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Anishkin A, Adepu KK, Bhandari D, Adams SH, Chintapalli SV. Computational Analysis Reveals Unique Binding Patterns of Oxygenated and Deoxygenated Myoglobin to the Outer Mitochondrial Membrane. Biomolecules 2023; 13:1138. [PMID: 37509174 PMCID: PMC10377724 DOI: 10.3390/biom13071138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 06/26/2023] [Accepted: 07/13/2023] [Indexed: 07/30/2023] Open
Abstract
Myoglobin (Mb) interaction with the outer mitochondrial membrane (OMM) promotes oxygen (O2) release. However, comprehensive molecular details on specific contact regions of the OMM with oxygenated (oxy-) and deoxygenated (deoxy-)Mb are missing. We used molecular dynamics (MD) simulations to explore the interaction of oxy- and deoxy-Mb with the membrane lipids of the OMM in two lipid compositions: (a) a typical whole membrane on average, and (b) specifically the cardiolipin-enriched cristae region (contact site). Unrestrained relaxations showed that on average, both the oxy- and deoxy-Mb established more stable contacts with the lipids typical of the cristae contact site, then with those of the average OMM. However, in steered detachment simulations, deoxy-Mb clung more tightly to the average OMM, and oxy-Mb strongly preferred the contact sites of the OMM. The MD simulation analysis further indicated that a non-specific binding, mediated by local electrostatic interactions, existed between charged or polar groups of Mb and the membrane, for stable interaction. To the best of our knowledge, this is the first computational study providing the molecular details of the direct Mb-mitochondria interaction that assisted in distinguishing the preferred localization of oxy- and deoxy-Mb on the OMM. Our findings support the existing experimental evidence on Mb-mitochondrial association and shed more insights on Mb-mediated O2 transport for cellular bioenergetics.
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Affiliation(s)
- Andriy Anishkin
- Department of Biology, University of Maryland, College Park, MD 20742, USA
| | - Kiran Kumar Adepu
- Arkansas Children's Nutrition Center, Little Rock, AR 72202, USA
- Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | | | - Sean H Adams
- Department of Surgery, School of Medicine, University of California Davis, Sacramento, CA 95616, USA
- Center for Alimentary and Metabolic Science, University of California Davis, Sacramento, CA 95616, USA
| | - Sree V Chintapalli
- Arkansas Children's Nutrition Center, Little Rock, AR 72202, USA
- Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
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Adepu KK, Bhandari D, Anishkin A, Adams SH, Chintapalli SV. Myoglobin Interaction with Lactate Rapidly Releases Oxygen: Studies on Binding Thermodynamics, Spectroscopy, and Oxygen Kinetics. Int J Mol Sci 2022; 23:ijms23094747. [PMID: 35563138 PMCID: PMC9103699 DOI: 10.3390/ijms23094747] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 04/22/2022] [Accepted: 04/24/2022] [Indexed: 01/27/2023] Open
Abstract
Myoglobin (Mb)-mediated oxygen (O2) delivery and dissolved O2 in the cytosol are two major sources that support oxidative phosphorylation. During intense exercise, lactate (LAC) production is elevated in skeletal muscles as a consequence of insufficient intracellular O2 supply. The latter results in diminished mitochondrial oxidative metabolism and an increased reliance on nonoxidative pathways to generate ATP. Whether or not metabolites from these pathways impact Mb-O2 associations remains to be established. In the present study, we employed isothermal titration calorimetry, O2 kinetic studies, and UV-Vis spectroscopy to evaluate the LAC affinity toward Mb (oxy- and deoxy-Mb) and the effect of LAC on O2 release from oxy-Mb in varying pH conditions (pH 6.0–7.0). Our results show that LAC avidly binds to both oxy- and deoxy-Mb (only at acidic pH for the latter). Similarly, in the presence of LAC, increased release of O2 from oxy-Mb was detected. This suggests that with LAC binding to Mb, the structural conformation of the protein (near the heme center) might be altered, which concomitantly triggers the release of O2. Taken together, these novel findings support a mechanism where LAC acts as a regulator of O2 management in Mb-rich tissues and/or influences the putative signaling roles for oxy- and deoxy-Mb, especially under conditions of LAC accumulation and lactic acidosis.
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Affiliation(s)
- Kiran Kumar Adepu
- Arkansas Children’s Nutrition Center, Little Rock, AR 72202, USA;
- Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, AR 72202, USA
- Correspondence: (K.K.A.); (S.V.C.)
| | | | - Andriy Anishkin
- Department of Biology, University of Maryland, College Park, MD 20742, USA;
| | - Sean H. Adams
- Department of Surgery, School of Medicine, University of California, Davis, CA 95616, USA;
- Center for Alimentary and Metabolic Science, University of California, Davis, CA 95616, USA
| | - Sree V. Chintapalli
- Arkansas Children’s Nutrition Center, Little Rock, AR 72202, USA;
- Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, AR 72202, USA
- Correspondence: (K.K.A.); (S.V.C.)
