Ion Transport in Liver Mitochondria

Rossi, C.S.; Gf, Azzone; Azzi, Angelo

doi:10.1007/978-3-662-25813-2_22

Cited by 11 publications

(18 citation statements)

References 12 publications

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“…Table 2 indicates that [14C]succinate accumulation, which occurs during the oxidation of TMPD plus ascorbate in the presence of antimycin, was strongly inhibited in the presence of 5 mM citrate, 5 mM malate or 5 mM a-oxoglutarate. A decrease in the mitochondrial binding of succinate by malate and by malonate has been reported very recently [9]. We have also found that malate has a strong inhibitory effect on mitochondria1 respiration supported by succinate plus rotenone as substrate.…”

Section: Accumulation and Oxidation Of Succinate In The Presence Of Osupporting

confidence: 63%

“…This is supported by the fact that the binding of succinate to the mitochondria is inhibited by a number of bi-or trivalent anionic substrates, but not by monovalent anions, and that succinate has an inhibitory effect on pyruvate uptake but not on citrate uptake at the same concentration. The competition between anions in mitochondria reported above may be compared to that between cations, such as Cat+ and Kf [5,9] 425.…”

Section: Discussionmentioning

confidence: 99%

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Control of Succinate Oxidation by Succinate‐Uptake by Rat‐Liver Mitochondria

Qquagliariello¹,

Palmieri²

1968

European Journal of Biochemistry

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The uptake of succinate by mitochondria and the rate of respiration in the presence of succinate plus rotenone have been analysed.1. I n conditions in which Vmax is the same, the apparent K , for succinate is lower when respiration is activated by ion uptake than it is in the active state. The highest value is obtained in the presence of 2,4dinitrophenol. 2. Succinate uptake is maximum during ion uptake, is lower in the active state and lowest in the uncoupled state.3. With increasing concentrations of uncoupler, a decrease in the intramitochondrial concentration of succinate is observed parallel to the decrease in respiration.4. The inhibition of respiration caused by gramicidin under certain conditions is accompanied by a decrease in the intramitochondrial concentration of succinate.5. Citrate and other substrate anions are shown to be competitive with succinate with respect to both the oxidation and the uptake of succinate.6. The inhibition of respiration by citrate is less pronounced in particles than in mitochondria. 7. It is concluded that the rate of respiration with succinate plus rotenone as substrate is controlled by succinate uptake.Phosphate and acetate are the best-known anions able to follow the movement of cations and accumulate within the mitochondria. Other anions which act in the same way have been reported by Azzi and Azzone [l], and Chance and Yoshioka [2]. Only recently has attention been drown to the behaviour of some mitochondrial substrates as anions [3-51. Important studies by Chappell and Haarhoff [6] showed that rat-liver mitochondria were permeable to some substrates, such as malate, succinate and citrate. Very recently in a note by Harris, van Dam, and Pressman [7] it was shown that the intramitochondrid concentration of succinate was decreased by high concentrations of uncouplers and increased in the presence of K+ and valinomycin. At the same time, similar results were also found by us and were the subject of a brief report 181. Furthermore, Rossi, Azzone, and Azzi 191 made the observation that succinate was bound to the mitochondria during Ca++ uptake and decreased the H+/Ca++ ratio from 2 to 1.I n this paper it is shown that succinate can accumulate within the mitochondria and that the rate of respiration supported by succinate plus rotenone is controlled by the accumulation of succinate, particularly when low concentrations of substrate are used.Non-Standard Abbreviations. DNP, 2,4-dinitrophenol; TMPD, tetramethyl-p-phenylenediamine.

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Section: Accumulation and Oxidation Of Succinate In The Presence Of Osupporting

confidence: 63%

Section: Discussionmentioning

confidence: 99%

Control of Succinate Oxidation by Succinate‐Uptake by Rat‐Liver Mitochondria

Qquagliariello¹,

Palmieri²

1968

European Journal of Biochemistry

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“…This is to be expected from the close similarity in binding properties of these two cations and is demonstrably so both from the identical concentration ofbinding sites for each (Reynafarje &Lehninger, 1969;Rossi et al, 1967;Scarpa & Azzi, 1968;and Fig. 9 of the present paper) and by the inhibition of low-affinity Ca2+ binding by La3+ (Lehninger & 6 K. C. REEDt AND F. L. BYGRAVE ).…”

Section: External Bindingmentioning

confidence: 53%

The inhibition of mitochondrial calcium transport by lanthanides and Ruthenium Red

