
%0 Journal Article
%A Babourina, Olga K. 
%A Knowles, Andrew E. 
%A Newman, Ian A. 
%T Chloride uptake by oat coleoptile parenchyma described by combined influx and efflux transport systems
%J Functional Plant Biology
%D 1999/01/29
%V 25
%N 8
%P 929-936
%K 
%R https://doi.org/10.1071/PP98100
%U https://www.publish.csiro.au/paper/PP98100 
%X Chloride fluxes for oat coleoptile parenchyma were measured using the MIFE system for non-invasive microelectrode ion flux measurement. The effects on chloride fluxes of membrane potential, external chloride concentration, pH, cation composition of the bathing solution, and the anion channel blocker anthracene-9-carboxylic acid were studied. From the experimental data we propose that the step-like appearance of the chloride uptake curve at concentrations higher than 1 mM is due to combined activity of influx and efflux systems. According to this hypothesis the uptake of chloride ions is made by a pH sensitive active transport system with Vmax = 4000 nmol m-2 s-1, Km = 7 mM &#91;Cl-&#93;. Chloride ions are released from the cell through channels with Gaussian type kinetics, the characteristics of which are dependent upon the external bathing solution: Vmax = &#8211;2300 nmol m-2 s-1 at 25 mM &#91;Cl-&#93; for CaCl2, and Vmax = &#8211;2000 nmol m-2 s-1 at 15 mM &#91;Cl-&#93; for KCl; with both curves having the same width of 17 mM &#91;Cl-&#93;. Key words: Cl- membrane transport, flux kinetics, Avena sativa L. 
