title: Age-related alterations in the diffusional transport of amino acids across the human Bruch's-choroid complex.
abstract: Photoreceptor maintenance is dependent on effective delivery of nutrients from the choroidal circulation by way of the acellular Bruch's membrane and the retinal pigment epithelium. Aging of Bruch's membrane is associated with thickening, increased cross linking of fibers, and deposition of debris culminating in reduced porosity. The present study has investigated the effects of aging on the diffusional transport of eight amino acids across Bruch's membrane in 19 human donors. Diffusion studies were carried out in Ussing chambers, and the amount of time-dependent transfer of amino acids across the preparation was quantified by reverse-phase high-performance liquid chromatography. Diffusion rates for all amino acids showed a significant linear decline with aging of donor. The importance of this reduction in delivery of amino acids is discussed with reference to both normal physiology and age-related macular degeneration.
authors.affiliation: Department of Ophthalmology, the Guy's, King's and St. Thomas' Hospitals Medical and Dental School, King's College London, United Kingdom. alyhussain@aol.com
authors.forename: Ali A
authors.initials: AA
authors.lastname: Hussain
authors.forename: Lisa
authors.initials: L
authors.lastname: Rowe
authors.forename: John
authors.initials: J
authors.lastname: Marshall
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000378:metabolism*; D000596:Amino Acids / Q000378:metabolism*; D001692:Biological Transport / Q000502:physiology; D016570:Bruch Membrane / Q000378:metabolism*; D002829:Choroid / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D004058:Diffusion; D006801:Humans; D008875:Middle Aged
chemical_list: D000596:Amino Acids