Homeostasis in the vertebrate lens: mechanisms of solute exchange

Ralf Dahm, Jan van Marle, Roy A. Quinlan, Alan R. Prescott, Gijs F. J. M. Vrensen

    Research output: Contribution to journalReview articlepeer-review

    34 Citations (Scopus)

    Abstract

    The eye lens is avascular, deriving nutrients from the aqueous and vitreous humours. It is, however, unclear which mechanisms mediate the transfer of solutes between these humours and the lens' fibre cells (FCs). In this review, we integrate the published data with the previously unpublished ultrastructural, dye loading and magnetic resonance imaging results. The picture emerging is that solute transfer between the humours and the fibre mass is determined by four processes: (i) paracellular transport of ions, water and small molecules along the intercellular spaces between epithelial and FCs, driven by Na+-leak conductance; (ii) membrane transport of such solutes from the intercellular spaces into the fibre cytoplasm by specific carriers and transporters; (iii) gap-junctional coupling mediating solute flux between superficial and deeper fibres, Na+/K+-ATPase-driven efflux of waste products in the equator, and electrical coupling of fibres; and (iv) transcellular transfer via caveoli and coated vesicles for the uptake of macromolecules and cholesterol. There is evidence that the Na+-driven influx of solutes occurs via paracellular and membrane transport and the Na+/K+-ATPase-driven efflux of waste products via gap junctions. This micro-circulation is likely restricted to the superficial cortex and nearly absent beyond the zone of organelle loss, forming a solute exchange barrier in the lens.

    Original languageEnglish
    Pages (from-to)1265-1277
    Number of pages13
    JournalPhilosophical Transactions of the Royal Society B - Biological Sciences
    Volume366
    Issue number1568
    DOIs
    Publication statusPublished - 27 Apr 2011

    Keywords

    • vertebrate eye lens
    • solute flux
    • ultrastructure
    • gap junctions
    • MRI
    • dye loading
    • FIBER CELL-DIFFERENTIATION
    • ZONULAR PULVERULENT CATARACT
    • HUMAN EYE LENS
    • MEDIATED INTERCELLULAR COMMUNICATION
    • FIBROBLAST-GROWTH-FACTOR
    • AMINO-ACID-TRANSPORT
    • EPITHELIAL-CELL
    • RAT LENS
    • GAP-JUNCTIONS
    • MAMMALIAN LENS

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