Plasma Creatine Kinase Research Articles

CoaTx-II, a new dimeric Lys49 phospholipase A2 from Crotalus oreganus abyssus snake venom with bactericidal potential: Insights into its structure and biological roles

Snake venoms are rich and intriguing sources of biologically-active molecules that act on target cells, modulating a diversity of physiological functions and presenting promising pharmacological applications. Lys49 phospholipase A2 is one of the multifunctional proteins present in these complex secretions and, although catalytically inactive, has a variety of biological activities, including cytotoxic, antibacterial, inflammatory, antifungal activities. Herein, a Lys49 phospholipase A2, denominated CoaTx-II from Crotalus oreganus abyssus, was purified and structurally and pharmacologically characterized. CoaTx-II was isolated with a high degree of purity by a combination of two chromatographic steps; molecular exclusion and reversed-phase high performance liquid chromatography. This toxin is dimeric with a mass of 13868.2 Da (monomeric form), as determined by mass spectrometry. CoaTx-II is rich in Arg and Lys residues and displays high identity with other Lys49 PLA2 homologues, which have high isoelectric points. The structural model of dimeric CoaTx-II shows that the toxin is non-covalently stabilized. Despite its enzymatic inactivity, in vivo CoaTx-II caused local muscular damage, characterized by increased plasma creatine kinase and confirmed by histological alterations, in addition to an inflammatory activity, as demonstrated by mice paw edema induction and pro-inflammatory cytokine IL-6 elevation. CoaTx-II also presents antibacterial activity against gram negative (Pseudomonas aeruginosa 31NM, Escherichia coli ATCC 25922) and positive (Staphyloccocus aureus BEC9393 and Rib1) bacteria. Therefore, data show that this newly purified toxin plays a central role in mediating the degenerative events associated with envenomation, in addition to demonstrating antibacterial properties, with potential for use in the development of strategies for antivenom therapy and combating antibiotic-resistant bacteria.

Anti-Atherogenic Properties of Allium ursinum Liophylisate: Impact on Lipoprotein Homeostasis and Cardiac Biomarkers in Hypercholesterolemic Rabbits.

The present investigation evaluates the capacity of Allium ursinum (wild garlic) leaf lyophilisate (WGLL; alliin content: 0.261%) to mitigate cardiovascular damage in hypercholesterolemic rabbits. New Zealand rabbits were divided into three groups: (i) cholesterol-free rabbit chow (control); (ii) rabbit chow containing 2% cholesterol (hypercholesterolemic, HC); (iii) rabbit chow containing 2% cholesterol + 2% WGLL (hypercholesterolemic treated, HCT); for eight weeks. At the zero- and eight-week time points, echocardiographic measurements were made, along with the determination of basic serum parameters. Following the treatment period, after ischemia-reperfusion injury, hemodynamic parameters were measured using an isolated working heart model. Western blot analyses of heart tissue followed for evaluating protein expression and histochemical study for the atheroma status determination. WGLL treatment mediated increases in fractional shortening; right ventricular function; peak systolic velocity; tricuspidal annular systolic velocity in live animals; along with improved aortic and coronary flow. Western blot analysis revealed WGLL-associated increases in HO-1 protein and decreases in SOD-1 protein production. WGLL-associated decreases were observed in aortic atherosclerotic plaque coverage, plasma ApoB and the activity of LDH and CK (creatine kinase) in plasma. Plasma LDL was also significantly reduced. The results clearly demonstrate that WGLL has complex cardioprotective effects, suggesting future strategies for its use in prevention and therapy for atherosclerotic disorders.

Protein-Anchoring Therapy of Biglycan for Mdx Mouse Model of Duchenne Muscular Dystrophy.

