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 V(max) = 4000 nmol m-2 s-, K(m) = 7 mM [Cl-]. Chloride ions are released from the cell through channels with Gaussian type kinetics, the characteristics of which are dependent upon the external bathing solution: V(max) = -2300 nmol m-2 s-1 at 25 mM [Cl-] for CaCl2, and V(max) = -2000 nmol m-2 s-1 at 15 mM [Cl-] for KCl; with both curves having the same width of 17 mM [Cl-].

Item Type:	Refereed Article
Research Division:	Physical Sciences
Research Group:	Other Physical Sciences
Research Field:	Biological Physics
Objective Division:	Expanding Knowledge
Objective Group:	Expanding Knowledge
Objective Field:	Expanding Knowledge in the Physical Sciences
Author:	Babourina, OK (Dr Olga Babourina)
Author:	Knowles, AE (Mr Andrew Knowles)
Author:	Newman, IA (Dr Ian Newman)
ID Code:	14499
Year Published:	1998
Web of Science® Times Cited:	7
Deposited By:	Physics
Deposited On:	1998-08-01
Last Modified:	2011-08-09
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