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Gerber L, Clow KA, Driedzic WR, Gamperl AK. The Relationship between Myoglobin, Aerobic Capacity, Nitric Oxide Synthase Activity and Mitochondrial Function in Fish Hearts. Antioxidants (Basel) 2021; 10:antiox10071072. [PMID: 34356305 PMCID: PMC8301165 DOI: 10.3390/antiox10071072] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 06/28/2021] [Accepted: 06/30/2021] [Indexed: 11/24/2022] Open
Abstract
The dynamic interactions between nitric oxide (NO) and myoglobin (Mb) in the cardiovascular system have received considerable attention. The loss of Mb, the principal O2 carrier and a NO scavenger/producer, in the heart of some red-blooded fishes provides a unique opportunity for assessing this globin’s role in NO homeostasis and mitochondrial function. We measured Mb content, activities of enzymes of NO and aerobic metabolism [NO Synthase (NOS) and citrate synthase, respectively] and mitochondrial parameters [Complex-I and -I+II respiration, coupling efficiency, reactive oxygen species production/release rates and mitochondrial sensitivity to inhibition by NO (i.e., NO IC50)] in the heart of three species of red-blooded fish. The expression of Mb correlated positively with NOS activity and NO IC50, with low NOS activity and a reduced NO IC50 in the Mb-lacking lumpfish (Cyclopterus lumpus) as compared to the Mb-expressing Atlantic salmon (Salmo salar) and short-horned sculpin (Myoxocephalus scorpius). Collectively, our data show that NO levels are fine-tuned so that NO homeostasis and mitochondrial function are preserved; indicate that compensatory mechanisms are in place to tightly regulate [NO] and mitochondrial function in a species without Mb; and strongly suggest that the NO IC50 for oxidative phosphorylation is closely related to a fish’s hypoxia tolerance.
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Treberg JR, Martyniuk CJ, Moyes CD. Getting the most out of reductionist approaches in comparative biochemistry and physiology. Comp Biochem Physiol B Biochem Mol Biol 2020; 250:110483. [DOI: 10.1016/j.cbpb.2020.110483] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 07/06/2020] [Accepted: 07/09/2020] [Indexed: 12/17/2022]
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O'Brien KM, Rix AS, Egginton S, Farrell AP, Crockett EL, Schlauch K, Woolsey R, Hoffman M, Merriman S. Cardiac mitochondrial metabolism may contribute to differences in thermal tolerance of red- and white-blooded Antarctic notothenioid fishes. J Exp Biol 2018; 221:jeb177816. [PMID: 29895681 PMCID: PMC6104818 DOI: 10.1242/jeb.177816] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Accepted: 06/04/2018] [Indexed: 12/18/2022]
Abstract
Studies in temperate fishes provide evidence that cardiac mitochondrial function and the capacity to fuel cardiac work contribute to thermal tolerance. Here, we tested the hypothesis that decreased cardiac aerobic metabolic capacity contributes to the lower thermal tolerance of the haemoglobinless Antarctic icefish, Chaenocephalus aceratus, compared with that of the red-blooded Antarctic species, Notothenia coriiceps. Maximal activities of citrate synthase (CS) and lactate dehydrogenase (LDH), respiration rates of isolated mitochondria, adenylate levels and changes in mitochondrial protein expression were quantified from hearts of animals held at ambient temperature or exposed to their critical thermal maximum (CTmax). Compared with C. aceratus, activity of CS, ATP concentration and energy charge were higher in hearts of N. coriiceps at ambient temperature and CTmax While state 3 mitochondrial respiration rates were not impaired by exposure to CTmax in either species, state 4 rates, indicative of proton leakage, increased following exposure to CTmax in C. aceratus but not N. coriiceps The interactive effect of temperature and species resulted in an increase in antioxidants and aerobic metabolic enzymes in N. coriiceps but not in C. aceratus Together, our results support the hypothesis that the lower aerobic metabolic capacity of C. aceratus hearts contributes to its low thermal tolerance.
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Affiliation(s)
- Kristin M O'Brien
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
| | - Anna S Rix
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
| | - Stuart Egginton
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Anthony P Farrell
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4
| | | | - Karen Schlauch
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, NV 89557, USA
| | - Rebekah Woolsey
- Nevada Proteomics Center, University of Nevada, Reno, NV 89557, USA
| | - Megan Hoffman
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
| | - Sean Merriman
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
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O'Brien KM, Crockett EL, Philip J, Oldham CA, Hoffman M, Kuhn DE, Barry R, McLaughlin J. The loss of hemoglobin and myoglobin does not minimize oxidative stress in Antarctic icefishes. ACTA ACUST UNITED AC 2018; 221:jeb.162503. [PMID: 29361578 DOI: 10.1242/jeb.162503] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Accepted: 12/11/2017] [Indexed: 01/07/2023]
Abstract
The unusual pattern of expression of hemoglobin (Hb) and myoglobin (Mb) among Antarctic notothenioid fishes provides an exceptional model system for assessing the impact of these proteins on oxidative stress. We tested the hypothesis that the lack of oxygen-binding proteins may reduce oxidative stress. Levels and activity of pro-oxidants and small-molecule and enzymatic antioxidants, and levels of oxidized lipids and proteins in the liver, oxidative skeletal muscle and heart ventricle were quantified in five species of notothenioid fishes differing in the expression of Hb and Mb. Levels of ubiquitinated proteins and rates of protein degradation by the 20S proteasome were also quantified. Although levels of oxidized proteins and lipids, ubiquitinated proteins, and antioxidants were higher in red-blooded fishes than in Hb-less icefishes in some tissues, this pattern did not persist across all tissues. Expression of Mb was not associated with oxidative damage in the heart ventricle, whereas the activity of citrate synthase and the contents of heme were positively correlated with oxidative damage in most tissues. Despite some tissue differences in levels of protein carbonyls among species, rates of degradation by the 20S proteasome were not markedly different, suggesting either alternative pathways for eliminating oxidized proteins or that redox tone varies among species. Together, our data indicate that the loss of Hb and Mb does not correspond with a clear pattern of either reduced oxidative defense or oxidative damage.
