Muscle Lactate Research Articles

The four subunits of rabbit skeletal muscle lactate dehydrogenase do not exert their catalytic action additively

Oligomeric enzymes containing multiple active sites are usually considered to perform their catalytic action at higher rates when compared with their monomeric counterparts. This implies, in turn, that the activity performed by different holoenzyme subunits features additivity. Nevertheless, the extent of this additivity occurring in holoenzymes is far from being adequately understood. To tackle this point, we used tetrameric rabbit lactate dehydrogenase (rbLDH) as a model system to assay the reduction of pyruvate catalysed by this enzyme at the expense of β-NADH under pre-steady-state conditions. In particular, we observed the kinetics of reactions triggered by concentrations of β-NADH equimolar to 1, 2, 3, or all 4 subunits of the rbLDH holoenzyme, in the presence of an excess of pyruvate. Surprisingly, when the concentration of the limiting reactant exceeded that of a single holoenzyme subunit, we observed a sharp slowdown of the enzyme conformational rearrangements associated to the generation and the release of l-lactate. Furthermore, using a model to interpret the complex kinetics observed under the highest concentration of the limiting reactant, we estimated the diversity of the rates describing the action of the different rbLDH subunits.

Stem cell biotherapy: A new remedy for Trichinella spiralis-induced inflammatory myopathy.

Trichinella spiralis (T. spiralis)-induced myopathy is an inflammatory myopathy that is difficult to treat unless the parasite is combated in its early intestinal phase before it reaches the muscles. This study aimed to evaluate the effect of local mesenchymal stem cell (MSC) therapy on T. spiralis-induced inflammatory myopathy in rats. Rats were divided into four groups: Group 1 (non-infected non-treated group); Group 2 (infected non-treated group); Group 3 (infected albendazole (ABZ)-treated group); and Group 4 (infected MSC-treated group). Their muscle status was assessed physiologically with the righting reflex and electromyography (EMG), parasitologically with the total muscle larval count, histopathologically with hematoxylin and eosin and Mallory's trichrome stains, as well as immunohistochemically for myogenin as a marker of muscle regeneration. Additionally, serum muscle enzymes creatine kinase (CK) and lactate dehydrogenase (LDH), as well as muscle matrix metalloproteinases MMP1 and MMP9, were assayed. Finally, the immunological response was assessed by measuring the levels of the muscle inflammatory cytokines tumor necrosis factor-alpha (TNF-α), interferon-gamma (INF-γ), and interleukin-4 (IL-4). Our findings revealed that MSC therapy markedly improved muscle EMG and righting reflex, as well as the histopathological appearance of the muscles, reduced inflammatory cellular infiltrates, and increased myogenin immunostaining. It also reduced serum CK and LDH levels, as well as muscle INF-γ, TNF-α, IL-4, MMP1, and MMP9 levels. However, it had no effect on the total muscle larval count. Accordingly, due to its anti-inflammatory properties and muscle-regenerative effect, MSC therapy could be a promising new remedy for T. spiralis-induced myopathy.

Early decreased respiratory chain capacity in resuscitated experimental sepsis is a major contributor to lactate production.

Increased plasma lactate levels in patients with sepsis may be due to insufficient oxygen delivery, but mitochondrial dysfunction or accelerated glycolysis may also contribute. We studied the effect of the latter on muscle metabolism by using microdialysis in a sepsis model with sustained oxygen delivery and decreased energy consumption or mitochondrial blockade. Pigs were subjected to continuous E. coli infusion (sepsis group, n = 12) or saline infusion (sham group, n = 4) for 3 hours (h). Protocolized interventions were applied to normalize the oxygen delivery and blood pressure. Microdialysis catheters were used to monitor muscle metabolism (naïve). The same catheters were used to block the electron transport chain with cyanide or the Na+/K+-ATPase inhibitor, ouabain locally. All pigs in the sepsis group had positive blood cultures and a Sequential Organ Failure Assessment (SOFA) score increase by at least 2, fulfilling the sepsis criteria. Plasma lactate was higher in the sepsis group than in the sham group (p < 0.001), whereas muscle glucose was lower in the sepsis group (p < 0.01). There were no changes in muscle lactate levels over time but lactate to pyruvate ratio (LPR) was elevated in the Sepsis vs. the Sham group (p < 0.05). Muscle lactate, LPR, and glutamate levels were higher in the sepsis group than in the sham group in the cyanide catheters (p < 0.001, all comparisons) and did not normalize in the former group. In this experimental study on resuscitated sepsis, we observed increased aerobic metabolism and preserved mitochondrial function. Sepsis and electron transport chain inhibition led to increased LPR, suggesting a decreased mitochondrial reserve capacity in early sepsis.

