A short term NaCl exposure increases the Na+ conductance of outward-rectified cation currents in the pith cells of sweet pepper

M. Blom, S.A. Vogelzang

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    3 Citations (Scopus)

    Abstract

    The regulatory role of pith cells in the stem in Na recirculation in sweet pepper was investigated by evaluating the transport characteristics of the plasma membrane of this cell type and comparison with those of root cells. Ion conductivity and Na permeability of the plasma membranes of protoplasts of both cell types were studied with the patch-clamp technique in the whole-cell configuration, before and after addition of NaCl to the bath medium. Protoplasts of both pith and root cells showed outward rectifying currents with a reversal potential (Vr) near to the equilibrium potential of K (EK). Addition of NaCl to the bath medium caused a stronger shift of the reversal potential, Vr, in pith protoplasts than in root protoplasts, indicating that the outward rectified currents are permeable to Na , especially in the pith cells. After plant exposure to exogenous NaCl via the nutrient solution for 1 week, Vr in the root cells was closer to EK than in the control plants and hardly shifted upon addition of Na . This indicated that the net permeability of the OR channel complement in the plasma membrane to Na was lower following exposure to Na . Vr in the pith protoplasts, on the other hand, shifted significantly more than in the control plants, suggesting an increase of the permeability to Na . Moreover, the Na channel blocker amiloride blocked the currents in this cell type. It is concluded that pith cells have appropriate features of outward rectified currents to enable Na accumulation or release when NaCl is present in or removed from the nutrient medium. Probably, exogenous NaCl even induced expression and formation of Na -permeable channels in pith cells.
    Original languageEnglish
    Pages (from-to)47-55
    JournalBioelectrochemistry
    Volume60
    Issue number1-2
    DOIs
    Publication statusPublished - 2003

    Keywords

    • patch-clamp experiments
    • plasma-membrane
    • higher-plants
    • root-cells
    • ion channels
    • rye roots
    • tobacco protoplasts
    • xylem-parenchyma
    • sodium fluxes
    • barley roots

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