Functional activity and structural lability of plasma membrane in <i>Nitellopsis obtusa </i>cells
Using the method of impedance spectroscopy, we studied the change regularities in the three electrical characteristics of Nitellopsis obtuse cells: potential φ<sub>m</sub>, resistance R<sub>m</sub>, capacity C<sub>m</sub>, while modifying the transport properties of the plasma membrane (PM).The average values of these quantities for 100 cells under standard conditions were φ<sub>м</sub> = -171±0,4 mV R<sub>м</sub> = 3.8±0,15 Om∙m<sup>2</sup>, C<sub>m</sub> = 0,9 ± 0,05 μf∙ cm<sup>-2</sup>, respectively. Between R<sub>m</sub> and φ<sub>m</sub> has been established a linear dependence of R<sub>m</sub> = 0,032-0,03φ<sub>m </sub>with a coefficient correlation r = 0,67.The activity of K<sup>+</sup> ions in the cell cytoplasm, measured using K<sup>+</sup> -sensitive microelectrodes, was a<sub>k</sub><sup>+</sup> = 104 ± 6 mM. In the conducting state, in cells with | φ<sub>м</sub> |> 170 mV, were observed K<sup>+</sup>- channels of inward rectification and in cells with | φ<sub>м</sub> | <170 mV-K<sup>+</sup>- channels of outward rectification. At 10 and 100-fold increase of the K<sup>+</sup>content in the medium, and modulation of the protein phase content in the PM, C<sub>м</sub> change wasn’t observed. Consequently, the contribution of the protein phase in PM is insignificant for C<sub>м</sub><sub>.</sub>The exogenous effects of low concentrations of lipophilic modifiers of dimethyl sulfoxide, dicyclohexylcarbodiimide and the K<sup>+</sup> channel blocker Co<sup>2 + </sup>caused a change of C<sub>m</sub> by 20-30%, an increase in φ<sub>m</sub> within 30 mV at a constant R<sub>m</sub>, which indicated the relationship between electrogenic activity and lability of structural-polarization PM properties.