Changes in salivary biomarkers of stress, inflammation, redox status, and muscle damage due to Streptococcus suis infection in pigs

BackgroundStreptococcus suis (S. suis) is a Gram-positive bacteria that infects pigs causing meningitis, arthritis, pneumonia, or endocarditis. This increases the mortality in pig farms deriving in severe economic losses. The use of saliva as a diagnostic fluid has various advantages compared to blood, especially in pigs. In this study, it was hypothesized that saliva could reflect changes in different biomarkers related to stress, inflammation, redox status, and muscle damage in pigs with S. suis infection and that changes in these biomarkers could be related to the severity of the disease.ResultsA total of 56 growing pigs from a farm were selected as infected pigs (n = 28) and healthy pigs (n = 28). Results showed increases in biomarkers related to stress (alpha-amylase and oxytocin), inflammation (haptoglobin, inter-alpha-trypsin inhibitor heavy chain 4 (ITIH4), total protein, S100A8-A9 and S100A12), redox status (advanced oxidation protein producs (AOPP)) and muscle damage (creatine kinase (CK), CK-MB, troponin I, lactate, aspartate aminotransferase, and lactate dehydrogenase). An increase in adenosine deaminase (ADA), procalcitonin, and aldolase in infected animals were also observed, as previously described. The grade of severity of the disease indicated a significant positive correlation with total protein concentrations, aspartate aminotransferase, aldolase, and AOPP.ConclusionsThis report revealed that S. suis infection caused variations in analytes related to stress, inflammation, redox status, and muscle damage in the saliva of pigs and these can be considered potential biomarkers for this disease.

The pyruvate kinase of the whiteleg shrimp Litopenaeus vannamei: Gene structure and responses to short term hypoxia

The shrimp Litopenaeus vannamei is the main farmed crustacean worldwide. This shrimp suffers environmental changes in oxygen availability that affect its energy metabolism. Pyruvate kinase (PK) catalyzes the last reaction of glycolysis and is key for the regulation of glycolysis and gluconeogenesis. There is ample knowledge about mammalian PK, but in crustaceans, the information is very scarce. In this study, we analyzed in silico the structures of the PK gene and protein. Also, the effects of hypoxia on gene expression, enzymatic activity, glucose, and lactate in hepatopancreas and muscle were analyzed. The PK gene is 15,103 bp and contains 11 exons and 10 introns, producing four mRNA variants by alternative splicing and named PK1, PK2, PK3 and PK4, that results in two proteins with longer C-terminus and two with a 12 bp insertion. The promoter contains putative binding sites for transcription factors (TF) that are typically involved in stress responses. The deduced amino acid sequences contain the classic domains, binding sites for allosteric effectors and potential reversible phosphorylation residues. Protein modeling indicates a homotetramer with highly conserved structure. The effect of hypoxia for 6 and 12 h showed tissue-specific patterns, with higher expression, enzyme activity and lactate in muscle, but higher glucose in hepatopancreas. Changes in response to hypoxia were detected at 12 h in expression with induction in muscle and reduction in hepatopancreas, while enzyme activity was maintained, and glucose and lactate decreased. These results show rapid changes in expression and metabolites, while enzyme activity was maintained to cope with short-term hypoxia.

Skeletal muscle fibre type and enzymatic activity in adult offspring following placental and peripheral malaria exposure in foetal life.

