A membrane potential‐modulated pathway for Ca<sup>2+</sup> efflux in rat liver mitochondria

Bernardi, Paolo; Azzone, Giovanni

doi:10.1016/0014-5793(82)80476-6

Cited by 46 publications

(22 citation statements)

References 18 publications

(5 reference statements)

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“…Another is that of an activation of the A $-controlled pathway consequent to the Pi-induced shift from the chemical to the electrical component of AbH. The former interpretation is supported by the very low concentration of Pi (maximal effect 0.2-0.3 mM) required to activate the Ca" efflux [28]. The latter interpretation is on the other hand supported by the experiment of Fig.…”

Section: Activirtion Of the Ejflux Puthwuy By Hypotonic Swelling And supporting

confidence: 73%

“…The experiment of Fig. 2 thus indicates that the biphasic relationship between steady state pCa, and A $ is independent of the agents or conditions used to depress A $ , the same pattern being obtained when A $ is depressed by uncouplers [28], respiratory inhibitors or an inward K + current.…”

Section: Resultsmentioning

confidence: 82%

“…The increase of steady-state pCa, following membrane depolarization has been interpreted [28] as due to a decreased activity of a membrane-potential-modulated pathway for Ca2 + efflux. It is generally believed that the independent pathway for CaZ+ release at high A $ is reflected by the ruthenium-redinsensitive Ca2+ efflux [23].…”

Section: Activirtion Of the Ejflux Puthwuy By Hypotonic Swelling And mentioning

confidence: 99%

“…The observations of the present investigation differ so radically from the others that it is legitimate to ask whether a biphasic relationship between pCa, and A $ may not be an experimental artifact. In order to ascertain this point several agents or conditions have been tested, all leading to an increase of pCa, with respect to the value observed in state-4 mitochondria : (a) addition of uncoupling agents which originate H f leaks [28]; (b) addition of valinomycin which originates a K + current of variable magnitude depending on the K + concentration (Fig. 1); (c) addition of respiratory inhibitors which depress the rate of e-flow and therefore of H + pumping (Fig.…”

Section: The Relationship Between Pca and A$mentioning

confidence: 99%

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Regulation of Ca²⁺ Efflux in Rat Liver Mitochondria

Bernardi

Azzone

1983

European Journal of Biochemistry

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1. The paper analyzes the relationship between membrane potential (A$), steady state pCa, (-log [Ca"] in the outer aqueous phase) and rate of ruthenium-red-induced Ca2+ efflux in liver mitochondria. Energized liver mitochondria maintain a pCa, of about 6.0 in the presence of 1.5 mM Mg2+ and 0.5 mM Pi. A slight depression of A $ results in net Ca2+ uptake leading to an increased steady state pCa,. On the other hand, a more marked depression of A$ results in net Ca2+ efflux, leading to a decreased steady-state pCa,. These results reflect a biphasic relationship between A $ and pCa,, in that pCa, increases with the increase of A $ up to a value of about 130 mV, whereas a further increase of A$ above 130 mV results in a decrease of pCa,. The phenomenon of Ca2+ uptake fobwing a depression of A $ is independent of the tool used to affect A $ whether by inward K + current via valinomycin, or by inward H + current through protonophores or through F,-ATP synthase, or by restriction of eflow.2. The pathway for Ca2+ efflux is considerably activated by stretching of the inner membrane in hypotonic media. This activation is accompanied by a decreased pCa, at steady state and by an increased rate of ruthenium-redinduced Ca2+ efflux. By restricting the rate of e-flow in hypotonically treated mitochondria, a marked dependence of the rate of ruthenium-red-induced Caz+ efflux on the value of A I ,~ is observed, in that the rate of Ca2+ efflux increases with the value of A$. The pCa, is linearly related to the rate of Ca" efflux.3. Activation of oxidative phosphorylation via addition of hexokinase + glucose to ATP-supplemented mitochondria, is followed by a phase of CaZf uptake, which is reversed by atractyloside.4. These findings support the view that Ca2+ efflux in steady state mitochondria occurs through an independent, d $-controlled pathway and that changes of A $ during oxidative phosphorylation can effectively modulate mitochondrial Ca2+ distribution by inhibiting or activating the A$-controlled CaZ + efflux pathway.Increasing evidence suggests that Ca2+ ions play a key role in the regulation of intracellular metabolic processes [l, 21. The possible role of mitochondria in regulating intracellular Ca2

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Section: Activirtion Of the Ejflux Puthwuy By Hypotonic Swelling And supporting

confidence: 73%

Section: Resultsmentioning

confidence: 82%

Section: Activirtion Of the Ejflux Puthwuy By Hypotonic Swelling And mentioning

confidence: 99%

Section: The Relationship Between Pca and A$mentioning

confidence: 99%

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Regulation of Ca²⁺ Efflux in Rat Liver Mitochondria

Bernardi

Azzone

1983

European Journal of Biochemistry

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“…The influx is sensitive to ruthenium red [24-271 and has been shown to be under the control of AE [28,29].…”

Section: 3mentioning

confidence: 99%

An electrogenic uniport mediates light‐dependent Ca²⁺ influx into intact spinach chloroplasts

1985

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Light-dependent Ca2+ influx into intact spinach chloroplasts, measured with the metallochromic indicator arsenazo III, is stimulated by uncouplers (FCCP, CCCP, nigericin) and inhibited by ruthenium red. The data presented demonstrate that light-dependent Ca 2+ influx into chloroplasts is electrogenic and mediated by a uniport-type carrier. The characteristics of the carrier system are similar to those of the Caz+ uniport of mitochondria.Spinach Chloroplast Ca2+

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Intracellular Calcium Homeostasis with Extrapolations to Cardiac Ischemia

et al. 1983

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A membrane potential‐modulated pathway for Ca²⁺ efflux in rat liver mitochondria

Cited by 46 publications

References 18 publications

Regulation of Ca²⁺ Efflux in Rat Liver Mitochondria

Regulation of Ca²⁺ Efflux in Rat Liver Mitochondria

An electrogenic uniport mediates light‐dependent Ca²⁺ influx into intact spinach chloroplasts

Intracellular Calcium Homeostasis with Extrapolations to Cardiac Ischemia

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A membrane potential‐modulated pathway for Ca2+ efflux in rat liver mitochondria

Cited by 46 publications

References 18 publications

Regulation of Ca2+ Efflux in Rat Liver Mitochondria

Regulation of Ca2+ Efflux in Rat Liver Mitochondria

An electrogenic uniport mediates light‐dependent Ca2+ influx into intact spinach chloroplasts

Intracellular Calcium Homeostasis with Extrapolations to Cardiac Ischemia

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About

A membrane potential‐modulated pathway for Ca²⁺ efflux in rat liver mitochondria

Regulation of Ca²⁺ Efflux in Rat Liver Mitochondria

Regulation of Ca²⁺ Efflux in Rat Liver Mitochondria

An electrogenic uniport mediates light‐dependent Ca²⁺ influx into intact spinach chloroplasts