For the first time the data on the distribution of the potential (ϕ_m) and resistance (R_m) in the plasma membrane and cell wall (R₀) of Chara fragilis cells were obtained using the Hogg method by the number of C. fragilis cells in standard conditions. The Hogg method allows simultaneous measurement of electrophysiological parameters, such as ϕ_m and R_m. The stationary values of the membrane potential and resistance varied in a rather wide range: –90...–300 mV and 1.0–32.6 Ohm·m², respectively. The average values of ϕ_m were –183.0 ± 4.9 mV, R_m –9.0 ± 1.2 Ohm·m². Using standard modifiers of membrane transport, the electrogenic activity of the cells was differentiated into two types: K⁺-channels and H⁺-membrane pumps. The activation ranges of the K⁺-inward rectifying channels and K⁺-outward rectifying channels are –130...–50 and –300...–162 mV, respectively. The cytosolic activity of K⁺-ions was 61.6 mmol/L. Since in our research, C. fragilis cells were studied for the first time, their electrogenic activity and ionic conductivity were tested using ammonium metavanadate (VO₃ˉ) – a proton pump inhibitor and tetraethylammonium (TEA⁺) – a universal blocker of K⁺-channels of plasma membranes. Chara fragilis cells can be recommended as a test object for establishing the mechanisms of changes in plasma membrane transport under exogenous stress factors influence.

Keywords: Chara fragilis, H⁺-pumps, K⁺-channels, membrane potential, membrane resistance, plasmalemma, TEA⁺-iodide, vanadate

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