Duchenne muscular dystrophy (DMD) is a devastating muscle disease caused by loss-of-function mutations in DMD encoding dystrophin. No rational therapy is currently available. Utrophin is a paralog of dystrophin and is highly expressed at the neuromuscular junction. In mdx mice, utrophin is naturally upregulated throughout the muscle fibers, which mitigates muscular dystrophy. Protein-anchoring therapy was previously reported, in which a recombinant extracellular matrix (ECM) protein is delivered to and anchored to a specific target using its proprietary binding domains. Being prompted by a report that intramuscular and intraperitoneal injection of an ECM protein, biglycan, upregulates expression of utrophin and ameliorates muscle pathology in mdx mice, protein-anchoring therapy was applied to mdx mice. Recombinant adeno-associated virus serotype 8 (rAAV8) carrying hBGN encoding human biglycan was intravenously injected into 5-week-old mdx mice. The rAAV8-hBGN treatment improved motor deficits and decreased plasma creatine kinase activities. In muscle sections of treated mice, the number of central myonuclei and the distribution of myofiber sizes were improved. The treated mice increased gene expressions of utrophin and β1-syntrophin, as well as protein expressions of biglycan, utrophin, γ-sarcoglycan, dystrobrevin, and α1-syntrophin. The expression of hBGN in the skeletal muscle of the treated mice was 1.34-fold higher than that of the native mouse Bgn (mBgn). The low transduction efficiency and improved motor functions suggest that biglycan expressed in a small number of muscle fibers was likely to have been secreted and anchored to the cell surface throughout the whole muscular fibers. It is proposed that the protein-anchoring strategy can be applied not only to deficiency of an ECM protein as previously reported, but also to augmentation of a naturally induced ECM protein.

Effect of hyperoxygenated solution on myocardial injury in rats with acute carbon monoxide poisoning

Objective To evaluate the effect of hyperoxygenated solution on myocardial injury in the rats with acute carbon monoxide (CO) poisoning. Methods Thirty pathogen-free adult male Sprague-Dawley rats, weighing 250-300 g, were randomly divided into 5 groups (n=6 each) using a random number table: control group (C group), acute CO poisoning group (ACP group), and different doses of hyperoxygenated solution groups (HP1-3 groups). CO 120 ml/kg was injected intraperitoneally to establish the model of acute CO poisoning.Hyperoxygenated solution 10, 15 and 20 ml/kg were infused via the caudal vein at 1 h after intraperitoneal injection of CO in HP1-3 groups, respectively.At 24 h after intraperitoneal injection of CO, blood samples were collected from the caudal vein for determination of plasma creatine kinase (CK), creatine kinase-MB (CK-MB), lactic dehydrogenase (LDH) and alpha-hydroxybutyrate acid dehydrogenase (α-HBDH) activities using the automatic biochemical analyzer.The rats were then sacrificed, and myocardial specimens were obtained for examination of the pathological changes with a light microscope. Results Compared with group C, the plasma LDH, α-HBDH, CK and CK-MB activities were significantly increased in ACP and HP1-3 groups (P<0.01). Compared with group ACP, the plasma LDH, α-HBDH, CK and CK-MB activities were significantly decreased in HP1-3 groups (P<0.05 or 0.01). Compared with group HP1, the plasma LDH, α-HBDH, CK and CK-MB activities were significantly decreased in HP2, 3 groups (P<0.05). The pathological changes of myocardium were significantly attenuated in HP1-3 groups as compared with group ACP. Conclusion Hyperoxygenated solution can attenuate myocardial injury in the rats with acute CO poisoning. Key words: Oxygen; Carbon monoxide poisoning; Myocardium

Intensified training periods: when much is to too much?

[b]Introduction.[/b] This study has been undertaken in order to examine the usefulness of selected biomarkers as commonly used for monitoring of biological responses to an intensified training period.[b]Material and methods.[/b] The subject was monitored day-by-day throughout an a 2-wk training period, which preceded a pre competition 10-day taper period. Morning blood biochemical indices, perceived sleep quality (SQ), hand-grip strength (H-GS), visuo-attentional motor level (VAM) were assayed and provided to the coach no later than 3 hours after blood sampling and just before the morning training session. Overnight collected urine samples were stored frozen until determination of urinary creatinine, urea and free cortisol.[b]Results. [/b]During the first half of the training period plasma creatine kinase tended to increase, whereas T tended to decrease. In the morning of the 10th day of the period the testosterone rapidly decreased under the lower physiological limit, that was associated with strongly elevated urinary excretion cortisol and urea, deteriorated SQ, H-GS, VAM and reported malaise. Judoka had to stop training. After 2 days of rest period all these psycho-physiological indices returned to the baseline values, judoka felt better and declared his willingness to resume the training.[b]Conclusions.[/b] The results showed usefulness of comprehensive biometric monitoring across an intensified training period. Excessive training with inadequate rest periods resulted in unpredictable, acute psycho-physical indispositions along with changes in the physiological markers similar to those noted during chronic fatigue. Considering very short length of the duration of that syndrome, it does meet criteria of overtraining/overreaching.

