Content and binding characteristics of the mitochondrial ATPase inhibitor, IF1 in the tissues of several slow and fast heart-rate homeothermic species and in two poikilotherms

Rouslin, William; Frank, Gerald D.; Broge, Charles W.

doi:10.1007/bf02110339

Cited by 28 publications

(32 citation statements)

References 27 publications

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“…This raises the question of whether inhibition of the F 1 F OATPase or decreased delivery of nucleotides into the mitochondrial matrix by the adenine nucleotide translocase contributes to the impaired oxidative phosphorylation and ATP depletion present in the unprotected tubules after H/R and limits the effect of ATP on mitochondrial energization in the tubules when they are subsequently permeabilized for the safranin O uptake studies. Decreases of both F 1 F O -ATPase and adenine nucleotide translocase activity have been reported in isolated mitochondria after ischemia and related insults (23)(24)(25)(26)(27)(28). Although it preserves ⌬⌿ m , ATP hydrolysis by the F 1 F O -ATPase Figure 7.…”

Section: Discussionmentioning

confidence: 93%

“…Movement of protons back into the matrix via the F 1 F O -ATPase then drives phosphorylation of ATP (9,10,20,21) (Figure 11). When electron transport is inhibited, ⌬⌿ m is low, and ATP is available, the F 1 F O -ATPase works in reverse to hydrolyze ATP to extrude protons and restore ⌬⌿ m (16,22,23) (Figure 11). In these studies, we have used these processes as expressed in the permeabilized tubules to further define the factors contributing to the impaired recovery of ⌬⌿ m after H/R and to assess F 1 F O -ATPase function.…”

Section: Discussionmentioning

confidence: 99%

“…is energetically unfavorable for the cell, because it will tend to further deplete ATP generated by glycolysis or less damaged mitochondria (16,23). It is regulated by reversible, low-pHinduced binding to the F 1 F O -ATPase under de-energized conditions of an F 1 F O -ATPase inhibitory subunit, IF 1 , which inhibits activity during ischemia and thereby conserves ATP (23,24).…”

Section: Discussionmentioning

confidence: 99%

“…It is regulated by reversible, low-pHinduced binding to the F 1 F O -ATPase under de-energized conditions of an F 1 F O -ATPase inhibitory subunit, IF 1 , which inhibits activity during ischemia and thereby conserves ATP (23,24). The content of IF 1 and degree of inhibition of the F 1 F O -ATPase during ischemia varies between tissues and species (23). The NADH-coupled assay for oligomycin-sensitive ATPase using frozen/thawed tubules demonstrated moderate inhibition at the end of hypoxia, which recovered during reoxygenation ( Figure 10, left panel).…”

Section: Discussionmentioning

confidence: 99%

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F 1 F O-ATPase Activity and ATP Dependence of Mitochondrial Energization in Proximal Tubules after Hypoxia/Reoxygenation

