Calcium Sets the Physiological Value of the Dominant Time Constant of Saturated Mouse Rod Photo response Recovery

Frans Vinberg, Ari Koskelainen

    Research output: Contribution to journalArticleScientificpeer-review

    11 Citations (Scopus)
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    Abstract

    Background

    The rate-limiting step that determines the dominant time constant (τD) of mammalian rod photoresponse recovery is the deactivation of the active phosphodiesterase (PDE6). Physiologically relevant Ca2+-dependent mechanisms that would affect the PDE inactivation have not been identified. However, recently it has been shown that τD is modulated by background light in mouse rods.

    Methodology/Principal Findings

    We used ex vivo ERG technique to record pharmacologically isolated photoreceptor responses (fast PIII component). We show a novel static effect of calcium on mouse rod phototransduction: Ca2+ shortens the dominant time constant (τD) of saturated photoresponse recovery, i.e., when extracellular free Ca2+ is decreased from 1 mM to ∼25 nM, the τD is reversibly increased ∼1.5–2-fold.

    Conclusions

    We conclude that the increase in τD during low Ca2+ treatment is not due to increased [cGMP], increased [Na+] or decreased [ATP] in rod outer segment (ROS). Also it cannot be due to protein translocation mechanisms. We suggest that a Ca2+-dependent mechanism controls the life time of active PDE.
    Original languageEnglish
    Article numbere13025
    Pages (from-to)1-12
    JournalPloS one
    Volume5
    Issue number9
    DOIs
    Publication statusPublished - 2010
    MoE publication typeA1 Journal article-refereed

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