Protective effect by maximal isometric contractions against maximal eccentric exercise-induced muscle damage of the knee extensors

ABSTRACTThis study investigated whether maximal voluntary isometric contractions (MVIC) performed before maximal eccentric contractions (MaxEC) would attenuate muscle damage of the knee extensors. Untrained men were placed to an experimental group that performed 6 sets of 10 MVIC at 90° knee flexion 2 weeks before 6 sets of 10 MaxEC or a control group that performed MaxEC only (n = 13/group). Changes in muscle damage markers were assessed before to 5 days after each exercise. Small but significant changes in maximal voluntary concentric contraction torque, range of motion (ROM) and plasma creatine kinase (CK) activity were evident at immediately to 2 days post-MVIC (p < 0.05), but other variables (e.g. thigh girth, myoglobin concentration, B-mode echo intensity) did not change significantly. Changes in all variables after MaxEC were smaller (p < 0.05) by 45% (soreness)–67% (CK) for the experimental than the control group. These results suggest that MVIC conferred potent protective effect against MaxEC-induced muscle damage.

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Snake venoms are rich and intriguing sources of biologically-active molecules that act on target cells, modulating a diversity of physiological functions and presenting promising pharmacological applications. Lys49 phospholipase A2 is one of the multifunctional proteins present in these complex secretions and, although catalytically inactive, has a variety of biological activities, including cytotoxic, antibacterial, inflammatory, antifungal activities. Herein, a Lys49 phospholipase A2, denominated CoaTx-II from Crotalus oreganus abyssus, was purified and structurally and pharmacologically characterized. CoaTx-II was isolated with a high degree of purity by a combination of two chromatographic steps; molecular exclusion and reversed-phase high performance liquid chromatography. This toxin is dimeric with a mass of 13868.2 Da (monomeric form), as determined by mass spectrometry. CoaTx-II is rich in Arg and Lys residues and displays high identity with other Lys49 PLA2 homologues, which have high isoelectric points. The structural model of dimeric CoaTx-II shows that the toxin is non-covalently stabilized. Despite its enzymatic inactivity, in vivo CoaTx-II caused local muscular damage, characterized by increased plasma creatine kinase and confirmed by histological alterations, in addition to an inflammatory activity, as demonstrated by mice paw edema induction and pro-inflammatory cytokine IL-6 elevation. CoaTx-II also presents antibacterial activity against gram negative (Pseudomonas aeruginosa 31NM, Escherichia coli ATCC 25922) and positive (Staphyloccocus aureus BEC9393 and Rib1) bacteria. Therefore, data show that this newly purified toxin plays a central role in mediating the degenerative events associated with envenomation, in addition to demonstrating antibacterial properties, with potential for use in the development of strategies for antivenom therapy and combating antibiotic-resistant bacteria.

Association of Temperament and Acute Stress Responsiveness with Productivity, Feed Efficiency, and Methane Emissions in Beef Cattle: An Observational Study.

The aim of this study was to assess individual differences in temperament and stress response and quantify their impact on feed efficiency, performance, and methane (CH4) emissions in beef cattle. Eighty-four steers (castrated males) (Charolais or Luing) were used. Temperament was assessed using two standardized tests: restlessness when restrained [crush score (CS)] and flight speed (FS) on release from restraint. Over a 56-day period individual animal dry matter intake (DMI) and weekly body weight was measured. Ultrasound fat depth was measured at the end of 56 days. Average daily gain (ADG), feed conversion ratio (FCR), and residual feed intake (RFI) were calculated. After the 56-day test period, animals were transported in groups of six/week to respiration chamber facilities. Blood samples were taken before and 0, 3, 6, and 9 h after transport. Plasma cortisol, creatine kinase (CK), glucose, and free fatty acids (FFA) were determined to assess physiological stress response. Subsequently, CH4 emissions were measured over a 3-day period in individual respiration chambers. CS (1.7 ± 0.09) and FS (1.6 ± 0.60 m/s) were repeatable (0.63 and 0.51, respectively) and correlated (r = 0.36, P < 0.001). Plasma cortisol, CK, and FFA concentrations increased after transport (P = 0.038, P = 0.006, and P < 0.001, respectively). Temperament (CS) and CK concentration were correlated (r = 0.29; P = 0.015). The extreme group analysis reveals that excitable animals (FS; P = 0.032) and higher stress response (cortisol, P = 0.007; FFA, P = 0.007; and CK, P = 0.003) were associated with lower DMI. ADG was lower in more temperamental animals (CS, P = 0.097, and FS, P = 0.030). Fat depth was greater in steers showing calmer CS (P = 0.026) and lower plasma CK (P = 0.058). Temperament did not show any relationship with RFI or CH4 emissions. However, steers with higher cortisol showed improved feed efficiency (lower FCR and RFI) (P < 0.05) and greater CH4 emissions (P = 0.017). In conclusion, agitated temperament and higher stress responsiveness is detrimental to productivity. A greater stress response is associated with a reduction in feed intake that may both increase the efficiency of consumed feed and the ratio of CH4 emissions/unit of feed. Therefore, temperament and stress response should be considered when designing strategies to improve efficiency and mitigate CH4 emissions in beef cattle.