Reed

Bygrave

1974

Biochemical Journal

348

160

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An EGTA (ethanedioxybis(ethylamine)tetra-acetic acid)-quench technique was developed for measuring initial rates of (45)Ca(2+) transport by rat liver mitochondria. This method was used in conjunction with studies of Ca(2+)-stimulated respiration to examine the mechanisms of inhibition of Ca(2+) transport by the lanthanides and Ruthenium Red. Ruthenium Red inhibits Ca(2+) transport non-competitively with K(i) 3x10(-8)m; there are 0.08nmol of carrier-specific binding sites/mg of protein. The inhibition by La(3+) is competitive (K(i)=2x10(-8)m); the concentration of lanthanide-sensitive sites is less than 0.001nmol/mg of protein. A further difference between their modes of action is that lanthanide inhibition diminishes with time whereas that by Ruthenium Red does not. Binding studies showed that both classes of inhibitor bind to a relatively large number of external sites (probably identical with the ;low-affinity' Ca(2+)-binding sites). La(3+) competes with Ruthenium Red for most of these sites, but a small fraction of the bound Ruthenium Red (less than 2nmol/mg of protein) is not displaced by La(3+). The results are discussed briefly in relation to possible models for a Ca(2+) carrier.

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“…The overall stoicheiometry relating respiration to proton translocation, and hence to the rate of proton cycling, is such that the passage of two reducing equivalents from succinate to oxygen is associated with the initial extrusion of four H+ (Mitchell & Moyle, 1967b), and that through the intermediacy of ionophore A23187, this is coupled to the cycling of 2 Ca2+ across the membrane. It should be noted that complete charge neutralization is required for sustained transport under steady-state conditions such as those described in this paper, and that this should not be confused with initial-uptake studies where the parallel movement of unspecified ions leads to ratios of H+ extruded to Ca2+ accumulated of close to 1, instead of the 2 required for electroneutrality (Rossi & Azzone, 1965;Rossi et al, 1967;Gear et al, 1967;Lehninger et al, 1967;Gear & Lehninger, 1968;Scarpa & Azzone, 1968;.…”

Section: Nativementioning

confidence: 84%

The calcium conductance of the inner membrane of rat liver mitochondria and the determination of the calcium electrochemical gradient

Heaton¹,

Nicholls²

1976

Biochemical Journal

136

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1. A method is described for establishing steady-state conditions of calcium transport across the inner membrane of rat liver mitochondria and for determining the current of Ca2+ flowing across the membrane, together with the Ca2+ electrochemical gradient across the native Ca2+ carrier. These parameters were used to quantify the apparent Ca2+ conductance of the native carrier. 2. At 23 degrees C and pH7.0, the apparent Ca2+ conductance of the carrier is close to 1 nmol of Ca2+-min-1-mg of protein-1 mV-1. Proton extrusion by the respiratory chain, rather than the Ca2+ carrier itself, may often be rate-limiting in studies of initial rates of Ca2+ uptake. 3. Under parallel conditions, the endogenous H+ conductance of the membrane is 0.3 nmol of H+-min-1-mg of protein-1-mV-1. 4. Ruthenium Red and La3+ both strongly inhibit the Ca2+ conductance of the carrier, but are without effect on the H+ conductance of the membrane. 5. The apparent Ca2+ conductance of the carrier shows a sigmoidal dependence on the activity of Ca2+ in the medium. At 23 degrees C and pH7.2, half-maximum conductance is obtained at a Ca2+ activity of 4.7 muM. 6. The apparent Ca2+ conductance and the H+ conductance of the inner membrane increase fourfold from 23 degrees to 38 degrees C. The apparent Arrhenius activation energy for Ca2+ transport is 69kJ/mol. The H+ electrochemical gradient maintained in the absence of Ca2+ transport does not vary significantly with temperature. 7. The apparent Ca2+ conductance increases fivefold on increasing the pH of the medium from 6.8 to 8.0. The H+ conductance of the membrane does not vary significantly with pH over this range. 8. Mg2+ has no effect on the apparent Ca2+ conductance when added at concentration up to 1 mM. 9. Results are compared with classical methods of studying Ca2+ transport across the mitochondrial inner membrane.

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Ion Transport in Liver Mitochondria

Cited by 11 publications

References 12 publications

Control of Succinate Oxidation by Succinate‐Uptake by Rat‐Liver Mitochondria

Control of Succinate Oxidation by Succinate‐Uptake by Rat‐Liver Mitochondria

The inhibition of mitochondrial calcium transport by lanthanides and Ruthenium Red

The calcium conductance of the inner membrane of rat liver mitochondria and the determination of the calcium electrochemical gradient

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