Showing papers on "Myoglobin published in 2004"
TL;DR: The majority of modern organisms, including many prokaryotes, are aerobes; that is, they use molecular oxygen as the terminal electron acceptor for energy generation, and the four-electron, four-proton reduction of O2 to H2O (reaction 1) dominates.
Abstract: The majority of modern organisms, including many prokaryotes, are aerobes;1 that is, they use molecular oxygen as the terminal electron acceptor for energy generation. Although nearly every redox gradient in nature appears to be utilized by one organism or another,2-4 aerobic metabolism predominates, in large part due to the highly exergonic nature of the four-electron, four-proton (4e/4H+) reduction of O2 to H2O (reaction 1). A multicellular aerobe requires an
599 citations
TL;DR: These recent findings, coupled with additional emerging technologies and the discovery of other tissue globins, provide a framework for addressing new questions about myoglobin and readdressing old ones.
Abstract: Myoglobin is a cytoplasmic hemoprotein, expressed solely in cardiac myocytes and oxidative skeletal muscle fibers, that reversibly binds O2 by its heme residue, a porphyrin ring:iron ion complex. Since the initial discovery of its structure over 40 years ago, wide-ranging work by many investigators has added importantly to our understanding of its function and regulation. Functionally, myoglobin is well accepted as an O2-storage protein in muscle, capable of releasing O2 during periods of hypoxia or anoxia. Myoglobin is also thought to buffer intracellular O2 concentration when muscle activity increases and to facilitate intracellular O2 diffusion by providing a parallel path that augments simple diffusion of dissolved O2. The use of gene targeting and other molecular biological techniques has revealed important new insights into the developmental and environmental regulation of myoglobin and provided additional functions for this hemoprotein such as scavenging nitric oxide and reactive O2 species. These recent findings, coupled with additional emerging technologies and the discovery of other tissue globins, provide a framework for addressing new questions about myoglobin and readdressing old ones.
376 citations
TL;DR: A new transition metal-based reaction has been developed for the selective modification of tryptophan residues on protein substrates and it was demonstrated that myoblobin concentrations as low as 10 muM still led to appreciable levels of modification.
Abstract: A new transition metal-based reaction has been developed for the selective modification of tryptophan residues on protein substrates. After activation of vinyl-substituted diazo compounds by Rh2(OAc)4, the resulting metallocarbenoid intermediates were found to modify indoles in aqueous media despite competing reactions with water. Both N- and 2-substituted indole products were observed in the reaction. Following initial small-molecule studies, the reaction was performed on two protein substrates. Both myoglobin and subtilisin Carlsberg were modified readily in aqueous solution, and the tryptophan selectivity of the reactions was confirmed through MS analyses of trypsin digest fragments. It was also demonstrated that myoblobin concentrations as low as 10 muM still led to appreciable levels of modification. Reconstitution experiments confirmed that myoglobin retained its ability to bind heme following modification.
238 citations
TL;DR: Human cytoglobin displays a large apolar protein matrix cavity, next to the heme, not related to the myoglobin cavities recognized as temporary ligand docking stations, which may provide a heme ligand diffusion pathway.
155 citations
TL;DR: This review focuses on the peroxide-induced formation of radicals, their assignment to specific protein residues, and the pseudoperoxidase and prooxidant activities of the heme proteins.
Abstract: Recent research has shown that myoglobin and hemoglobin play important roles in the pathology of certain disease states, such as renal dysfunction following rhabdomyolysis and vasospasm following subarachnoid hemorrhages. These pathologies are linked to the interaction of peroxides with heme proteins to initiate oxidative reactions, including generation of powerful vasoactive molecules (the isoprostanes) from free and membrane- bound lipids. This review focuses on the peroxide-induced formation of radicals, their assignment to specific protein residues, and the pseudoperoxidase and prooxidant activities of the heme proteins. The discovery of heme to protein cross-linked forms of myoglobin and hemoglobin in vivo, definitive markers of the participation of these heme proteins in oxidative reactions, and the recent results from heme oxygenase knockout/knockin animal model studies, indicate that higher oxidation states (ferryl) of heme proteins and their associated radicals play a major role in the mechanisms of pathology.
