Opposing Effects of Aluminum on Inward-Rectifier Potassium Currents in BeanRoot-Tip Protoplasts

Opposing Effects of Aluminum on Inward-Rectifier Potassium Currents in BeanRoot-Tip Protoplasts Inward currents in root cap protoplasts of the aluminum-tolerant cultivar, Dade, of Phaseolus vulgaris L. were investigated using the whole-cell patch-clamp technique. The properties of these currents were similar to those seen in inward rectifying K+ channels in other plant tissues. Replacing bath K+ with Na+ nearly abolished the observed currents. Higher bath K+ concentrations increased inward currents. AlCl3 in pH 4.7 bath solutions caused inward K+ currents to activate more rapidly and at more positive voltages when compared with AlCl3 free solutions. In 10 μM AlCl3 the activated inward K+ currents were significantly larger than in the AlCl3-free solution at all voltages except at the most negative voltage of −174 mV and the least negative of −74 mV. In contrast, in 80 μM Al3+, when hyperpolarizing voltages were most negative, the inward K+ currents were inhibited relative to the currents in 10 μM AlCl3. Enhancement of inward K+ currents by AlCl3 is consistent with Al3+ binding to the external surface of the root cap protoplast, decreasing the surface charge, thus causing the channels to sense a more negative membrane potential. Inhibition of inward K+ currents with higher AlCl3 concentrations and more negative voltages is consistent with Al3+ block of K+ channels. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Membrane Biology Springer Journals

Opposing Effects of Aluminum on Inward-Rectifier Potassium Currents in BeanRoot-Tip Protoplasts

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Publisher
Springer-Verlag
Copyright
Copyright © 2004 by Springer-Verlag
Subject
Life Sciences; Human Physiology; Biochemistry, general
ISSN
0022-2631
eISSN
1432-1424
D.O.I.
10.1007/s00232-004-0658-y
Publisher site
See Article on Publisher Site

Abstract

Inward currents in root cap protoplasts of the aluminum-tolerant cultivar, Dade, of Phaseolus vulgaris L. were investigated using the whole-cell patch-clamp technique. The properties of these currents were similar to those seen in inward rectifying K+ channels in other plant tissues. Replacing bath K+ with Na+ nearly abolished the observed currents. Higher bath K+ concentrations increased inward currents. AlCl3 in pH 4.7 bath solutions caused inward K+ currents to activate more rapidly and at more positive voltages when compared with AlCl3 free solutions. In 10 μM AlCl3 the activated inward K+ currents were significantly larger than in the AlCl3-free solution at all voltages except at the most negative voltage of −174 mV and the least negative of −74 mV. In contrast, in 80 μM Al3+, when hyperpolarizing voltages were most negative, the inward K+ currents were inhibited relative to the currents in 10 μM AlCl3. Enhancement of inward K+ currents by AlCl3 is consistent with Al3+ binding to the external surface of the root cap protoplast, decreasing the surface charge, thus causing the channels to sense a more negative membrane potential. Inhibition of inward K+ currents with higher AlCl3 concentrations and more negative voltages is consistent with Al3+ block of K+ channels.

Journal

The Journal of Membrane BiologySpringer Journals

Published: Jan 1, 2004

References

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