Proton electrochemical potential in steady state rat liver mitochondria

Azzone, Giovanni; Bragadin, Marcantonio; Pozzan, Tullio; Antone, Paolo Dell'

doi:10.1016/0005-2728(77)90012-3

Cited by 71 publications

(22 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In this system similar values of Atp were obtained from the use of 86Rb (+ valinomycin) and 3H-TPMP § 1 In E. coli cells similar values were obtained by microelectrodes and TPP § [5]. However, in mitochondria and other systems it was noted that the values calculated from different cations are not identical [1,10,27,33]. In several bacterial species similar discrepancies were also noted [2,11,34].…”

Section: Introductionmentioning

confidence: 66%

Membrane potential and surface potential in mitochondria: Uptake and binding of lipophilic cations

1984

View full text Add to dashboard Cite

The uptake and binding of the lipophilic cations ethidium+, tetraphenylphosphonium+ (TPP+), triphenylmethylphosphonium+ (TPMP+), and tetraphenylarsonium+ (TPA+) in rat liver mitochondria and submitochondrial particles were investigated. The effects of membrane potential, surface potentials and cation concentration on the uptake and binding were elucidated. The accumulation of these cations by mitochondria is described by an uptake and binding to the matrix face of the inner membrane in addition to the binding to the cytosolic face of the inner membrane. The apparent partition coefficients between the external medium and the cytosolic surface of the inner membrane (K'o) and the internal matrix volume and matrix face of the inner membrane (K'i) were determined and were utilized to estimate the membrane potential delta psi from the cation accumulation factor Rc according to the relation delta psi = RT/ZF ln [(RcVo - K'o)/(Vi + K'i)] where Vo and Vi are the volume of the external medium and the mitochondrial matrix, respectively, and Rc is the ratio of the cation content of the mitochondria and the medium. The values of delta psi estimated from this equation are in remarkably good agreement with those estimated from the distribution of 86Rb in the presence of valinomycin. The results are discussed in relation to studies in which the membrane potential in mitochondria and bacterial cells was estimated from the distribution of lipophilic cations.

show abstract

Section: Introductionmentioning

confidence: 66%

Membrane potential and surface potential in mitochondria: Uptake and binding of lipophilic cations

1984

View full text Add to dashboard Cite

show abstract

“…TPMP + has been shown to be a freely permeant cation across cell membranes (Skulachev, 1971), and its equilibrium distribution has been demonstrated to be dependent on the resting ~ in a variety of systems (Bakeeva et al, 1970 ;Grinius et al, 1970;Hirata, Altendorf & Harold, 1973;Lombardi et al, 1974;Altendorf, Hirata & Harold, 1975;Heinz, Geck & Peitreyk, 1975;Schuldiner & Kaback, 1975;Azzone et al, 1976;Miller & Budd, 1976;Grollman et al, 1977;Azzone et al, 1978 ;Deutsch & Kfila, 1978 ;Korchak & Weismann, I978;Deutsch et al, 1979b;Lichtshtein et al, 1979a;Ramos et al, 1979;Deutsch et al, 1979a). Therefore, by estimating the transmembrane concentration gradient of TPMP +, can be calculated simply from the Nernst relation:…”

Section: Theorymentioning

confidence: 98%

Measurement of membrane potentials (ψ) of erythrocytes and white adipocytes by the accumulation of triphenylmethylphosphonium cation

et al. 1980

View full text Add to dashboard Cite

The accumulation of the lipophilic cation, triphenylmethylphosphonium, has been employed to determine the resting membrane potential in human erythrocytes, turkey erythrocytes, and rat white adipocytes. The triphenylmethylphosphonium cation equilibrates rapidly in human erythrocytes in the presence of low concentrations of the hydrophobic anion, tetraphenylborate. Tetraphenylborate does not accelerate the uptake of triphenylmethylphosphonium ion by adipocytes. The cell associated vs. extracellular distribution of the triphenylmethylphosphonium ion is proportional to changes in membrane potential. The distribution of this ion reflects the membrane potential determining concentration of the ion with dominant permeability in a "Nernst" fashion. The resting membrane potentials for the human erythrocyte, turkey erythrocyte, and rat white adipocyte were found to be -8.4 +/- 1.3, -16.8 +/- 1.1, and -58.3 +/- 5.0 mV, respectively, values which compare favorably with values obtained by other methods. In addition, changes in membrane potential can be assessed by following triphenylmethylphosphonium uptake without determining the intracellular water space. The method has been successfully applied to a study of hormonally induced changes in membrane potential of rat white adipocytes.

