The Journal of Membrane Biology

, Volume 162, Issue 1, pp 81–90

Nonselective Block by La3+ of Arabidopsis Ion Channels Involved in Signal Transduction


  • B.D.  Lewis
    • Department of Botany, University of Wisconsin-Madison, 430 Lincoln Drive, Madison, WI 53706, USA
  • E.P.  Spalding
    • Department of Botany, University of Wisconsin-Madison, 430 Lincoln Drive, Madison, WI 53706, USA

DOI: 10.1007/s002329900344

Cite this article as:
Lewis, B. & Spalding, E. J. Membrane Biol. (1998) 162: 81. doi:10.1007/s002329900344


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.

Key words: Lanthanum — La3+—Arabidopsis— Ion channels — Cold shock — Anion channel

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© 1998 Springer-Verlag New York Inc.