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Affiliation(s)
- Kristin M O'Brien
- Institute of Arctic Biology, University of Alaska, Fairbanks, Alaska, 99775, USA
| | | | - Jacques Philip
- Center for Alaska Native Health Research, University of Alaska, Fairbanks, Alaska, 99775, USA
| | - Corey A Oldham
- Institute of Arctic Biology, University of Alaska, Fairbanks, Alaska, 99775, USA
| | - Megan Hoffman
- Institute of Arctic Biology, University of Alaska, Fairbanks, Alaska, 99775, USA
| | - Donald E Kuhn
- Department of Biological Sciences, Ohio University, Athens, Ohio, 45701, USA
| | - Ronald Barry
- Department of Mathematics and Statistics, University of Alaska, Fairbanks, Alaska, 99775, USA
| | - Jessica McLaughlin
- Institute of Arctic Biology, University of Alaska, Fairbanks, Alaska, 99775, USA
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Helbo S, Fago A, Gesser H. Myoglobin-dependent O2 consumption of the hypoxic trout heart. Comp Biochem Physiol A Mol Integr Physiol 2013; 165:40-5. [DOI: 10.1016/j.cbpa.2013.01.020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Revised: 01/14/2013] [Accepted: 01/17/2013] [Indexed: 11/29/2022]
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Helbo S, Weber RE, Fago A. Expression patterns and adaptive functional diversity of vertebrate myoglobins. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2013; 1834:1832-9. [PMID: 23388387 DOI: 10.1016/j.bbapap.2013.01.037] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Revised: 01/23/2013] [Accepted: 01/26/2013] [Indexed: 02/06/2023]
Abstract
Recent years have witnessed a new round of research on one of the most studied proteins - myoglobin (Mb), the oxygen (O2) carrier of skeletal and heart muscle. Two major discoveries have stimulated research in this field: 1) that Mb has additional protecting functions, such as the regulation of in vivo levels of the signaling molecule nitric oxide (NO) by scavenging and generating NO during normoxia and hypoxia, respectively; and 2) that Mb in vertebrates (particularly fish) is expressed as tissue-specific isoforms in other tissues than heart and skeletal muscle, such as vessel endothelium, liver and brain, as found in cyprinid fish. Furthermore, Mb has also been found to protect against oxidative stress after hypoxia and reoxygenation and to undergo allosteric, O2-linked S-nitrosation, as in rainbow trout. Overall, the emerging evidence, particularly from fish species, indicates that Mb fulfills a broader array of physiological functions in a wider range of different tissues than hitherto appreciated. This new knowledge helps to better understand how variations in Mb structure and function may correlate with differences in animals' lifestyles and hypoxia-tolerance. This review integrates old and new results on Mb expression patterns and functional properties amongst vertebrates and discusses how these may relate to adaptive variations in different species. This article is part of a special issue entitled: Oxygen Binding and Sensing Proteins.
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Affiliation(s)
- Signe Helbo
- Department of Bioscience, Aarhus University, Denmark.
