Seedling roots of cam were treated with different concentrations of mannitol-containing solution for 1 to 1.5 hr, and net fluxes of Ca2+ and H+ were measured in the elongation region. H+ fluxes were much more sensitive to osmotic pressure than were Ca2+ fluxes. Oscillations of 7-min period in H+ flux, normally observed in the control, were almost fully suppressed at high osmotic concentrations. Net H+ flux was shifted from average efflux of 25 ± 3 nmol m-2 sec-1 to average influx of 10 ± 5 nmol m-2 sec-1 after the incubation in 100 mM mannitol. The larger the osmotic concentration, the larger was the H+ influx. This flux caused the unbuffered solution of pH 4.85 to change to pH 5.3 after mannitol application, It appears that the osmoticum suppresses oscillatory H+ extrusion at the plasma membrane. Discrete Fourier Transforms of the H+ flux data showed that, apart from suppression of the 7-min oscillations in H+ flux, mannitol also promoted the appearance of faster 2-min oscillations. Ca2+ influx slightly increased after mannitol treatment. In addition the 7-min oscillatory component of Ca2+ flux remained apparent thereby showing independence of H+ flux.

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:	Shabala, SN (Professor Sergey Shabala)
Author:	Newman, IA (Dr Ian Newman)
ID Code:	13569
Year Published:	1998
Web of Science® Times Cited:	32
Deposited By:	Physics
Deposited On:	1998-08-01
Last Modified:	2011-08-08
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