Nonselective block by La3+ of Arabidopsis ion channels involved in signal transduction

Lanthanide 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 La...

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Bibliographic Details
Published in:The Journal of membrane biology 1998-03, Vol.162 (1), p.81-90
Main Authors: Lewis, B.D, Spalding, E.P
Format: Article
Language:English
Subjects:
Arabidopsis - drug effects
ARABIDOPSIS THALIANA
CALCIO
CALCIUM
Calcium - metabolism
CATION
CATIONES
CATIONS
Cell Membrane - physiology
CHOC
COLD SHOCK
Cold Temperature
ELECTROPHYSIOLOGY
ELEMENTOS DE TIERRAS RARAS
ESTRES TERMICO
HIPOCOTILOS
HYPOCOTYLE
HYPOCOTYLS
ION
Ion Channels - drug effects
Ion Channels - physiology
ION TRANSPORT
IONES
IONS
LANTHANUM
Lanthanum - pharmacology
Life Sciences (General)
Light
METAL DES TERRES RARES
RARE EARTH ELEMENTS
SHOCK
Signal Transduction
Space life sciences
STRESS THERMIQUE
THERMAL STRESS
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Summary:Lanthanide 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.
ISSN:0022-2631
1432-1424
DOI:10.1007/s002329900344