Panax ginseng and salvia miltiorrhiza supplementation abolishes eccentric exercise-induced vascular stiffening: a double-blind randomized control trial.

BackgroundMuscle damage induced by unaccustomed or eccentric exercise results in delayed onset vascular stiffening. We tested the hypothesis that a 7-day supplementation of panax ginseng and salvia miltiorrhiza prior to an acute eccentric exercise could attenuate arterial stiffening.MethodsBy using a double-blind study placebo-controlled randomized design, subjects were randomly assigned to either the Chinese herb (N = 12) or the placebo group (N = 11) and performed a downhill running (eccentric exercise) trial and a control (seated rest) trial.ResultsMuscle soreness increased 1–2 days after exercise similarly in both groups, whereas the herb group demonstrated a faster recovery on active range of motion. Plasma creatine kinase concentration increased significantly at 24 h in both groups but the magnitude of increase was attenuated in the herb group. Arterial stiffness as measured by carotid-femoral pulse wave velocity increased significantly at 24 h in the placebo group but such increase was absent in the herb group. Flow-mediated dilation did not change in either group. Plasma concentrations of CRP and IL-6 increased in the placebo group but no such increases were observed in the herb group. Changes in arterial stiffness induced by eccentric exercise were associated with the corresponding changes in IL-6 (r = 0.46, P < 0.05).ConclusionsA short-term Chinese herb supplementation of panax ginseng and salvia miltiorrhiza ameliorated the delayed onset vascular stiffening induced by acute downhill running exercise.Trial registrationClinicalTrials.gov: NCT02007304. Registered Dec. 5, 2013)

A Calsequestrin-1 Mutation Associated with a Skeletal Muscle Disease Alters Sarcoplasmic Ca2+ Release.

An autosomal dominant protein aggregate myopathy, characterized by high plasma creatine kinase and calsequestrin-1 (CASQ1) accumulation in skeletal muscle, has been recently associated with a missense mutation in CASQ1 gene. The mutation replaces an evolutionarily-conserved aspartic acid with glycine at position 244 (p.D244G) of CASQ1, the main sarcoplasmic reticulum (SR) Ca2+ binding and storage protein localized at the terminal cisternae of skeletal muscle cells. Here, immunocytochemical analysis of myotubes, differentiated from muscle-derived primary myoblasts, shows that sarcoplasmic vacuolar aggregations positive for CASQ1 are significantly larger in CASQ1-mutated cells than control cells. A strong co-immuno staining of both RyR1 and CASQ1 was also noted in the vacuoles of myotubes and muscle biopsies derived from patients. Electrophysiological recordings and sarcoplasmic Ca2+ measurements provide evidence for less Ca2+ release from the SR of mutated myotubes when compared to that of controls. These findings further clarify the pathogenic nature of the p.D244G variant and point out defects in sarcoplasmic Ca2+ homeostasis as a mechanism underlying this human disease, which could be distinctly classified as “CASQ1-couplonopathy”.

Effects of Resveratrol Supplementation and Exercise Training on Exercise Performance in Middle-Aged Mice.