153 citations
TL;DR: Polyclonal antibodies have now been developed that bind to protein adducts of the nitrone spin trap 5,5-dimethyl-1-pyrroline N-oxide that demonstrated that myoglobin forms the predominant detectable protein radical in rat heart supernatant, and hemoglobin radicals form inside red blood cells.
148 citations
TL;DR: The aim of this study was to investigate the effects of physical activity, in particular muscle damage and oxidative stress, during and after a half-marathon race and the subsequent recovery period and to measure whether oxidative stress attributable to reoxygenation may be a relevant factor in cellular damage.
Abstract: Physical exercise leads to temporary ischemia in muscles, followed by increased oxygen supply during recovery as a result of reperfusion. It is thought that the sudden influx of oxygen causes a calcium overload in cells, leading to an influx of inflammatory cells into reperfused tissue. This leads to the generation of reactive oxygen radicals and subsequent oxidative damage to DNA, proteins, and lipids. For example, increased oxidant production in the mitochondria of muscles during acute exercise, followed by reoxygenation, was shown to cause cellular damage (1). In addition, exercise may cause transient muscle damage, characterized by muscle soreness, muscle fiber disarrangement, muscle protein release into plasma, an acute immune response, and decreased muscle performance (2).
Regional ATP depletion during reperfusion, disruptions in calcium homeostasis, and the presence of oxygen free radicals have all been implicated in the etiology of muscle fiber damage and necrosis. Furthermore, postexercise lymphocytopenia (2) is well documented and attributed to the exit of lymphocytes from the vascular compartment (3). Other studies have reported exercise-induced DNA damage in leukocytes and raised the question of a possible link to apoptosis (3). This effect is thought to be caused by reactive oxygen species, which are released from peripheral monocytes.
The aim of this study was to investigate the effects of physical activity, in particular muscle damage and oxidative stress, during and after a half-marathon race and the subsequent recovery period; we also wanted to measure whether oxidative stress attributable to reoxygenation may be a relevant factor in cellular damage. Cell-free plasma DNA concentrations were used as a sensitive tool for quantification of cellular damage and compared with the conventional measurements of myoglobin and uric acid in blood samples.
In this study, blood samples from half-marathon runners were taken before the race, immediately after the race, and 2 h …
145 citations
TL;DR: A sensor to detect markers of cardiac muscle cell death at less than 3ngml(-1) and in less than 10min has been achieved and an in vivo sensor for the early detection of the onset of myocardial infarction (MI) will greatly enhance the patient care.
137 citations
TL;DR: Density functional theory (DFT), transition-state theory (TST), and hybrid DFT/molecular mechanics (QM/MM) calculations are reported on the carbon monoxide reaction, suggesting a highly non-adiabatic nature to the reaction.
Abstract: The reaction of small ligands within the distal pocket of haem proteins such as myoglobin, to form ligated, low-spin iron complexes is an archetypal spin-forbidden process in bioinorganic chemistry, because the initial, “deoxy” iron complex has a high-spin ground state. Density functional theory (DFT), transition-state theory (TST), and hybrid DFT/molecular mechanics (QM/MM) calculations are reported on the carbon monoxide reaction. Using DFT data for a model compound, TST rate calculations at room temperature are carried out which give fair agreement with experiment, and suggest a highly non-adiabatic nature to the reaction. QM/MM calculations on the whole protein are reported, which are in qualitative agreement with the gas-phase model results, but suggest that protein matrix effects on the reaction rate may be important.
132 citations
TL;DR: The complexes of horse myoglobin with the anionic surfactant sodium dodecyl sulfate (SDS), and with the cationic surfactants cetyltrimethylammonium chloride (CTAC) and DeTAB, have been studied by a combination of surface tension measurements and optical spectroscopy, including heme absorption and aromatic amino acid fluorescence.
123 citations
TL;DR: The preparation and characterization of a new trypsin-based bioreactor is here described for on-line protein digestion and peptide analysis and the influence of various parameters (flow rate, temperature, buffer pH and molarity, etc.) on enzymatic activity was investigated and the mostly significant factor was found to be the flow rate.
TL;DR: The results suggest that thiolate ligation does not significantly alter the catalytic reactivity, but the dramatic difference in product distribution may suggest an important role for protein stability in the selectivity of biocatalysts.
