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

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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä

Date

2010

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en

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1-12

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PLOS ONE, Volume 5, issue 9

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.

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Vinberg , F & Koskelainen , A 2010 , ' Calcium Sets the Physiological Value of the Dominant Time Constant of Saturated Mouse Rod Photo response Recovery ' , PloS one , vol. 5 , no. 9 , e13025 , pp. 1-12 . https://doi.org/10.1371/journal.pone.0013025