Membrane potential fluctuations in Chara australis: a characteristic signature of high external sodium.
We have studied fluctuations in membrane PD in Chara australis at frequencies between 1 and 500 mHz, by classical noise analysis and by inspection of the PD time-course. The former shows (1) a quasi-Lorentzian (1/f (2)) rise of noise power as frequency falls, and (2) a marked increase in noise power when the cell is exposed to high salinity (Chara australis is a salt-sensitive species). The latter shows that, as well as initiating depolarization, exposure to 50 mM Na as either chloride or sulfate usually initiates a continuous but random series of small depolarizations which gives rise to the increase in noise and whose mechanism is discussed.
Al Khazaaly
Sabah
S
Plant Membrane Biophysics Group, School of Physics, University of NSW, Sydney, NSW, 2052, Australia.
Alan Walker
N
N
Beilby
Mary Jane
MJ
Shepherd
Virginia A
VA
D044784:Chara / Q000166:cytology* / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D008564:Membrane Potentials / Q000187:drug effects*; D009994:Osmolar Concentration; D009997:Osmotic Pressure; D054712:Salinity; D012964:Sodium / Q000494:pharmacology*; D013997:Time Factors
D012964:Sodium