Abstract: Previous investigations of nitrite and nitric oxide reduction by myoglobin in surfactant film modified electrodes characterized several distinct steps in the denitrification pathway, including isolation of a nitroxyl adduct similar to that proposed in the P450nor catalytic cycle. To investigate the effect of the axial ligand on these biomimetic reductions, we report here a comparison of the electrocatalytic activity of myoglobin (Mb) with a thermophilic cytochrome P450 CYP119. Electrocatalytic nitrite reduction by CYP119 is very similar to that by Mb: two catalytic waves at analogous potentials are observed, the first corresponding to the reduction of nitric oxide, the second to the production of ammonia. CYP119 is a much more selective catalyst, giving almost exclusively ammonia during the initial half-hour of reductive electrolysis of nitrite. More careful investigations of specific steps in the catalytic cycle show comparable rates of nitrite dehydration and almost identical potentials and lifetimes f...
TL;DR: Using both classical and mixed quantum-classical molecular dynamics calculations, the rapid motion of CO away from the distal heme pocket to other regions of the protein is observed, in agreement with recent experimental results.
Abstract: Molecular dynamics simulations of the events after the photodissociation of CO in the myoglobin mutant L29F in which leucine is replaced by phenylalanine are reported. Using both classical and mixed quantum-classical molecular dynamics calculations, we observed the rapid motion of CO away from the distal heme pocket to other regions of the protein, in agreement with recent experimental results. The experimentally observed and calculated infrared spectra of CO after dissociation are also in good agreement. We compared the results with data from simulations of WT myoglobin. As the time resolution of experimental techniques is increased, theoretical methods and models can be validated at the atomic scale by direct comparison with experiment.
TL;DR: Results show that myoglobin concentration has a moderate heritability and could be used in a selection program to make pork loins darker in color.
Abstract: An evaluation of porcine longissimus myoglobin concentration was conducted to determine breed and gender differences for myoglobin content, estimate genetic parameters for myoglobin concentration, and determine the relationship between myoglobin content and objective measures of muscle color. Data from centrally tested (n = 255), purebred Yorkshire (42), Duroc (61), Hampshire (17), Chester White (28), Berkshire (67), Poland China (28), and Landrace (12) barrows and gilts from the 1999 National Barrow Show Sire Progeny Test were used. Ultimate pH and Hunter L were measured on the 10th-rib face 24 h postmortem. A section of bone-in loin containing the 10th rib was taken to the Iowa State University Meats Laboratory. At 48 h postmortem, Hunter L, CIE L*, a*, and b*, Japanese color score, and water-holding capacity were measured on the face of the 10th-rib loin chop. A slice from the 10th-rib loin section was evaluated for percentage of i.m. fat. The resulting loin chop was used for the determination of soluble myoglobin concentration (mg/g, wet basis). Chester White, Hampshire, and Duroc pigs had the highest (P < 0.05) myoglobin concentration (0.92, 0.95, and 0.85 mg/g, respectively), whereas Landrace had the lowest (0.62 mg/g; P < 0.05). No gender differences were detected for myoglobin concentration. The heritability estimate for soluble myoglobin concentration was 0.27. Residual correlations between soluble myoglobin and CIE L*, a*, b*, Hunter L (24 h), Hunter L (48 h), and Japanese color score were -0.17, 0.23, -0.15, -0.16, -0.13, and 0.13, respectively. These correlations are low but in the desired direction. The residual correlation between soluble myoglobin and intramuscular fat percent was 0.18. Results show that myoglobin concentration has a moderate heritability and could be used in a selection program to make pork loins darker in color.
TL;DR: The extended relaxation of the globin moiety directly observed by Laue crystallography reflects re-equilibration among conformational substates known to play an essential role in controlling protein function.
TL;DR: Comparisons of reduction kinetics of hexacoordinate hemoglobins, including human neuroglobin and cytoglobin, and those from Synechocystis and rice, are compared to myoglobin, soybean leghemobic proteins, and several relevant mutant proteins show differences in the reorganization energy for reduction.
Abstract: Hexacoordinate hemoglobins are a class of proteins that exhibit reversible bis-histidyl coordination of the heme iron while retaining the ability to bind exogenous ligands. One hypothesis for their physiological function is that they scavenge nitric oxide, a reaction that oxidizes the protein and requires reduction of the heme iron to continue. Reduction kinetics of hexacoordinate hemoglobins, including human neuroglobin and cytoglobin, and those from Synechocystis and rice, are compared to myoglobin, soybean leghemoglobin, and several relevant mutant proteins. In all cases, bis-histidyl coordination greatly increases the rate of reduction by sodium dithionite when compared to pentacoordinate hemoglobins. In myoglobin and leghemoglobin, reduction is limited by the rate constant for electron transfer, whereas in the hexacoordinate hemoglobins reduction is limited only by bimolecular binding of the reductant. These results can be explained by differences in the reorganization energy for reduction between he...
