Differences in nucleotide compartmentation and energy state in isolated and in situ rat heart: Assessment by 31P-NMR spectroscopy

Williams, John P.; Headrick, John P.

doi:10.1016/0005-2728(96)00036-9

Cited by 22 publications

(14 citation statements)

References 33 publications

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“…In support of this, 31 P-NMR CK-flux measurements with transgenic mice showing graded reductions of MM-CK expression in their muscles, revealed a strikingly unexpected, "anomalous" CK-flux behaviour [23], indicating that some flux through CK, presumably bound CK, and possibly also some PCr and/or ATP, is NMR-invisible or otherwise not amenable to this analysis [24,25]. In the meantime, more evidence from NMR-measurements [8,9,12,27], as well as from recent in vivo 14 [C]Cr-tracer studies [4], is accumulting in favour of compartmentation of the CK system and for the existence of different pools of CK substrates.…”

mentioning

confidence: 83%

Some new aspects of creatine kinase (CK): compartmentation, structure, function and regulation for cellular and mitochondrial bioenergetics and physiology

Wallimann¹,

Dolder²,

Schlattner³

et al. 1998

BioFactors

209

120

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Creatine kinase (CK) isoenzymes, specifically located at places of energy demand and energy production, are linked by a phosphocreatine/creatine (PCr/Cr) circuit, found in cells with intermittently high energy demands. Cytosolic CKs, in close conjunction with Ca(2+)-pumps, play a crucial role for the energetics of Ca(2+)-homeostasis. Mitochondrial Mi-CK, a cuboidal-shaped octamer with a central channel, binds and crosslinks mitochondrial membranes and forms a functionally coupled microcompartment with porin and adenine nucleotide translocase for vectorial export of PCr into the cytosol. The CK system is regulated by AMP-activated protein kinase via PCr/Cr and ATP/AMP ratios. Mi-CK stabilizes and cross-links cristae- or inner/outer membranes to form parallel membrane stacks and, if overexpressed due to creatine depletion or cellular energy stress, forms those crystalline intramitochondrial inclusions seen in some mitochondrial cytopathy patients. Mi-CK is a prime target for free radical damage by peroxynitrite. Mi-CK octamers, together with CK substrates have a marked stabilizing and protective effect against mitochondrial permeability transition pore opening, thus providing a rationale for creatine supplementation of patients with neuromuscular and neurodegenerative diseases.

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mentioning

confidence: 83%

Some new aspects of creatine kinase (CK): compartmentation, structure, function and regulation for cellular and mitochondrial bioenergetics and physiology

Wallimann¹,

Dolder²,

Schlattner³

et al. 1998

BioFactors

209

120

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“…In wild type mouse heart tissue, ATP content was found to be 4.68 ± 1.11 nmol/mg of wet weight, which is consistent with that previously measured in rat heart tissue by 31 P NMR. [45][46][47][48][49] Acetyl-CoA is a key energy metabolite that is produced in vivo via two main pathways: fatty acid β-oxidation and pyruvate decarboxylation.…”

Section: Metabolomic Analysis Of Mouse Tissue Extractmentioning

confidence: 99%

Shotgun Metabolomics Approach for the Analysis of Negatively Charged Water-Soluble Cellular Metabolites from Mouse Heart Tissue

et al. 2007

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A shotgun metabolomics approach using MALDI-TOF/TOF mass spectrometry was developed for the rapid analysis of negatively charged water-soluble cellular metabolites. Through the use of neutral organic solvents to inactivate endogenous enzyme activities (i.e., methanol/chloroform/H2O extraction), in conjunction with a matrix having minimal background noise (9-amnioacridine), a set of multiplexed conditions was developed that allowed identification of 285 peaks corresponding to negatively charged metabolites from mouse heart extracts. Identification of metabolite peaks was based on mass accuracy and was confirmed by tandem mass spectrometry for 90 of the identified metabolite peaks. Through multiplexing ionization conditions, new suites of metabolites could be ionized and "spectrometric isolation" of closely neighboring peaks for subsequent tandem mass spectrometric interrogation could be achieved. Moreover, assignments of ions from isomeric metabolites and quantitation of their relative abundance was achieved in many cases through tandem mass spectrometry by identification of diagnostic fragmentation ions (e.g., discrimination of ATP from dGTP). The high sensitivity of this approach facilitated the detection of extremely low abundance metabolites including important signaling metabolites such as IP3, cAMP, and cGMP. Collectively, these results identify a multiplexed MALDI-TOF/TOF MS approach for analysis of negatively charged metabolites in mammalian tissues.