Resveratrol (RES) has antioxidative, anti-inflammatory, anticancer, antidiabetic, antiasthmatic, antalgic, and anti-fatigue activities. Exercise training (ET) improves frailty resulting from aging. This study evaluated the effects of a combination of RES supplementation and ET on the exercise performance of aged mice. C57BL/6J mice (16 months old) were randomly divided into four groups: an older control group (OC group), supplementation with RES group (RES group), ET group (ET group), and a combination of ET and RES supplementation group (ET+RES group). Other 10-week-old mice were used as a young control group (Y-Ctrl group). In this study, exercise performance was evaluated using forelimb grip strength and exhaustive swimming time, as well as levels of plasma lactate, ammonia, glucose, and creatine kinase after an acute swimming exercise. Our results showed that the forelimb grip strength of mice in the ET+RES group was significantly higher than those in the OC, RES, and ET groups (by 1.3-, 1.2-, and 1.1-fold, respectively, p < 0.05), and exhibited no difference with the Y-Ctrl group. The endurance swimming test showed that swimming times of the ET and ET+RES groups were significantly longer than those of the OC and RES groups. Moreover, plasma lactate and ammonia levels of the ET + RES group after acute swimming exercise were significantly lower compared to the OC group (p < 0.05). Thus, it was suggested that by combining RES supplementation with ET for 4 weeks, the muscle strength and endurance performance of aged mice were significantly improved compared to the single intervention with either RES or ET alone. This combination might help shorten the extent of deterioration accompanying the aging process.

Determinants of recovery from a 161-km ultramarathon

ABSTRACTThe primary study objective was to identify determinants of short-term recovery from a 161-km ultramarathon. Participants completed 400 m runs at maximum speed before the race and on days 3 and 5 post-race, provided a post-race blood sample for plasma creatine kinase (CK) concentration, and provided lower body muscle pain and soreness ratings (soreness, 10-point scale) and overall muscular fatigue scores (fatigue, 100-point scale) pre-race and for 7 days post-race. Among 72 race finishers, soreness and fatigue had statistically returned to pre-race levels by 5 days post-race; and 400 m times at days 3 and 5 remained 26% (P = 0.001) and 12% (P = 0.01) slower compared with pre-race, respectively. CK best modelled soreness, fatigue and per cent change in post-race 400 m time. Runners with the highest CKs had 1.5 points higher (P < 0.001) soreness and 11.2 points higher (P = 0.006) fatigue than runners with the lowest CKs. For the model of 400 m time, a significant interaction of time with CK (P < 0.001) indicates that higher CKs were linked with a slower rate of return to pre-race 400 m time. Since post-race CK was the main modifiable determinant of recovery following the ultramarathon, appropriate training appears to be the optimal approach to enhance ultramarathon recovery.

Equine atypical myopathy associated with sycamore seed ingestion in a Przewalski foal

One of the 172 UK cases of equine atypical myopathy (EAM) reported to the Atypical Myopathy Alert Group (AMAG) in 2014 was that of a five-month old male Przewalski horse (Equus ferus przewalskii), resident at ZSL Whipsnade Zoo, UK. The foal presented initially with sudden-onset and repeated stretching of the neck as if dysphagic, with progressive weakness (including lying down), sweating and an unresponsive demeanour. General anaesthesia, induced with a combination of etorphine, midazolam and hyaluronidase, was required for each examination and subsequent treatment of the foal. Initial biochemical analysis showed a markedly increased plasma creatine kinase (CK) activity of 105,001 U/L, an increased aspartate amino transferase (AST) activity of 4194 U/L and a mildly increased inorganic phosphorus concentration of 2.35 mmol/L. The foal was unresponsive to treatment and had to be euthanased. Skeletal musculature and the myocardium showed the most significant pathological changes, with histological evidence of rhabdomyolysis, whilst urine organic acid analysis and an abnormal organic acid serum profile were supportive of multiple acyl Co-A dehydrogenase deficiency typical of EAM. This is the first description of EAM in a non-domestic equid.

Treatment with oestrogen-receptor agonists or oxytocin in conjunction with exercise protects against myocardial infarction in ovariectomized rats.

