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Nonselective block by La3+ of Arabidopsis ion channels involved in signal transductionLanthanide ions such as La3+ are frequently used as blockers to test the involvement of calcium channels in plant and animal signal transduction pathways. For example, the large rise in cytoplasmic Ca2+ concentration triggered by cold shock in Arabidopsis seedlings is effectively blocked by 10 mM La3+ and we show here that the simultaneous large membrane depolarization is similarly blocked. However, a pharmacological tool is only as useful as it is selective and the specificity of La3+ for calcium channels was brought into question by our finding that it also blocked a blue light (BL)-induced depolarization that results from anion channel activation and believed not to involve calcium channels. This unexpected inhibitory effect of La3+ on the BL-induced depolarization is explained by our finding that 10 mM La3+ directly and completely blocked the BL-activated anion channel when applied to excised patches. We have investigated the ability of La3+ to block noncalcium channels in Arabidopsis. In addition to the BL-activated anion channel, 10 mM La3+ blocked a cation channel and a stretch-activated channel in patches of plasma membrane excised from hypocotyl cells. In root cells, 10 mM La3+ inhibited the activity of an outward-rectifying potassium channel at the whole cell and single-channel level by 47% and 58%, respectively. We conclude that La3+ is a nonspecific blocker of multiple ionic conductances in Arabidopsis and may disrupt signal transduction processes independently of any effect on Ca2+ channels.
Document ID
20040172753
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Lewis, B. D.
(University of Wisconsin-Madison 53706 United States)
Spalding, E. P.
Evans, M. L.
Date Acquired
August 22, 2013
Publication Date
March 1, 1998
Publication Information
Publication: The Journal of membrane biology
Volume: 162
Issue: 1
ISSN: 0022-2631
Subject Category
Life Sciences (General)
Distribution Limits
Public
Copyright
Other
Keywords
Non-NASA Center
NASA Discipline Plant Biology

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