Cytoplasmic Ca_ has No Effect on the Excitability of Chara Plasmalemma

元データ 日本植物生理学会


Internodal cells of Chara australis were subjected to two consecutive intracellular perfusions with a Ca,^<2+>_free EGTA medium which disintegrated the tonoplast within about 10 minutes and then with a Ca^<2+>_buffered medium. All perfusion media usually contained 1mM ATP. To stop the electrogenic pump, the internode was depleted of intracellular ATP. The excitability of the plasmalemma was not significantly influenced by intracellular free Ca^<2+> concentrations up to 10^<-4>M. To trigger action potentials, minimum current densities of 1 to 2μA cm^<-2> had to be applied at all tested Ca^<2+> concentrations. In the absence of cytoplasmic ATP, excitability was completely lost at all Ca^<2+> concentrations.


Tazawa Masashi Departlnent Of Biology Faculty Of Science Osaka University
Luhring Hinrich Department of Botany, Faculty of Science, University of Tokyo
Luhring Hinrich Department Of Botany Faculty Of Science University Of Tokyo:(present)botanisches Institute Der Unive