Feldkamp¹,

Kribben²,

Weinberg³

2005

Journal of the American Society of Nephrology

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F reshly isolated proximal tubules subjected to hypoxia/ reoxygenation (H/R) (1) develop a severe mitochondrial functional deficit (1,2) leading to persistent ATP depletion, which plays a pivotal role in overall cellular recovery (3). The energetic deficit occurs despite preserved electron transport (4) and minimal cytochrome c release (2). ATP recovery can be substantially improved by supplementing tubules with citric acid cycle metabolites such as ␣-ketoglutarate and malate individually and in combination (1-3).Mitochondrial membrane potential (⌬⌿ m ), as assessed by 5,5Ј,6,6Ј-tetrachloro-1,1Ј,3,3Ј-tetraethylbenzimidazocarbocyanine iodide (JC-1) uptake is consistently decreased, but not absent, in affected tubules and is restored by the protective citric acid cycle metabolites (1,2,4,5). However, the nonlinearity of formation of JC-1 red aggregates relative to ⌬⌿ m and their slow and incomplete dissociation back to monomers during de-energization limits the use of JC-1 to dynamically follow and manipulate the changes of ⌬⌿ m to gain more mechanistic information about the factors contributing to them (5). Safranin O is concentrated in the mitochondrial matrix as a linear function of ⌬⌿ m where its fluorescence is quenched, allowing its uptake and ⌬⌿ m to be followed by fluorescence changes (6-8). We have recently reported studies employing safranin O in digitonin-permeabilized tubule preparations to alternatively assess ⌬⌿ m in the model (5). Safranin O uptake by mitochondria in digitonin-permeabilized tubules required very small amounts of tubules, permitted measurements of ⌬⌿ m for relatively prolonged periods after the end of the experimental maneuvers, was rapidly reversible during de-energization, and allowed for direct assessment of both substrate-dependent, electron transport-mediated ⌬⌿ m and ATP hydrolysis-supported ⌬⌿ m . Both types of energization in mitochondria of permeabilized tubules measured using safranin O after H/R were impaired. Combining substrates and ATP substantially restored ⌬⌿ m , but did not fully normalize it (5). The objective of the studies reported here was to clarify the mechanism for the energetic deficit by further investigating the role of ATP in facilitating recovery of mitochondrial energization after H/R and determining whether abnormalities of the mitochondrial F 1 F O -ATPase (9,10) or of nucleotide delivery to it by the adenine nucleotide translocase are involved.

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Section: Discussionmentioning

confidence: 93%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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F 1 F O-ATPase Activity and ATP Dependence of Mitochondrial Energization in Proximal Tubules after Hypoxia/Reoxygenation

Feldkamp¹,

Kribben²,

Weinberg³

2005

Journal of the American Society of Nephrology

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“…This would conceivably be visualized polarographically as elevated oxygen consumption in state 4/4 ol . Note that while hypoxia-tolerant species are able to reduce ATP hydrolysis by inhibiting ATP synthase and thus can withstand hypoxic conditions longer, hypoxia-sensitive ectothermic species lack this ability (Rouslin et al, 1995) and rapidly experience catastrophic cellular energy imbalance that can lead to cell death.…”

Section: Research Articlementioning

confidence: 99%

Hypoxia-cadmium interactions on rainbow trout (Oncorhynchus mykiss) mitochondrial bioenergetics: attenuation of hypoxia-induced proton leak by low doses of cadmium

Onukwufor

MacDonald

Kibenge

et al. 2013

Journal of Experimental Biology

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The goal of the present study was to elucidate the modulatory effects of cadmium (Cd) on hypoxia/reoxygenation-induced mitochondrial dysfunction in light of the limited understanding of the mechanisms of multiple stressor interactions in aquatic organisms. Rainbow trout (Oncorhynchus mykiss) liver mitochondria were isolated and energized with complex I substrates (malate-glutamate), and exposed to hypoxia (0>P O 2 <2 Torr) for 0-60 min followed by reoxygenation and measurement of coupled and uncoupled respiration and complex I enzyme activity. Thereafter, 5 min hypoxia was used to probe interactions with Cd (0-20 μmol l) and to test the hypothesis that deleterious effects of hypoxia/reoxygenation on mitochondria were mediated by reactive oxygen species (ROS). Hypoxia/reoxygenation inhibited state 3 and uncoupler-stimulated (state 3u) respiration while concomitantly stimulating states 4 and 4 ol (proton leak) respiration, thus reducing phosphorylation and coupling efficiencies. Low doses of Cd (≤5 μmol l −1 ) reduced, while higher doses enhanced, hypoxia-stimulated proton leak. This was in contrast to the monotonic enhancement by Cd of hypoxia/reoxygenationinduced reductions of state 3 respiration, phosphorylation efficiency and coupling. Mitochondrial complex I activity was inhibited by hypoxia/reoxygenation, hence confirming the impairment of at least one component of the electron transport chain (ETC) in rainbow trout mitochondria. Similar to the effect on state 4 and proton leak, low doses of Cd partially reversed the hypoxia/reoxygenation-induced complex I activity inhibition. The ROS scavenger and sulfhydryl group donor N-acetylcysteine, administrated immediately prior to hypoxia exposure, reduced hypoxia/reoxygenation-stimulated proton leak without rescuing the inhibited state 3 respiration, suggesting that hypoxia/reoxygenation influences distinct aspects of mitochondria via different mechanisms. Our results indicate that hypoxia/reoxygenation impairs the ETC and sensitizes mitochondria to Cd via mechanisms that involve, at least in part, ROS. Moreover, we provide, for the first time in fish, evidence for a hormetic effect of Cd on mitochondrial bioenergetics -the attenuation of hypoxia/reoxygenation-stimulated proton leak and partial rescue of complex I inhibition by low Cd doses.

