Chloride Accumulation by Mung Bean Root Tips: A Low Affinity Active Transport System at the Plasmalemma 1
AUTOR(ES)
Gerson, Donald F.
RESUMO
Net uptake of Cl− into root tips of mung bean (Phaseolus aureus) increases steadily with increasing external concentrations from 1 to 60 mm. Membrane potentials were measured to determine the equilibrium concentration of Cl− in the tissue which could be due to diffusion. This concentration was readily exceeded in both the relatively nonvacuolate tips (0 to 1 mm) and the vacuolate, mature upper sectons (1 to 11 mm) of the roots. The activity coefficient of both cytoplasmic and vacuolar Cl−, measured with Cl− sensitive microelectrodes, was approximately the same as that of a pure KCl solution of the same concentration. It is concluded that the “second mechanism” of ion uptake involves a large increase in the rate of active transport at the plasmalemma as the external concentration is increased above 1 mm.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=366199Documentos Relacionados
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