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“…The levels of ATP, CrP, and P i were determined using 31 P NMR spectroscopy comparing respective peak areas with peak area of 250 nmol of methylene diphosphonate used as an internal standard (23).…”

Section: P Nmr Spectroscopy-mentioning

confidence: 99%

Compromised Energetics in the Adenylate Kinase AK1Gene Knockout Heart under Metabolic Stress

Pucar

Janssen

Dzeja

et al. 2000

Journal of Biological Chemistry

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Rapid exchange of high energy carrying molecules between intracellular compartments is essential in sustaining cellular energetic homeostasis. Adenylate kinase (AK)-catalyzed transfer of adenine nucleotide ␤-and ␥-phosphoryls has been implicated in intracellular energy communication and nucleotide metabolism. To demonstrate the significance of this reaction in cardiac energetics, phosphotransfer dynamics were determined by [18 O]phosphoryl oxygen analysis using 31 P NMR and mass spectrometry. In hearts with a null mutation of the AK1 gene, which encodes the major AK isoform, total AK activity and ␤-phosphoryl transfer was reduced by 94% and 36%, respectively. This was associated with up-regulation of phosphoryl flux through remaining minor AK isoforms and the glycolytic phosphotransfer enzyme, 3-phosphoglycerate kinase. In the absence of metabolic stress, deletion of AK1 did not translate into gross abnormalities in nucleotide levels, ␥-ATP turnover rate or creatine kinase-catalyzed phosphotransfer. However, under hypoxia AK1-deficient hearts, compared with the wild type, had a blunted AK-catalyzed phosphotransfer response, lowered intracellular ATP levels, increased P i /ATP ratio, and suppressed generation of adenosine. Thus, although lack of AK1 phosphotransfer can be compensated in the absence of metabolic challenge, under hypoxia AK1-knockout hearts display compromised energetics and impaired cardioprotective signaling. This study, therefore, provides first direct evidence that AK1 is essential in maintaining myocardial energetic homeostasis, in particular under metabolic stress. Adenylate kinase (AK)1 catalyzes reversible phosphotransfer, 2 ADP 7 AMP ϩ ATP, and participates in de novo synthesis, regeneration and salvage of adenine nucleotides (1-5). AK is particularly abundant in tissues with high energy turnover, where it facilitates transfer of energy-rich ␤-and ␥-phosphoryls and regulates vital ATP-dependent cellular processes (6 -10).In fact, AK may serve as an integral component of phosphotransfer networks, along with creatine kinase (CK) and glycolysis, effectively coupling ATP-generating with ATP-consuming or ATP-sensing intracellular sites (11-15).In the heart, CK-catalyzed phosphotransfer is the major pathway that can transfer high energy phosphoryls derived from the ␥-phosphoryl of ATP (10, 16 -18). Although less active than CK, AK catalysis provides a unique mechanism for transfer and utilization of both ␥-and ␤-phosphoryls in the ATP molecule (10, 15). In this way, AK-catalyzed phosphotransfer doubles the energetic potential of ATP and could provide an additional energetic source under conditions of increased energy demand (10, 19). However, due to lack of membrane permeant and selective AK inhibitors, the biological importance of AK in heart muscle and its role in sustaining myocardial energetics under conditions of metabolic stress have not been established.We have recently demonstrated that deletion of the AK1 gene, which encodes the major AK isoform, produces a phenotype with reduced skelet...

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Differences in nucleotide compartmentation and energy state in isolated and in situ rat heart: Assessment by 31P-NMR spectroscopy

Cited by 22 publications

References 33 publications

Some new aspects of creatine kinase (CK): compartmentation, structure, function and regulation for cellular and mitochondrial bioenergetics and physiology

Some new aspects of creatine kinase (CK): compartmentation, structure, function and regulation for cellular and mitochondrial bioenergetics and physiology

Shotgun Metabolomics Approach for the Analysis of Negatively Charged Water-Soluble Cellular Metabolites from Mouse Heart Tissue

Compromised Energetics in the Adenylate Kinase AK1Gene Knockout Heart under Metabolic Stress

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