TL;DR: The high O2 affinity and the unique characteristics of the myoglobin with the iron porphycene indicate that reconstitution with a synthesized heme is a useful method not only to understand the physiological function of myoglobin but also to create a tailor-made function on the protein.
Abstract: Sperm whale myoglobin, an oxygen storage hemoprotein, was successfully reconstituted with the iron porphycene having two propionates, 2,7-diethyl-3,6,12,17-tetramethyl-13,16-bis(carboxyethyl)porphycenatoiron. The physicochemical properties and ligand bindings of the reconstituted myoglobin were investigated. The ferric reconstituted myoglobin shows the remarkable stability against acid denaturation and only a low-spin characteristic in its EPR spectrum. The Fe(III)/Fe(II) redox potential (−190 mV vs NHE) determined by the spectroelectrochemical measurements was much lower than that of the wild-type. These results can be attributed to the strong coordination of His93 to the porphycene iron, which is induced by the nature of the porphycene ring symmetry. The O2 affinity of the ferrous reconstituted myoglobin is 2600-fold higher than that of the wild-type, mainly due to the decrease in the O2 dissociation rate, whereas the CO affinity is not so significantly enhanced. As a result, the O2 affinity of the reco...
TL;DR: The present results indicate that the combination of a modified-heme reconstitution and an amino acid mutation should offer interesting perspectives toward developing a useful biomolecule catalyst from a hemoprotein.
Abstract: To modulate the physiological function of a hemoprotein, most approaches have been demonstrated by site-directed mutagenesis. Replacement of the native heme with an artificial prosthetic group is another way to modify a hemoprotein. However, an alternate method, mutation or heme reconstitution, does not always demonstrate sufficient improvement compared with the native heme enzyme. In the present study, to convert a simple oxygen storage hemoprotein, myoglobin, into an active peroxidase, we applied both methods at the same time. The native heme of myoglobin was replaced with a chemically modified heme 2 having two aromatic rings at the heme-propionate termini. The constructed myoglobins were examined for 2-methoxyphenol (guaiacol) oxidation in the presence of H2O2. Compared with native myoglobin, rMb(H64D·2) showed a 430-fold higher kcat/Km value, which is significantly higher than that of cytochrome c peroxidase and only 3-fold less than that of horseradish peroxidase. In addition, myoglobin-catalyzed de...
TL;DR: The protein levels of myoglobin, myosin light chain and HSP20 were higher in red muscle, whereas HSP27 was higher in white muscle, and positive correlations between protein content and their mRNA levels were observed in white and red muscle.
Abstract: Skeletal muscle is an heterogeneous tissue with various biochemical and physical properties of several fiber types. In this study, we carried out the comparative study of protein expression patterns in white and red muscles using two-dimensional gel electrophoresis (2-DE). From more than 500 protein spots detected on each 2-DE gel, we screened five proteins that were differentially expressed between white and red muscles. Using peptide mass fingerprint and tandem mass spectrometry analysis these proteins were identified as myoglobin, two slow-twitch isoforms of myosin light chain and two small heat shock proteins (HSP20 and HSP27). The protein levels of myoglobin, myosin light chain and HSP20 were higher in red muscle, whereas HSP27 was higher in white muscle. In addition, genes of the identified proteins were cloned and their mRNAs were examined. Positive correlations between protein content and their mRNA levels were observed in white and red muscle. These results may provide us with valuable information to understand the different expression profiling between white and red muscle at the protein level.
TL;DR: The directional and enhanced directional fluorescence emission enables detection of myoglobin over a wide range of concentrations from subnormal to the elevated level of this cardiac marker and allows for significant background suppression in the myoglobin immunoassay.