show abstract

“…Membrane potentials have been evaluated by measuring the distribution of radioactively labeled permeant lipophilic ions. This approach was first introduced by Skulachev and coworkers (6)(7)(8) and has been applied to a variety of biological systems (6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20). These experiments were carried out at room temperature as described (19,20 Measurements of Energy Parameters.…”

mentioning

confidence: 99%

Cellular energy metabolism, trans-plasma and trans-mitochondrial membrane potentials, and pH gradients in mouse neuroblastoma

Deutsch¹,

Erecińska²,

Werrlein³

et al. 1979

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

(mitochondria-to-cytoplasm gradients) to be made and suggests that the trans-mitochondrial membrane protonmotive force in the intact cell cannot be greater than -143 mV.Assessment of the electrical potential and ion gradients across subcellular compartments in the intact cell is an important goal that has not been pursued directly; isolation of subcellular compartments and subsequent in vitro studies have been the predominant approach, although possible redistribution of ionic species during isolation raises doubts with respect to the validity of this procedure. In this communication, we present a quantitative approach to the evaluation of the transmembrane electrical potential and pH gradients across a subcellular compartment in an intact cell. The requisite information for such evaluations includes: (i) relative volumes of the subcellular compartment and the cell; (ii) a known (measured) value of trans-plasma membrane electrical potential and pH gradient; and (iii) measured total concentrations of ions and weak acids/bases that distribute passively in the cell and in the compartment. These distributions give estimates of the cytosol-to-extracellular space gradient plus the compartment-tocytosol gradients.We have used this approach to evaluate the total trans-mitochondrial protonmotive force (the electrical plus pH gradients across the mitochondrial membrane) in mouse neuroblastoma Hanks' medium (3) containing 10 mM Hepes (pH 7.4) and 0.05% bovine serum albumin and finally resuspended in the same medium at 25-30 mg wet weight/ml. These suspensions were passed through a wire mesh (20-to 40-,m pore size diameter) in order to produce suspension homogeneity. Suspensions treated in this manner showed no clumps (no more than three cells grouped together) under a microscope. The dry weights of the cell suspension and the medium were determined for each preparation.For microelectrode measurements, cells were grown in Nunclon plastic petri dishes for 2-3 days as described above. Measurements of membrane potential were made while most of the cells were still in the exponential growth phase.Microelectrode Measurements. The medium in the petri dish was poured off and replaced by Hanks' medium containing 10 mM Hepes (pH 7.4) and 0.05% bovine serum albumin. The dish was placed on an inverted high-power microscope with a warmed stage (20-25°C). The electrode assembly was advanced by a remote stepping-motor hydraulic system. The microscope and the electrode carrier were contained within an electrically shielded cage and a humidified chamber. Lighting was via a fiber optic, heat-filtered high intensity source (Leitz, West Germany). After the lid of the petri dish was removed, the electrode was inserted under direct vision into randomly selected cells adhering to the floor of the dish. Only those Abbreviation: TPMP, triphenylmethyl phosphonium ion. Thomas (5). Some electrodes were ground to a chisel point on an optically flat grinding machine to allow easier penetration of the cell membrane.Isotope Distribution Measurement...

show abstract

Proton electrochemical potential in steady state rat liver mitochondria

Cited by 71 publications

References 19 publications

Membrane potential and surface potential in mitochondria: Uptake and binding of lipophilic cations

Membrane potential and surface potential in mitochondria: Uptake and binding of lipophilic cations

Measurement of membrane potentials (ψ) of erythrocytes and white adipocytes by the accumulation of triphenylmethylphosphonium cation

Cellular energy metabolism, trans-plasma and trans-mitochondrial membrane potentials, and pH gradients in mouse neuroblastoma

Contact Info

Product

Resources

About