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Mechanisms of Sodium and Rubidium Uptake by Excised Barley Roots
Author(s) -
NEUMANNGANMORE RUTH,
WAISEL Y.
Publication year - 1972
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1972.tb03634.x
Subject(s) - rubidium , sodium , chemistry , diffusion , metabolism , absorption (acoustics) , biophysics , biochemistry , mechanism (biology) , metabolic pathway , potassium , biology , materials science , organic chemistry , physics , philosophy , epistemology , composite material , thermodynamics
Accumulation of sodium and rubidium by excised barley roots was investigated. The concentration isotherm yielded one absorption shoulder. Nevertheless, it is suggested that two mechanisms take part in the uptake of sodium and rubidium: One non‐metabolic mechanism with an apparent participation at low external salt concentrations (< 1 m M ) and at high concentrations (> 20 m M ). Such a mechanism is almost unaffected by low temperature conditions and by metabolic inhibitors. Rubidium possesses a high affinity toward this non‐metabolic system. The second mechanism is sensitive to metabolic inhibitors and to low temperature conditions. It dominates at intermediate external concentrations (1–20 m M ). Sodium possesses high affinity towards this mechanism. The two mechanisms operate in a parallel manner beyond a diffusion barrier (= plasmamembrane) surrounding the cells. It is assumed that both the metabolic and the non‐metabolic mechanisms operate in the entire concentration spectrum, but their relative contribution to the total uptake varies at different ranges.