Abstract: We described an immunoassay for the cardiac marker myoglobin on a thin silver mirror surface using surface plasmon-coupled emission (SPCE). SPCE occurs for fluorophores in proximity (within ∼200 nm) of a thin metal film (in our case, silver) and results in a highly directional radiation through a glass substrate at a well-defined angle from the normal axis. We used the effect of SPCE to develop a myoglobin immunoassay on the silver mirror surface deposited on a glass substrate. Binding of the labeled anti-myoglobin antibodies led to the enhanced fluorescence emission at a specific angle of 72°. The directional and enhanced directional fluorescence emission enables detection of myoglobin over a wide range of concentrations from subnormal to the elevated level of this cardiac marker. Utilizing SPCE allowed us also to demonstrate significant background suppression (from serum or whole blood) in the myoglobin immunoassay. We expect SPCE to become a powerful technique for performing immunoassays for many bioma...
TL;DR: The dynamics of the ferric CN complexes of the heme proteins Myoglobin and Hemoglobin I from the clam Lucina pectinata upon Soret band excitation is monitored using infrared and broad band visible pump-probe spectroscopy for transient response in the UV-vis spectral region.
TL;DR: NMR data reveal that [Mb] is increased in human muscle with a high oxidative capacity and a highly responsive vasculature, and the rate at which Mb resaturates is well correlated with the rephosphorylation rate of Cr, each of which support a teleological role for Mb in O(2) transport within highly oxidative human skeletal muscle.
Abstract: In human muscle the role of myoglobin (Mb) and its relationship to factors such as muscle perfusion and metabolic capacity are not well understood. We utilized nuclear magnetic resonance (NMR) to s...
TL;DR: It is shown that VEGF upregulates myoglobin in ischemic muscle both in vitro and in vivo, which implies an improved muscle oxygenation, which may, at least partly, explain observed clinical improvements in V EGF-treated patients, in the absence of improved vascularization.
Abstract: Therapeutic angiogenesis using vascular endothelial growth factor (VEGF) is considered a promising new therapy for patients with arterial obstructive disease. Clinical improvements observed consist of improved muscle function and regression of rest pain or angina. However, direct evidence for improved vascularization, as evaluated by angiography, is weak. In this study, we report an angiogenesis-independent effect of VEGF on ischemic skeletal muscle, ie, upregulation of myoglobin after VEGF treatment. Mice received intramuscular injection with adenoviral VEGF-A or either adenoviral LacZ or PBS as control, followed by surgical induction of acute hindlimb ischemia at day 3. At day 6, capillary density was increased in calf muscle of Ad. VEGF-treated versus control mice (P<0.01). However, angiographic score of collateral arteries was unchanged between Ad. VEGF-treated and control mice. More interestingly, an increase in myoglobin was observed in Ad. VEGF-treated mice. Active myoglobin was 1.5-fold increased in calf muscle of Ad. VEGF-treated mice (P≤0.01). In addition, the number of myoglobin-stained myofibers was 2.6-fold increased in Ad. VEGF-treated mice (P=0.001). Furthermore, in ischemic muscle of 15 limb amputation patients, VEGF and myoglobin were coexpressed. Finally, in cultured C2C12 myotubes treated with rhVEGF, myoglobin mRNA was 2.8-fold raised as compared with PBS-treated cells (P=0.02). This effect could be blocked with the VEGF receptor tyrosine kinase inhibitor SU5416. In conclusion, we show that VEGF upregulates myoglobin in ischemic muscle both in vitro and in vivo. Increased myoglobin expression in VEGF-treated muscle implies an improved muscle oxygenation, which may, at least partly, explain observed clinical improvements in VEGF-treated patients, in the absence of improved vascularization. Chemicals / CAS: semaxanib, 186610-95-7; vasculotropin A, 489395-96-2; vasculotropin, 127464-60-2; Myoglobin; RNA, Messenger; Vascular Endothelial Growth Factor A
TL;DR: The mechanism for the reaction between nitric oxide (NO) and O2 bound to the heme iron of myoglobin (Mb), including the following isomerization to nitrate, has been investigated using hybrid density functional theory (B3LYP).