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Lague SL, Speers-Roesch B, Richards JG, Farrell AP. Exceptional cardiac anoxia tolerance in tilapia (Oreochromis hybrid). ACTA ACUST UNITED AC 2012; 215:1354-65. [PMID: 22442374 DOI: 10.1242/jeb.063362] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Anoxic survival requires the matching of cardiac ATP supply (i.e. maximum glycolytic potential, MGP) and demand (i.e. cardiac power output, PO). We examined the idea that the previously observed in vivo downregulation of cardiac function during exposure to severe hypoxia in tilapia (Oreochromis hybrid) represents a physiological strategy to reduce routine PO to within the heart's MGP. The MGP of the ectothermic vertebrate heart has previously been suggested to be ∼70 nmol ATP s(-1) g(-1), sustaining a PO of ∼0.7 mW g(-1) at 15°C. We developed an in situ perfused heart preparation for tilapia (Oreochromis hybrid) and characterized the routine and maximum cardiac performance under both normoxic (>20 kPa O(2)) and severely hypoxic perfusion conditions (<0.20 kPa O(2)) at pH 7.75 and 22°C. The additive effects of acidosis (pH 7.25) and chemical anoxia (1 mmol l(-1) NaCN) on cardiac performance in severe hypoxia were also examined. Under normoxic conditions, cardiac performance and myocardial oxygen consumption rate were comparable to those of other teleosts. The tilapia heart maintained a routine normoxic cardiac output (Q) and PO under all hypoxic conditions, a result that contrasts with the hypoxic cardiac downregulation previously observed in vivo under less severe conditions. Thus, we conclude that the in vivo downregulation of routine cardiac performance in hypoxia is not needed in tilapia to balance cardiac energy supply and demand. Indeed, the MGP of the tilapia heart proved to be quite exceptional. Measurements of myocardial lactate efflux during severe hypoxia were used to calculate the MGP of the tilapia heart. The MGP was estimated to be 172 nmol ATP s(-1) g(-1) at 22°C, and allowed the heart to generate a PO(max) of at least ∼3.1 mW g(-1), which is only 30% lower than the PO(max) observed with normoxia. Even with this MGP, the additional challenge of acidosis during severe hypoxia decreased maximum ATP turnover rate and PO(max) by 30% compared with severe hypoxia alone, suggesting that there are probably direct effects of acidosis on cardiac contractility. We conclude that the high maximum glycolytic ATP turnover rate and levels of PO, which exceed those measured in other ectothermic vertebrate hearts, probably convey a previously unreported anoxia tolerance of the tilapia heart, but a tolerance that may be tempered in vivo by the accumulation of acidotic waste during anoxia.
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Affiliation(s)
- Sabine L Lague
- Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver, BC, Canada, V6T 1Z4.
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Lurman GJ, Koschnick N, Pörtner HO, Lucassen M. Molecular characterisation and expression of Atlantic cod (Gadus morhua) myoglobin from two populations held at two different acclimation temperatures. Comp Biochem Physiol A Mol Integr Physiol 2007; 148:681-9. [PMID: 17884647 DOI: 10.1016/j.cbpa.2007.08.021] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2007] [Revised: 08/17/2007] [Accepted: 08/22/2007] [Indexed: 10/22/2022]
Abstract
Much previous research has demonstrated the plasticity of myoglobin concentrations in both cardiac and skeletal myocytes in response to hypoxia and training. No study has yet looked at the effect of thermal acclimation on myoglobin in fish. Atlantic cod (Gadus morhua) from two different populations, i.e. the North Sea and the North East Arctic, were acclimated to 10 and 4 degrees C. Both the myoglobin mRNA and myoglobin protein in cod hearts increased significantly by up to 3.7 and 2.3 fold respectively as a result of acclimation to 4 degrees C. These increments were largest in the Arctic population, which in earlier studies have been shown to possess cold compensated metabolic demands at low temperatures. These metabolic demands associated with higher mitochondrial capacities may have driven the increase in cardiac myoglobin concentrations, in order to support diffusive oxygen supply. At the same time the increase in myoglobin levels may serve further functions during cold acclimation, for example, protection of the cell against reactive oxygen species, and scavenging nitric oxide, thereby contributing to the regulation of mitochondrial volume density.
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Affiliation(s)
- Glenn J Lurman
- Alfred-Wegener-Institut fuer Polar-und Meeresforschung, Am Handelshafen 12, 27570, Bremerhaven, Germany.
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Castilho PC, Landeira-Fernandez AM, Morrissette J, Block BA. Elevated Ca2+ ATPase (SERCA2) activity in tuna hearts: comparative aspects of temperature dependence. Comp Biochem Physiol A Mol Integr Physiol 2007; 148:124-32. [PMID: 17566775 DOI: 10.1016/j.cbpa.2007.03.033] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2006] [Revised: 03/26/2007] [Accepted: 03/30/2007] [Indexed: 11/17/2022]
Abstract
Tunas have an extraordinary physiology including elevated metabolic rates and high cardiac performance. In some species, retention of metabolic heat warms the slow oxidative swimming muscles and visceral tissues. In all tunas, the heart functions at ambient temperature. Enhanced rates of calcium transport in tuna myocytes are associated with increased expression of proteins involved in the contraction-relaxation cycle. The cardiac SR Ca2+-ATPase (SERCA2) plays a major role during cardiac excitation-contraction (E-C) coupling. Measurements of oxalate-supported Ca2+-uptake in atrial SR vesicles isolated from four species of tunas indicate that bluefin have at least two fold higher Ca2+-uptake than all other tunas examined between 5 and 30 degrees C. The highest atrial Ca2+-uptake was measured in bluefin tuna at 30 degrees C (23.32+/-1.58 nmol Ca2+/mg/min). Differences among tunas in the temperature dependency of Ca2+-uptake were similar for ATP hydrolysis. Western blot analysis revealed a significant increase in SERCA2 content associated with higher Ca2+ uptake rates in the atrial tissues of bluefin tuna and similar RyR expression across species. We propose that the expression of EC coupling proteins in cardiac myocytes, and the higher rates of SERCA2 activity are an important evolutionary step for the maintenance of higher heart rates and endothermy in bluefin tuna.
