Estimation of the electric plasma membrane potential difference in yeast with fluorescent dyes: comparative study of methods

The characteristics of the plasma-membrane potential of procyclic and bloodstream forms of Trypanosoma brucei brucei (cultured cells) were investigated using the fluorescent anionic probe bisoxonol. Observation of a stable and representative plasma-membrane potential in the resting state required careful washing, centrifugation and maintenance of the cells at room temperature before measurement. Bloodstream forms were more prone to depolarization during washing at 4 °C than procyclic cells. The higher fluorescence observed in the presence of long slender cells than in the presence of procyclic cells shows that the plasma-membrane potential is more negative in the insect form. Healthy dilute cells can sustain their plasma-membrane potential for hours in the presence of external glucose. The presence of a high K+ concentration in the medium did not promote by itself the depolarization of either type of cell. Study of bisoxonol fluorescence as a function of time allowed us to follow the kinetics of the action of metabolic inhibitors in the presence of various ions. o-Vanadate (1 mM) was found to depolarize bloodstream-form cells rapidly but only in a phosphate-free NaCl buffer. Omeprazole and strophanthidin also specifically depolarized bloodstream-form trypanosomes. However, NN´-dicyclohexylcarbodi-imide depolarized both types of cell, but more rapidly for bloodstream-form cells. Bloodstream-form trypanosomes appear to use mainly a vanadate-sensitive Na+ pump to maintain their Na+-diffusion gradient. However, most of the ATPase inhibitors tested had little or no effect on the plasma-membrane potential of procyclics suggesting that this form of trypanosome may rely on several regulation mechanisms.

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Investigation of the mechanism of hepatotoxicity of N-methylformamide in mice: Effects on calcium sequestration in hepatic microsomes and mitochondria and on hepatic plasma membrane potential

Biochemical and Biophysical Research Communications ◽

10.1016/0006-291x(84)90597-7 ◽

1984 ◽

Vol 125 (2) ◽

pp. 712-718 ◽

Cited By ~ 4

Author(s):

Helen Whitby ◽

Suresh B. Chahwala ◽

Andreas Gescher

Keyword(s):

Plasma Membrane ◽

Membrane Potential ◽

Plasma Membrane Potential ◽

Calcium Sequestration ◽

Hepatic Microsomes

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Sodium Cotransport Systems and the Membrane Potential Difference

Annals of the New York Academy of Sciences ◽

10.1111/j.1749-6632.1985.tb14844.x ◽

1985 ◽

Vol 456 (1 Membrane Tran) ◽

pp. 51-62 ◽

Cited By ~ 15

Author(s):

A. ALAN EDDY

Keyword(s):

Membrane Potential ◽

Potential Difference ◽

Sodium Cotransport ◽

Membrane Potential Difference ◽

Cotransport Systems

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Effects of Ultraviolet Radiation on the Plasma Membranes of Chara corallina. I The Hyperpolarized State

Functional Plant Biology ◽

10.1071/pp9760677 ◽

1976 ◽

Vol 3 (5) ◽

pp. 677

Author(s):

C.J Doughty ◽

A.B Hope

Keyword(s):

Membrane Potential ◽

Ultraviolet Radiation ◽

Ultraviolet Irradiation ◽

Plasma Membranes ◽

Membrane Conductance ◽

Chara Corallina ◽

Potential Difference ◽

Electrogenic Pump ◽

Chloride Permeability ◽

Membrane Potential Difference

Effects of 254 nm ultraviolet irradiation on the plasmalemma potential difference and conductance in C, corallina have been further analysed. Following an increase in passive chloride permeability, revealed from previous studies, and which is manifested as a depolarization of membrane potential difference and an increase in membrane conductance, a secondary depolarization was prominent at pH 7 and is attributed to u.v.-induced inhibition of an electrogenic pump. The secondary depolarization was usually accompanied by a decrease in membrane conductance. For doses of u.v. of 1400 J m-2, these effects were almost reversible within about 1 h

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