Abstract: The mechanism for the reaction between nitric oxide (NO) and O(2) bound to the heme iron of myoglobin (Mb), including the following isomerization to nitrate, has been investigated using hybrid density functional theory (B3LYP). Myoglobin working as a NO scavenger could be of importance, since NO reversibly inhibits the terminal enzyme in the respiration chain, cytochrome c oxidase. The concentration of NO in the cell will thus affect the respiration and thereby the synthesis of ATP. The calculations show that the reaction between NO and the heme-bound O(2) gives a peroxynitrite intermediate whose O-O bond undergoes a homolytic cleavage, forming a NO(2) radical and myoglobin in the oxo-ferryl state. The NO(2) radical then recombines with the oxo-ferryl, forming heme-bound nitrate. Nine different models have been used in the present study to examine the effect on the reaction both by the presence and the protonation state of the distal His64, and by the surroundings of the proximal His93. The barriers going from the oxy-Mb and nitric oxide reactant to the peroxynitrite intermediate and further to the oxo-ferryl and NO(2) radical are around 10 and 7 kcal/mol, respectively. Forming the product, nitrate bound to the heme iron has a barrier of less than approximately 7 kcal/mol. The overall reaction going from a free nitric oxide and oxy-Mb to the heme bound nitrate is exergonic by more than 30 kcal/mol.
TL;DR: Despite the conserved globin fold, the cavity found in CYGB* is structured differently from those recognized to play a functional role in myoglobin, neuroglobin, truncated hemoglobins, and Cerebratulus lacteus mini-hemoglobin.
TL;DR: The data suggest that MW‐EMF could have also biochemical and, consequently, biological effects on eukaryotic cells that are still under investigation, and changes in the structural fluctuation caused by MW perturbation can affect differently the aggregation process that occurs competitively during the protein folding, so representing a potential risk for protein “misfolding.
Abstract: Non-thermal effects induced by exposure to microwave electromagnetic field (MW-EMF) at 1.95 MHz, a frequency used in mobile communication, have been observed on the refolding kinetics of the heme binding site in an intracellular protein: tuna myoglobin, starting from acidic conditions. We have selected myoglobin because it can be considered a good model to study protein interactions with MW-EMF for its well-known high-resolution crystallographic structure. Myoglobin solutions at pH 3.0 were subjected to 3 h exposure to microwave field (with a specific absorption rate of 51 +/- 1 mW/g); the heme site refolding has been followed by measuring the molecular absorption in the Soret spectral region and the data were fitted to a bi-exponential model. The kinetics of exposed samples appear to be slowered by MW-EMF action. Moreover, the tryptophanyl lifetime distribution of the exposed protein, as deduced by the analysis of the fluorescence emission decay from its single tryptophan, appears sharper if compared to non-exposed protein samples. This observation suggests that the presence of MW-EMF could affect the propensity of protein molecules to populate specific conformational substates among which myoglobin molecules fluctuate at acidic pH. Changes in the structural fluctuation caused by MW perturbation can affect differently the aggregation process that occurs competitively during the protein folding, so representing a potential risk for protein "misfolding." These data suggest that MW-EMF could have also biochemical and, consequently, biological effects on eukaryotic cells that are still under investigation.
TL;DR: In this article, a combined experimental and theoretical investigation of met-myoglobin (Fe III ) with H 2 O 2 gives rise to ferryl myoglobin, which is closely related to compound II in peroxidases.
TL;DR: In this article, the myoglobin/clay/glassy carbon electrode (Mb/Clay/GCE) showed a quasi-reversible, electrochemical redox behavior of the adsorbed protein with a formal potential of −0.380±0.010
Abstract: Sodium montmorillonite was prepared via a colloidal chemical approach and deposited onto glassy carbon electrodes (GCE). Myoglobin was immobilized on the clay membrane modified electrode by spontaneous adsorption. Characterization of the myoglobin/clay/glassy carbon electrode (Mb/clay/GCE) showed a quasi-reversible, electrochemical redox behavior of the adsorbed protein with a formal potential of −0.380±0.010 V (vs. Ag/AgCl). The heterogeneous electron transfer rate constant was found to be strongly influenced by the buffer concentration. The Mb/clay/GCE was stable for several days in solution. The interaction of the immobilized Mb with nitric oxide (NO) is characterized by coordination chemistry. The reaction was found to be reversible and could be applied for NO detection in the nanomolar concentration range by a voltammetric analysis. In addition a mixed protein electrode with co-immmobilized myoglobin (Mb) and cytochrome c (Cyt.c) was developed. By choice of the electrode potential both proteins can be addressed independently.
TL;DR: The findings suggest that L-CA concentration in muscle is related to oxygen metabolism and to myofiber types.