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Affiliation(s)
- Pedro C Castilho
- Tuna Research and Conservation Center, Hopkins Marine Station, Stanford University, Pacific Grove, California 93950, USA.
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Grove TJ, Sidell BD. Myoglobin deficiency in the hearts of phylogenetically diverse temperate-zone fish species. CAN J ZOOL 2002. [DOI: 10.1139/z02-071] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Previous studies relying upon spectrophotometric methods reported low levels of myoglobin, an intracellular oxygen-binding protein, in oxidative muscles of some sluggish benthic fishes distributed throughout the North Atlantic Ocean. Using immunochemical techniques we show that myoglobin is not expressed in the heart ventricles of Cyclop terus lumpus (Cyclopteridae), Anarhichas lupus (Anarhichadidae), Macrozoarces americanus (Zoarcidae), and Lophius americanus (Lophiidae). Hemitripterus americanus (Hemitripteridae) expresses myoglobin at 2.3 ± 0.2 mg·g wet mass1(mean ± SD). Myoglobin was not detected in oxidative skeletal muscle (pectoral adductor profundus) in either the white-hearted fishes examined or red-hearted H. americanus. Supporting these results, myoglobin messenger RNA was not detected in cardiac muscles of white-hearted fishes by means of either direct Northern blot analysis or by the reverse transcriptase polymerase chain reaction followed by amplification of cDNA product. The partial cDNA sequence of H. americanus myoglobin was determined and shows 86.9% identity with a known teleost myoglobin cDNA from Chionodraco rastrospinosus. The 3' untranslated region of H. americanus is 255 nucleotides longer than the 3' untranslated region of C. rastrospinosus. Comparisons of the deduced amino acid sequence of H. americanus with those of other teleosts show 66.2% sequence identity with Cyprinus carpio, 74.6% with Scomber japonicus, and 80.3% with Thunnus albacares and C. rastrospinosus.
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Harwood CL, Young IS, Altringham JD. How the efficiency of rainbow trout (Oncorhynchus mykiss) ventricular muscle changes with cycle frequency. J Exp Biol 2002; 205:697-706. [PMID: 11907059 DOI: 10.1242/jeb.205.5.697] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARYDifferent species of animals require different cardiac performance and, in turn, their cardiac muscle exhibits different properties. A comparative approach can reveal a great deal about the mechanisms underlying myocardial contraction. Differences in myocardial Ca2+ handling between fish and mammals suggest a greater energy cost of activation in fish. Further, while there is considerable evidence that heart rate (or cycle frequency) should have a profound effect on the efficiency of teleost cardiac muscle, this effect has been largely overlooked. We set out to determine how cycle frequency affects the power output and efficiency of rainbow trout (Oncorhynchus mykiss) ventricular muscle and to relate this to the heart’s function in life. We measured power output and the rate of oxygen consumption (V̇O2) and then calculated efficiency over a physiologically realistic range of cycle frequencies.In contrast to mammalian cardiac muscle, in which V̇O2 increases with increasing heart rate, we found no significant change in V̇O2 in the teleost. However, power output increased by 25 % as cycle frequency was increased from 0.6 to 1.0 Hz, so net and total efficiency increased. A maximum total efficiency of 20 % was achieved at 0.8 Hz, whereas maximum power output occurred at 1.0 Hz. We propose that, since the heart operates continuously, high mechanical efficiency is a major adaptive advantage, particularly at lower heart rates corresponding to the more commonly used slower, sustainable swimming speeds. Efficiency was lower at the higher heart rates required during very fast swimming, which are used during escape or prey capture.If a fixed amount of Ca2+ is released and then resequestered each time the muscle is activated, the activation cost should increase with frequency. We had anticipated that this would have a large effect on the total energy cost of contraction. However, since V̇O2 remains constant, less oxygen is consumed per cycle at high frequencies. We suggest that a constant V̇O2 would be observed if the amount of activator Ca2+ were to decrease with frequency. This decrease in activation energy is consistent with the decrease in the systolic intracellular Ca2+ ([Ca2+]i) transient with increasing stimulation frequency seen in earlier studies.