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ATPase activity, IF1 content, and proton conductivity of ESMP from control and ischemic slow and fast heart-rate hearts

Rouslin

Broge

Guerrieri

et al. 1995

J Bioenerg Biomembr

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Earlier studies by Rouslin and coworkers showed that, during myocardial ischemia in slow heart-rate species which include rabbits and all larger mammals examined including humans, there is an IF1-mediated inhibition of the mitochondrial ATPase due to an increase in the amount of IF1 bound to the ATPase (Rouslin, W., and Pullman, M.E., J. Mol. Cell. Cardiol. 19,661-668, 1987). Earlier work by Guerrieri and colleagues demonstrated that IF1 binding to bovine heart ESMP was accompanied by parallel decreases in ATPase activity and in passive proton conduction (Guerrieri, F., et al., FEBS Lett. 213, 67-72, 1987). In the present study rabbit was used as the slow heart-rate species and rat as the fast heart-rate species. Rat is a fast heart-rate species that contains too little IF1 to down regulate the ATPase activity present. Mitochondria were prepared from control and ischemic hearts and ESMP were made from aliquots by sonication at pH 8.0 with 2 mM EDTA. Oligomycin-sensitive ATPase activity and IF1 content were measured in SMP prepared from the control and ischemic mitochondrial samples. After identical incubation procedures, oligomycin-sensitive ATPase activity, oligomycin-sensitive proton conductivity, and IF1 content were also measured in ESMP samples. The study was undertaken to corroborate further what appear to be fundamental differences in ATPase regulation between slow and fast heart-rate mammalian hearts evident during total myocardial ischemia. Thus, passive proton conductivity was used as an independent measure of these regulatory differences. The results show that, consistent with the low IF1 content of rat heart cardiac muscle mitochondria, control rat heart ESMP exhibit approximately twice as much passive proton conductivity as control rabbit heart ESMP regardless of the pH of the incubation and assay. Moreover, while total ischemia caused an increase in IF1 binding and a commensurate decrease in passive proton conductivity in rabbit heart ESMP regardless of pH, neither IF1 content nor proton conductivity changed significantly in rat heart ESMP as a result of ischemia.

show abstract

Content and binding characteristics of the mitochondrial ATPase inhibitor, IF1 in the tissues of several slow and fast heart-rate homeothermic species and in two poikilotherms

Cited by 28 publications

References 27 publications

F 1 F O-ATPase Activity and ATP Dependence of Mitochondrial Energization in Proximal Tubules after Hypoxia/Reoxygenation

F 1 F O-ATPase Activity and ATP Dependence of Mitochondrial Energization in Proximal Tubules after Hypoxia/Reoxygenation

Hypoxia-cadmium interactions on rainbow trout (Oncorhynchus mykiss) mitochondrial bioenergetics: attenuation of hypoxia-induced proton leak by low doses of cadmium

ATPase activity, IF1 content, and proton conductivity of ESMP from control and ischemic slow and fast heart-rate hearts

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