What is the central question of this study? Could the activation of oxytocin or oestrogen receptors be protective against myocardial injury after ovariectomy? If so, would exercising have an additional ameliorating effect? What is the main finding and its importance? The results revealed that when accompanied by exercise, both oestrogen receptor agonists and oxytocin improved cardiac dysfunction, inhibited the generation of pro-inflammatory cytokines and reduced myocardial injury in ovariectomized female rats, suggesting a new approach for protecting postmenopausal women against ischaemia-induced myocardial injury. To investigate the putative protective effects of oxytocin or oestrogen receptor agonists against myocardial injury of ovariectomized sedentary or exercised rats, female Sprague-Dawley rats assigned to sham-operated control and ovariectomized (OVX) groups were kept sedentary or undertook swimming exercise for 4 weeks and were treated with saline, an oestrogen receptor (ER) β (DPN) or ERα agonist (PPT) or oxytocin. Ovariectomy increased weight gain and anxiety in sedentary rats, whereas exercise prevented weight gain. When accompanied by exercise, both ER agonists and oxytocin inhibited weight gain and anxiety; oxytocin, in the absence or presence of exercise, increased the left ventricular diastolic dimensions and ejection fraction, whereas ER agonists also increased left ventricular diameter when given to exercised rats. Upon the induction of myocardial ischaemia-reperfusion in the OVX rats, plasma creatine kinase-(muscle-brain) was depressed by PPT and oxytocin, whereas DPN, PPT and OT reduced plasminogen activator inhibitor-1 concentrations. The increased tumour necrosis factor-α concentration in OVX rats was also suppressed by exercise or DPN, PPT or oxytocin treatments, whereas the interleukin-6 concentration was diminished by all the treatments when given in conjunction with exercise. Disorganization of cardiac muscle fibres was reduced in all exercised rats. Oestrogen receptor agonists, as well as oxytocin, in conjunction with exercise may be effective new therapeutics to protect against myocardial ischaemia in postmenopausal women.

Effects of Branched‐Chain Amino Acid Supplementation on Exercise Performance and Recovery in Highly Endurance‐Trained Athletes

Branched‐chain amino acid (BCAA) supplementation has recently entered the spotlight as a potentially key nutritional component to skeletal muscle recovery during periods of high training volume in endurance athletes. The purpose of this study was to examine the effects of BCAA supplementation on anaerobic and aerobic performance, substrate utilization during constant‐load exercise to exhaustion, and plasma creatine kinase and lactate dehydrogenase levels during post‐exercise recovery. Nine well‐trained cyclists (5 male, 4 female) underwent a morning session and an afternoon session of exercise testing under BCAA or Placebo conditions. Morning tests included two 15‐second Wingates to determine peak and mean anaerobic power output, followed by an incremental test to exhaustion to determine peak oxygen consumption (VO2peak). Afternoon tests included two 15‐second Wingates, followed by a constant‐load exercise to exhaustion at 75% VO2peak, during which only water was provided. During the latter test, pulmonary gas exchange, blood lactate and blood glucose were periodically measured to monitor substrate utilization. Pre‐ and post‐exercise blood tests were conducted to quantify plasma creatine kinase and lactate dehydrogenase levels as biomarkers for muscle damage. Post‐exercise ratings of perceived soreness were also collected. Subjects were then instructed to continue training for at least 2000 MET‐min/week for the next four weeks while supplementing with either a BCAA (5 g amino acids + 56 g carbohydrates) or Placebo (56 g carbohydrates) powdered drink during each workout. At the completion of the four weeks, subjects repeated two 15‐second Wingates and an incremental test to exhaustion to determine any differences in anaerobic and aerobic power due to BCAA or Placebo supplementation. There were no differences in VO2peak pre‐ and post‐training between BCAA and placebo conditions. Peak anaerobic power was slightly improved when athletes supplemented their training with the BCAA drink. The total energy expenditure achieved during the constant‐load exercise test was not different between conditions. Post‐exercise plasma creatine kinase levels were significantly reduced with BCAA compared with Placebo, while there were no differences in plasma lactate dehydrogenase levels. Post‐exercise leg muscle soreness was slightly lower with BCAA supplementation, although not significant. In conclusion, BCAA supplementation with endurance training may augment adaptations in muscle anaerobic power and post‐exercise recovery in well‐trained athletes.Support or Funding InformationThis research was supported by the Saint Mary's College Faculty Development Fund and a gift from GU Energy Labs, Berkeley, CA.

