Net fluxes of H + and Ca 2+ around the elongation region of low-salt corn (Zea mays L.) roots were measured using the microelectrode ion flux estimation (MIFE) technique. At pH 5.2 two oscillatory components were found. Fast, 7-min oscillations in H + flux were superimposed on slow oscillations of about 1.5 h. Fast oscillations in Ca 2+ flux showed a strong dependence on the H + oscillations and were normally leading in phase by about 1 to 1.5 min. Both oscillatory components were strongly affected by external pH values. Preincubation for 20 h in buffered pH 4.0 solution suppressed the slow oscillatory component and caused huge H + influxes in the elongation region. The fast oscillations were 8 times larger in amplitude and were slightly lengthened. Preincubation at pH 6.0 did not suppress the rhythmic character of the ion fluxes but it shifted the average H + flux to greater efflux. The fast and slow oscillatory components of H + flux seem to relate to biophysical and biochemical mechanisms of intracellular pH homeostasis, respectively. The origin of the Ca 2+ flux oscillations is discussed in terms of the 'weak acid Donnan Manning' model of cell wall ion exchanges.

Item Type:	Refereed Article
Research Division:	Physical Sciences
Research Group:	Medical and biological physics
Research Field:	Biological physics
Objective Division:	Expanding Knowledge
Objective Group:	Expanding knowledge
Objective Field:	Expanding knowledge in the physical sciences
UTAS Author:	Shabala, SN (Professor Sergey Shabala)
UTAS Author:	Newman, IA (Dr Ian Newman)
UTAS Author:	Morris, J (Dr Morris)
ID Code:	10034
Year Published:	1997
Web of Science® Times Cited:	220
Deposited By:	Physics
Deposited On:	1997-08-01
Last Modified:	2005-06-07
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