Patch-Clamp Study on Ion Channels in the Tonoplast of Nitellopsis obtusa

元データ 日本植物生理学会


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 Ca^<2+>. However, in the case of attached patches, microinjection of Ca^<2+> 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 Ca^<2+>. The conductance of this channel was not changed by cytoplasmic Ca^<2+> , 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.


Mimura T Hitotsubashi Univ. Tokyo Jpn
Mimura T Himeji Inst. Technology Hyogo Jpn
Mimura Tetsuro Department Of Biological Science Faculty Of Science Nara-women's University
KATSUHARA Maki Research Institute for Bioresources, Okayama University
Katsuhara M Research Institute For Bioresources Okayama University
Katsuhara Maki Department Of Insect Physiology And Behavior National Institute Of Sericultural And Entomological Sc
Tazawa M Fukui Univ. Technol. Fukui Jpn
Tazawa Masashi Department Of Applied Physics And Chemistry Fukui University Of Technology
Tazawa Masashi Departlnent Of Biology Faculty Of Science Osaka University