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Legate NJ, Bailey JR, Driedzic WR. Oxygen consumption in myoglobin-rich and myoglobin-poor isolated fish cardiomyocytes. THE JOURNAL OF EXPERIMENTAL ZOOLOGY 1998; 280:269-76. [PMID: 9493347 DOI: 10.1002/(sici)1097-010x(19980301)280:4<269::aid-jez1>3.0.co;2-m] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The function of myoglobin at the cellular level was investigated by comparing O2 consumption in isolated myoglobin-rich cardiac myocytes from the sea raven (Hemitripterus americanus) and myoglobin-poor myocytes from the ocean pout (Macrozoarces americanus). O2 consumption by sea raven myocytes, 0.21 +/- 0.04 microM O2/10(6) cells.min-1, was significantly higher than O2 consumption by ocean pout myocytes, 0.10 +/- 0.07 microM O2/10(6) cells.min-1 at high PO2. O2 consumption in sea raven myocytes treated with sodium nitrite was not significantly different than that in untreated myocytes at high PO2, but it was significantly lower than controls at low PO2. O2 consumption of sea raven myocytes treated with the mitochondrial uncoupler CCCP was not significantly different from that of control myocytes at high PO2, but it was significantly greater than untreated controls at low PO2. In ocean pout preparations, O2 consumption by nitrite-treated myocytes was significantly higher than that of untreated myocytes at high PO2, but it was not different from that of controls at low PO2. CCCP-treated ocean pout myocytes had a significantly higher oxygen consumption than that of untreated myocytes at high PO2, but oxygen consumption was not different from that of controls at low PO2. The CCCP-activated O2 consumption at low PO2 was myoglobin-dependent in that CCCP alone resulted in a threefold increase in sea raven cells over controls but had no impact on sea raven cells in the presence of nitrite or ocean pout cells treated with CCCP alone. This study further supports the contention that myoglobin only plays an important role in oxygen metabolism at low extracellular PO2's.
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Affiliation(s)
- N J Legate
- Department of Biology, Mount Allison University, Sackville, Canada
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Bushnell PG, Brill RW. Oxygen transport and cardiovascular responses in skipjack tuna (Katsuwonus pelamis) and yellowfin tuna (Thunnus albacares) exposed to acute hypoxia. J Comp Physiol B 1992; 162:131-43. [PMID: 1592908 DOI: 10.1007/bf00398338] [Citation(s) in RCA: 90] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Responses to acute hypoxia were measured in skipjack tuna (Katsuwonus pelamis) and yellowfin tuna (Thunnus albacares) (approximately 1-3 kg body weight). Fish were prevented from making swimming movements by a spinal injection of lidocaine and were placed in front of a seawater delivery pipe to provide ram ventilation of the gills. Fish could set their own ventilation volumes by adjusting mouth gape. Heart rate, dorsal and ventral aortic blood pressures, and cardiac output were continuously monitored during normoxia (inhalant water (PO2 greater than 150 mmHg) and three levels of hypoxia (inhalant water PO2 approximately 130, 90, and 50 mmHg). Water and blood samples were taken for oxygen measurements in fluids afferent and efferent to the gills. From these data, various measures of the effectiveness of oxygen transfer, and branchial and systemic vascular resistance were calculated. Despite high ventilation volumes (4-7 l.min-1.kg-1), tunas extract approximately 50% of the oxygen from the inhalant water, in part because high cardiac outputs (115-132 ml.min-1.kg-1) result in ventilation/perfusion conductance ratios (0.75-1.1) close to the theoretically ideal value of 1.0. Therefore, tunas have oxygen transfer factors (ml O2.min-1.mmHg-1.kg-1) that are 10-50 times greater than those of other fishes. The efficiency of oxygen transfer from water in tunas (approximately 65%) matches that measured in teleosts with ventilation volumes an order of magnitude lower. The high oxygen transfer factors of tunas are made possible, in part, by a large gill surface area; however, this appears to carry a considerable osmoregulatory cost as the metabolic rate of gills may account for up 70% of the total metabolism in spinally blocked (i.e., non-swimming) fish. During hypoxia, skipjack and yellowfin tunas show a decrease in heart rate and increase in ventilation volume, as do other teleosts. However, in tunas hypoxic bradycardia is not accompanied by equivalent increases in stroke volume, and cardiac output falls as HR decreases. In both tuna species, oxygen consumption eventually must be maintained by drawing on substantial venous oxygen reserves. This occurs at a higher inhalant water PO2 (between 130 and 90 mmHg) in skipjack tuna than in yellowfin tuna (between 90 and 50 mmHg). The need to draw on venous oxygen reserves would make it difficult to meet the oxygen demand of increasing swimming speed, which is a common response to hypoxia in both species.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- P G Bushnell
- John A. Burns School of Medicine, Department of Physiology, University of Hawaii, Honolulu 96822
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Cardiac Energy Metabolism. ACTA ACUST UNITED AC 1992. [DOI: 10.1016/s1546-5098(08)60335-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2023]
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Driedzic WR, Sidell BD, Stewart JM, Johnston IA. Maximal Activities of Enzymes of Energy Metabolism in Cephalopod Systemic and Branchial Hearts. ACTA ACUST UNITED AC 1990. [DOI: 10.1086/physzool.63.3.30156232] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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21
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Fitch NA. Lactate dehydrogenase isozymes in the trunk and cardiac muscles of an antarctic teleost fish,Notothenia neglecta Nybelin. FISH PHYSIOLOGY AND BIOCHEMISTRY 1989; 6:187-195. [PMID: 24227074 DOI: 10.1007/bf01874775] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The distribution and kinetics of lactate dehydrogenase (LDH) isozymes in the red and white trunk muscles, and cardiac muscle of an antarctic teleost fish (Notothenia neglecta Nybelin) have been studied. Pyruvate inhibition of LDH in all three muscle types is very low, being less than 50% even at a concentration of 60mM pyruvate. Activity versus pyruvate concentration profiles are not significantly different for LDH in all three muscle types. The Michaelis constant (Km) for pyruvate was not significantly different for all three LDH's. Raising the assay temperature caused an increase in Km of similar form in all three muscle types, while Km was lowest at the lowest assay temperature (-1°C). When samples were run on a polyacrylamide gel, the bands stained specifically for LDH activity appeared at identical positions as those of the H2M2 band of the standards.It would appear therefore that the LDH isozyme found in the red and white trunk muscle ofN. neglecta is identical to that in cardiac muscle. This fact is discussed in relation to the physiological ecology of antaretic fishes, and the metabolic constraints imposed by their habitat, including their apparent low capacity for utilising glycolytic fuels.