Angiotensin IV protects cardiac reperfusion injury by inhibiting apoptosis and inflammation via AT4R in rats

Angiotensin IV (Ang IV) is formed by aminopeptidase N from Ang III by removing the first N-terminal amino acid. Previously, we reported that Ang III has some cardioprotective effects against global ischemia in Langendorff heart. However, it is not clear whether Ang IV has cardioprotective effects. The aim of the present study was to evaluate the effect of Ang IV on myocardial ischemia-reperfusion (I/R) injury in rats. Before ischemia, male Sprague-Dawley rats received Ang IV (1mg/kg/day) for 3 days. Anesthetized rats were subjected to 45min of ischemia by ligation of left anterior descending coronary artery followed by reperfusion and then, sacrificed 1 day or 1 week after reperfusion. Plasma creatine kinase (CK) and lactate dehydrogenase (LDH) concentrations, and infarct size were measured. Quantitative analysis of apoptotic and inflammatory proteins in ventricles were performed using Western blotting. Pretreatment with Ang IV attenuated I/R-induced increases in plasma CK and LDH levels, and infarct size, which were blunted by Ang IV receptor (AT4R) antagonist and but not by antagonist for AT1R, AT2R, or Mas receptor. I/R increased Bax, caspase-3 and caspase-9 protein levels, and decreased Bcl-2 protein level in ventricles, which were blunted by Ang IV. I/R-induced increases in TNF-α, MMP-9, and VCAM-1 protein levels in ventricles were also blunted by Ang IV. Ang IV increased the phosphorylation of Akt and mTOR. These effects were attenuated by co-treatment with AT4R antagonist or inhibitors of downstream signaling pathway. Myocardial dysfunction after reperfusion was improved by Ang IV. These results suggest that Ang IV has cardioprotective effect against I/R injury by inhibiting apoptosis via AT4R and PI3K-Akt-mTOR pathway.

L-glutamine and l-alanine supplementation increase glutamine-glutathione axis and muscle HSP-27 in rats trained using a progressive high-intensity resistance exercise.

In this study we investigated the chronic effects of oral l-glutamine and l-alanine supplementation, either in their free or dipeptide form, on glutamine-glutathione (GLN-GSH) axis and cytoprotection mediated by HSP-27 in rats submitted to resistance exercise (RE). Forty Wistar rats were distributed into 5 groups: sedentary; trained (CTRL); and trained supplemented with l-alanyl-l-glutamine, l-glutamine and l-alanine in their free form (GLN+ALA), or free l-alanine (ALA). All trained animals were submitted to a 6-week ladder-climbing protocol. Supplementations were offered in a 4% drinking water solution for 21 days prior to euthanasia. Plasma glutamine, creatine kinase (CK), myoglobin (MYO), and erythrocyte concentration of reduced GSH and glutathione disulfide (GSSG) were measured. In tibialis anterior skeletal muscle, GLN-GSH axis, thiobarbituric acid reactive substances (TBARS), and the expression of heat shock factor 1 (HSF-1), 27-kDa heat shock protein (HSP-27), and glutamine synthetase were determined. In CRTL animals, high-intensity RE reduced muscle glutamine levels and increased GSSG/GSH rate and TBARS, as well as augmented plasma CK and MYO levels. Conversely, l-glutamine-supplemented animals showed an increase in plasma and muscle levels of glutamine, with a reduction in GSSG/GSH rate, TBARS, and CK. Free l-alanine administration increased plasma glutamine concentration and lowered muscle TBARS. HSF-1 and HSP-27 were high in all supplemented groups when compared with CTRL (p < 0.05). The results presented herein demonstrate that l-glutamine supplemented with l-alanine, in both a free or dipeptide form, improve the GLN-GSH axis and promote cytoprotective effects in rats submitted to high-intensity RE training.

Biochemical and functional studies of ColTx-I, a new myotoxic phospholipase A2 isolated from Crotalus oreganus lutosus (Great Basin rattlesnake) snake venom

