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K + and Cl − Conductance of Arabidopsis thaliana Plasma Membrane at Depolarized Voltages
Author(s) -
Cerana Raffaella,
Colombo Roberta
Publication year - 1992
Publication title -
botanica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.871
H-Index - 87
eISSN - 1438-8677
pISSN - 0932-8629
DOI - 10.1111/j.1438-8677.1992.tb00298.x
Subject(s) - conductance , membrane , ion , chemistry , membrane potential , efflux , ion transporter , patch clamp , analytical chemistry (journal) , permeability (electromagnetism) , potassium , alkali metal , biophysics , ion channel , inorganic chemistry , chromatography , biochemistry , physics , biology , receptor , organic chemistry , condensed matter physics
The ion currents, activated by depolarizations, across the plasma membrane of Arabidopsis thaliana cultured cells were studied by means of the patch‐clamp technique in the whole‐cell configuration. The electrical conductance of the membrane could be shifted from a cation to an anion conducting state by changes in the [K + ]: [Cl − ] ratio in the external medium. For ratios between 1:1 and 1:5 the currents were due to K + efflux and for a ratio of 1:10 to Cl − influx. In the cation conducting state the permeability ratio of K + over NH + 4 and the alkali metal ions was: K + ≅ NH>Na + ≅ Li + >Cs + . In the anion conducting state the permeability of NO − 3 was the same as that of Cl − . These channels were activated by depolarizations in the range of physiological potentials (‐70/‐80mV) and, either by mediating the efflux of cations or the influx of anions, they could function to re‐hyperpolarize the membrane potential after depolarizations due to the influx of cations or of solutes cotransported with protons and/or to the inhibition of electrogenic pumps.