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Affiliation(s)
- N A Fitch
- Department of Physiology and Pharmacology, Gatty Marine Laboratory, KY168LB, St. Andrews, Scotland
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Abstract
Myoglobins from rat, coho salmon (Oncorhynchus kisutch), buffalo sculpin (Enophrys bison) hearts, and yellowfin tuna (Thunnus albacares) red skeletal muscle were partially purified and their O2 binding affinities determined. Commercially prepared sperm whale myoglobin was employed as an internal standard. Tested at 20 degrees C, myoglobins from salmon and sculpin bound O2 with lower affinity than myoglobins from the rat or sperm whale. Oxygen binding studies at 12 degrees C and 37 degrees C suggest that this difference is adaptive, permitting myoglobins from cold-adapted fish to function at physiologically relevant temperatures. Taken together, purification and O2 binding data obtained in this study reveal a previously unrecognized diversity of myoglobin structure and function.
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Affiliation(s)
- J W Nichols
- Oregon State University, Hatfield Marine Science Center, Newport 97365
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Fitch NA. Lactate dehydrogenases in Antarctic and temperate fish species. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. B, COMPARATIVE BIOCHEMISTRY 1988; 91:671-6. [PMID: 3224505 DOI: 10.1016/0305-0491(88)90190-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
1. The kinetics of lactate dehydrogenase (both forward and back reaction) in cardiac and skeletal muscle of an Antarctic teleost have been compared with a temperate teleost of comparable morphology and ecology. 2. In both species the forward reaction (pyruvate to lactate) is maximally activated at 2.5-4 mM pyruvate and inhibited above this level. 3. The Michaelis constant (Km) for pyruvate is not significantly different between muscle types or between species when measured at their normal environmental temperature. 4. Km for pyruvate varies with temperature in a positive direction. 5. The back reaction (lactate to pyruvate) is maximally activated by 12-16 mM lactate but only in skeletal muscle of the antarctic species is there inhibition above this level. 6. The Km for lactate is significantly (P less than 0.05) lower in the Antarctic fish cardiac muscle. 7. While the two species are morphologically and ecologically similar, differences at the biochemical level are discussed with respect to environmental temperature range and conservation of enzymic characteristics.
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Affiliation(s)
- N A Fitch
- Department of Physiology and Pharmacology, Gatty Marine Laboratory, St. Andrews, UK
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Wittenberg BA, Wittenberg JB. Myoglobin-mediated oxygen delivery to mitochondria of isolated cardiac myocytes. Proc Natl Acad Sci U S A 1987; 84:7503-7. [PMID: 3118370 PMCID: PMC299324 DOI: 10.1073/pnas.84.21.7503] [Citation(s) in RCA: 94] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Myoglobin-mediated oxygen delivery to intracellular mitochondria is demonstrated in cardiac myocytes isolated from the hearts of mature rats. Myocytes are held at high ambient oxygen pressure, 40-340 torr (5-45 kPa); sarcoplasmic myoglobin is fully oxygenated. In this condition oxygen availability does not limit respiratory rate; myoglobin-facilitated diffusion contributes no additional oxygen flux and, since oxygen consumption is measured in steady states, the storage function of myoglobin vanishes. Carbon monoxide, introduced stepwise, displaces oxygen from intracellular oxymyoglobin without altering the optical spectrum of the largely oxidized intracellular mitochondria. A large part, about one-third, of the steady-state oxygen uptake is abolished by carbon monoxide blockade of myoglobin oxygenation. The myoglobin-dependent component of the oxygen uptake decreases linearly with decreasing fraction of intracellular oxymyoglobin, with a slope near unity. Studies using inhibitors of mitochondrial electron transport indicate that myoglobin-delivered oxygen uptake depends on electron flow through the mitochondrial electron transport chain. We conclude that cardiac mitochondria accept two additive simultaneous flows of oxygen: a flow of dissolved oxygen to cytochrome oxidase and a flow of myoglobin-bound oxygen to a mitochondrial terminus. Myoglobin-mediated oxygen delivery supports ATP generation by heart cells at physiological ambient oxygen pressure.
