.|Department of Computer Science, University of Oxford, Wolfson Building, Parks Road, Oxford, OX1 3QD, UK.
authors.forename: Helen M
authors.initials: HM
authors.lastname: Byrne
mesh_terms: D003198:Computer Simulation; D005914:Globins / Q000378:metabolism*; D006801:Humans; D008954:Models, Biological; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D000078787:Neuroglobin; D010100:Oxygen / Q000378:metabolism*; D012160:Retina / Q000378:metabolism*
chemical_list: D009419:Nerve Tissue Proteins; D000078787:Neuroglobin; D005914:Globins; D010100:Oxygen
keywords: Asymptotics; Facilitated diffusion; Hypoxia; Oxygen transport; Reaction–diffusion equations