Patch-clamp study on ion channels in the tonoplast of nitellopsis obtusa

Maki Katsuhara, Tetsuro Mimura, Masashi Tazawa

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)


Cytoplasmic drops covered with the tonoplast were prepared from internodal cells of Nitellopsis grown in fresh water. Applying the patch-clamp technique and the microinjection technique to such drops, we characterized the ion channels in the tonoplast. Both in cell-free patches and in the cytoplasmic-drop-attached patches, the tonoplast K+ channel was identified. The permeability ratio between Na+ and K+ was calculated to be 0.2. This channel would provide a molecular basis for the Na+/K+ exchange at the tonoplast. In cell-free patches, the K+channel was not activated by Ca2+. However, in the case of attached patches, microinjection of Ca2+ into a drop activated the K+ channel with a lag of a few seconds, suggesting that some cytoplasmic factor(s) may mediate the activation of the K+ channel by Ca2+. The conductance of this channel was not changed by cytoplasmic Ca2+, but the probability of opening increased markedly. In addition to the K+ channel, a second type of channel was also identified in cell-free patches. This channel may be the Cl- channel.

Original languageEnglish
Pages (from-to)179-184
Number of pages6
JournalPlant and Cell Physiology
Issue number2
Publication statusPublished - Mar 1991
Externally publishedYes


  • Calcium regulation
  • Nitellopsis obtusa
  • Patch clamp
  • Salt stress
  • Tonoplast

ASJC Scopus subject areas

  • Physiology
  • Plant Science
  • Cell Biology


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