Commonly, phospholipases A2 (PLA2s) play key roles in the pathogenesis of the local tissue damage characteristic of crotaline and viperine snake envenomations. Crotalus oreganus lutosus snake venom has not been extensively studied; therefore, the characterization of its components represents a valuable biotechnological tool for studying pathophysiological processes of envenoming and for gaining a deeper understanding of its biological effects. In this study, for the first time, a basic PLA2 myotoxin, ColTx-I, was purified from C. o. lutosus through two chromatographic steps. ColTx-I is monomeric with calculated molecular mass weight (Mw) of 14,145 Da and a primary structure closely related to basic PLA2s from viperid venoms. The pure enzyme has a specific activity of 15.87 ± 0.65 nmol/min/mg at optimal conditions (pH 8.0 and 37 °C). ColTx-I activity was found to be dependent on Ca2+, as its substitution by other ionic species as well as the addition of chelating agents significantly reduced its phospholipase activity. In vivo, ColTx-I triggered dose-dependent inflammatory responses, measured using the paw edema model, with an increase in IL-6 levels, systemic and local myotoxicity, characterized by elevated plasma creatine kinase activity. ColTx-I induced a complex series of degenerative events associated with edema, inflammatory infiltrate and skeletal muscle necrosis. These biochemical and functional results suggest that ColTx-I, a myotoxic and inflammatory mediator, plays a relevant role in C. o. lutosus envenomation. Thus, detailed studies on its mechanism of action, such as evaluating the synergism between ColTx-I and other venom components may reveal targets for the development of more specific and effective therapies.

Type of Ground Surface during Plyometric Training Affects the Severity of Exercise-Induced Muscle Damage.

The purpose of this study was to compare the changes in the symptoms of exercise-induced muscle damage from a bout of plyometric exercise (PE; 10 × 10 vertical jumps) performed in aquatic, sand and firm conditions. Twenty-four healthy college-aged men were randomly assigned to one of three groups: Aquatic (AG, n = 8), Sand (SG, n = 8) and Firm (FG, n = 8). The AG performed PE in an aquatic setting with a depth of ~130 cm. The SG performed PE on a dry sand surface at a depth of 20 cm, and the FG performed PE on a 10-cm-thick wooden surface. Plasma creatine kinase (CK) activity, delayed onset muscle soreness (DOMS), knee range of motion (KROM), maximal isometric voluntary contraction (MIVC) of the knee extensors, vertical jump (VJ) and 10-m sprint were measured before and 24, 48 and 72 h after the PE. Compared to baseline values, FG showed significantly (p < 0.05) greater changes in CK, DOMS, and VJ at 24 until 48 h. The MIVC decreased significantly for the SG and FG at 24 until 48 h post-exercise in comparison to the pre-exercise values. There were no significant (p > 0.05) time or group by time interactions in KROM. In the 10-m sprint, all the treatment groups showed significant (p < 0.05) changes compared to pre-exercise values at 24 h, and there were no significant (p > 0.05) differences between groups. The results indicate that PE in an aquatic setting and on a sand surface induces less muscle damage than on a firm surface. Therefore, training in aquatic conditions and on sand may be beneficial for the improvement of performance, with a concurrently lower risk of muscle damage and soreness.

Influence of football match time–motion parameters on recovery time course of muscle damage and jump ability

ABSTRACTWe analysed the time course of recovery of creatine kinase (CK) and countermovement jump (CMJ) parameters after a football match, and correlations between changes in these variables and match time–motion parameters (GPS-accelerometry) in 15 U-19 elite male players. Plasma CK and CMJ height (CMJH), average concentric force (CMJCON) and average eccentric force (CMJECC) were assessed 2 h before and 30 min, 24 h and 48 h post-match. There were substantially higher CK levels 30 min, 24 h and 48 h (ES: 0.43, 0.62, 0.40, respectively), post-match. CMJECC (ES: −0.38), CMJH (ES: −0.35) decreased 30 min post, CMJCON (ES: −0.35), CMJECC (ES: −0.35) and CMJH (ES: −1.35) decreased 24 h post, and CMJCON (ES: −0.41) and CMJH (ES: −0.53) decreased 48 h post. We found correlations between distance covered at velocities ≤21 km · h−1 and changes in CK at 24 h (r = 0.56) and at 48 h (r = 0.54) and correlations between CK and distance covered >14 km · h−1 (r = 0.50), accelerations (r = 0.48), and decelerations (r = 0.58) at 48 h. Changes in CMJCON 30 min and 24 h post (both r = −0.68) correlated with impacts >7.1·G. Decelerations >2 m · s−2 correlated with changes CMJCON (r = −0.49) at 48 h and CMJECC (r = −0.47) at 30 min. Our results suggest that match GPS-accelerometry parameters may predict muscle damage and changes in components of neuromuscular performance immediately and 24–48 h post-match.