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 φm, resistance Rm, capacity Cm, while modifying the transport properties of the plasma membrane (PM).The average values of these quantities for 100 cells under standard conditions were φм = -171±0,4 mV Rм = 3.8±0,15 Om∙m2, Cm = 0,9 ± 0,05 μf∙ cm-2, respectively. Between Rm and φm has been established a linear dependence of Rm = 0,032-0,03φm with a coefficient correlation r = 0,67.The activity of K+ ions in the cell cytoplasm, measured using K+ -sensitive microelectrodes, was ak+ = 104 ± 6 mM. In the conducting state, in cells with | φм |> 170 mV, were observed K+- channels of inward rectification and in cells with | φм | +- channels of outward rectification. At 10 and 100-fold increase of the K+content in the medium, and modulation of the protein phase content in the PM, Cм change wasn’t observed. Consequently, the contribution of the protein phase in PM is insignificant for Cм.The exogenous effects of low concentrations of lipophilic modifiers of dimethyl sulfoxide, dicyclohexylcarbodiimide and the K+ channel blocker Co2 + caused a change of Cm by 20-30%, an increase in φm within 30 mV at a constant Rm, which indicated the relationship between electrogenic activity and lability of structural-polarization PM properties.