The Journal of Membrane Biology

, Volume 155 , Issue 1 , pp 35 –45

Hyperpolarization-activated Ca2+-permeable Channels in the Plasma Membrane of Tomato Cells

  • A.  Gelli
  • E.  Blumwald

DOI: 10.1007/s002329900156

Cite this article as:
Gelli, A. & Blumwald, E. J. Membrane Biol. (1997) 155: 35. doi:10.1007/s002329900156

Abstract.

The hyperpolarization of the electrical plasma membrane potential difference has been identified as an early response of plant cells to various signals including fungal elicitors. The hyperpolarization-activated influx of Ca2+ into tomato cells was examined by the application of conventional patch clamp techniques. In both whole cell and single-channel recordings, clamped membrane voltages more negative than −120 mV resulted in time- and voltage-dependent current activation. Single-channel currents saturated with increasing activities of Ca2+ and Ba2+ from 3 to 26 mm and the single channel conductance increased from 4 pS to 11 pS in the presence of 20 mm Ca2+ or Ba2+, respectively. These channels were 20–25 and 10–13 times more permeable to Ca2+ than to K+ and to Cl, respectively. Channel currents were strongly inhibited by 10 μm lanthanum and 50% inhibited by 100 μm nifedipine. This evidence suggests that hyperpolarization-activated Ca2+-permeable channels provide a mechanism for the influx of Ca2+ into tomato cells.

Key words: Tomato protoplasts — Patch clamp — Calcium channels — Hyperpolarized electrical membrane potential differences — Signal transduction 

Copyright information

© 1997 Springer-Verlag New York Inc.

Authors and Affiliations

  • A.  Gelli
    • 1
  • E.  Blumwald
    • 1
  1. 1.Department of Botany, University of Toronto, 25 Willcocks Street, Toronto, Ontario CANADA M5S 3B2CA

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