Bioelectric characteristics of Chara fragilis (Characeae) cells

Abstract

For the first time the data on the distribution of the potential (ϕm) and resistance (Rm) 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 ϕm and Rm. 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 ϕm were –183.0 ± 4.9 mV, Rm –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.