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Affiliation(s)
- B A Wittenberg
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, NY 10461
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Sidell BD, Driedzic WR, Stowe DB, Johnston IA. Biochemical Correlations of Power Development and Metabolic Fuel Preferenda in Fish Hearts. ACTA ACUST UNITED AC 1987. [DOI: 10.1086/physzool.60.2.30158646] [Citation(s) in RCA: 136] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Johnston IA, Harrison P. Morphometrics and ultrastructure of myocardial tissue in Notothenioid fishes. FISH PHYSIOLOGY AND BIOCHEMISTRY 1987; 3:1-6. [PMID: 24233247 DOI: 10.1007/bf02183988] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Antarctic fish of the family Channichthyidae (Icefishes) lack the respiratory pigments haemoglobin and myoglobin. The morphometrics and ultrastructure of the ventricular myocardium of a benthic icefish,Chaenocephalus aceratus has been compared with that of a red-blooded Notothenioid fish,Notothenia neglecta, of similar habit.The mass of ventricular muscle as a percentage of bodyweight is 3 times greater in adultC. aceratus (0.32%) thanN. neglecta (0.11%). Myoglobin concentration in the ventricle ofN. neglecta, 20 nmoles/g, is comparable to that of temperate teleosts with similar activity patterns. The volume and surface densities of mitochondria are 41.5% and 0.32 μm(-1) for Icefish and 25% and 0.15 μm(-1) forN. neglecta, Cytochrome oxidase activities are similar in the two tissues whilst the volume density of myofibrils is higher forN. neglecta (47%) thanC. aceratus (29.9%).The proliferation of mitochondria in the myocardium of Icefish will reduce the diffusion path-length for oxygen between ventricular lumen and the outer mitochondrial membrane and may compensate for the absence of myoglobin.
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Affiliation(s)
- I A Johnston
- British Antarctic Survey, Natural Environment Research Council, Madingley Road, High Cross, Cambridge, CB3 OET, England
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Egginton S. Metamorphosis of the American eel, Anguilla rostrata LeSeur: I. Changes in metabolism of skeletal muscle. THE JOURNAL OF EXPERIMENTAL ZOOLOGY 1986; 237:173-84. [PMID: 3950563 DOI: 10.1002/jez.1402370204] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Unequivocal demarcation between immature, nonmigratory yellow eels and migratory silver eels of greater sexual maturity is possible by measuring eye diameter and retinal capillary length, which undergo a 1.5- and 2.3-fold increase during metamorphosis, respectively. Anatomical arrangement of trunk musculature is similar in the two groups except for an increased depth of slow muscle in silver eel. Histochemical analysis reveals a progressive increase in numbers of "displaced" fast fibres within slow muscle of the lateral line triangle in maturing eels, although these are unlikely to affect recruitment pattern of muscle fibre types. Previous studies have suggested greater involvement of fast muscle in locomotion of migratory eels. In contrast, estimates of enzyme activity in fast muscle suggest an inadequate aerobic capacity to fuel sustained activity. Myoglobin content is extremely low, around 0.4 nM g wet wt-1. Prolonged anaerobic metabolism is also discounted as a migratory strategy. Increased energy provision for migration is apparently derived from increased capacity for both aerobic carbohydrate metabolism and mitochondrial fatty acid oxidation within slow muscle of silver eels. Activity of hexokinase (HK) shows a 1.6-fold increase (to 0.51 microM g wet wt-1) and carnitine palmitoyltransferase (CPT) a 3.1-fold increase (to 0.22 microM g wet wt-1 min-1), suggesting a maximal flux through these pathways of 18 and 14 ATP equivalents, respectively. However, the fatty acyl transferase system of skeletal muscle mitochondria displays up to threefold greater activity with palmitoleoyl CoA (C16:1) as substrate than with the usual palmitoyl CoA (C16:0). Slow muscle of silver eel is therefore capable of deriving aerobic energy from free fatty acids and carbohydrate in the ratio 2.3:1. Differences in aerobic enzyme activities are not paralleled by myoglobin content of slow muscle, being 15 and 16 nM g wet wt-1 for yellow and silver eel, respectively. Structural reorganization of muscle fibres during metamorphosis, however, results in a twofold elevation of cytoplasmic myoglobin concentration in silver eel. It would appear that dramatic differences in metabolic capacity between life history stages of eel is required to overcome locomotory inefficiency of yellow eels and to "preadapt" silver eels for migratory activity. This increased locomotory capacity may be amplified by a subsequent training response.
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Driedzic WR, Gesser H. Ca2+ protection from the negative inotropic effect of contraction frequency on teleost hearts. J Comp Physiol B 1985. [DOI: 10.1007/bf00692936] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Sidell BD, Driedzic WR. Relationship Between Cardiac Energy Metabolism and Cardiac Work Demand in Fishes. PROCEEDINGS IN LIFE SCIENCES 1985. [DOI: 10.1007/978-3-642-70610-3_31] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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Relationship between exogenous fuel availability and performance by teleost and elasmobranch hearts. J Comp Physiol B 1984. [DOI: 10.1007/bf00684413] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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