Maternal malaria may restrict foetal growth. Impaired utero-placental blood flow due to malaria infection may cause hypoxia-induced altered skeletal muscle fibre type distribution in the offspring, which may contribute to insulin resistance and impaired glucose metabolism. This study assessed muscle fibre distribution 20 years after placental and/or peripheral in-utero malaria exposure compared to no exposure, i.e., PPM+, PM+, and M-, respectively. We traced 101 men and women offspring of mothers who participated in a malaria chemosuppression study in Muheza, Tanzania. Of 76 eligible participants, 50 individuals (29 men and 21 women) had skeletal muscle biopsy taken from m. vastus lateralis in the right leg. As previously reported, fasting and 30 min post-oral glucose challenge plasma glucose values were higher, and insulin secretion disposition index was lower, in the PPM+ group. Aerobic capacity (fitness) was estimated by an indirect VO2max test on a stationary bicycle. Muscle fibre sub-type (myosin heavy chain, MHC) distribution was analysed, as were muscle enzyme activities (citrate synthase (CS), 3-hydroxyacyl-CoA dehydrogenase, myophosphorylase, phosphofructokinase, lactate dehydrogenase, and creatine kinase activities. Between-group analyses were adjusted for MHC-I %. No differences in aerobic capacity were found between groups. Despite subtle elevations of plasma glucose levels in the PPM+ group, there was no difference in MHC sub-types or muscle enzymatic activities between the malaria-exposed and non-exposed groups. The current study did not show differences in MHC towards glycolytic sub-types or enzymatic activity across the sub-groups. The results support the notion of the mild elevations of plasma glucose levels in people exposed to placental malaria in pregnancy being due to compromised pancreatic insulin secretion rather than insulin resistance.

The effects of size on exhaustive exercise and recovery in a marine sportfish, the red drum (Sciaenops ocellatus).

Recreational angling is an economically important activity in many communities around the world. One conservation strategy adopted to offset the population-level consequences of recreational angling is "catch-and-release" (CAR), which is the act of returning fish to the environment following an angling event. While an expansive literature has helped to generalize CAR best practices, species-specific validation of recovery profiles remains a crucial component of species-specific angling guidance. This study sought to define the injury and recovery profiles in the plasma and white muscle following exhaustive exercise in two size classes of a common Gulf of Mexico sportfish, the red drum (Sciaenops ocellatus). The two sizes included a "small" (20-30cm) and "slot" size (51-74cm), the latter of which is a common angling target. Both size classes showed a characteristic injury profile that consisted of significantly elevated muscle and plasma lactate, plasma osmolality and haematocrit, as well as decreased muscle ATP and phosphocreatine, and lowered plasma and muscle pH. In small fish, muscle metabolites returned to control values by 1h post-exercise and plasma metabolites returned to control between 3 and 6h post-exercise. In contrast, slot sized fish had recovery periods of ≥3h for all metabolites. The maximum injury effect size was also greater in the slot size class. These data suggest that while red drum conform to typical patterns of post-exercise recovery, larger trophy-sized fish may be more at risk to the ancillary effects of exhaustive exercise owing to greater exercise injury and slower recovery rates.

Aluminum induces a stress response in zebrafish gills by influencing metabolic parameters, morphology, and redox homeostasis

Environmental air pollution and resulting acid rain have the effect of increasing aluminum levels in water bodies. We studied the effects of aluminum on fish gills, the tissue most exposed to aluminum, using zebrafish as an experimental model. Adult zebrafish were exposed to an aluminum concentration found in polluted environments (11 mg/L) for 10, 15 and 20 days and the effects on gill morphology, redox homeostasis (ROS content, NADPH oxidase, NOX, activity, oxidative damage, antioxidant enzymes, total antioxidant capacity, in vitro susceptibility to oxidants) and on behavioural and metabolic parameters (routine respiratory oxygen consumption rMO2, tail-beating frequency, cytochrome oxidase activity and muscle lactate content) were evaluated.Exposure to aluminum affects branchial histology, inducing alterations in primary and secondary lamellae and redox homeostasis, modifying ROS levels, NOX activity, lipid and protein oxidative damage, antioxidant enzymes, and total antioxidant capacities, and increases rMO2. The effects exhibited a time-dependent behaviour, suggesting the activation of an adaptive response. These changes are associated with a transition of muscle metabolism from aerobic to anaerobic, as suggested by the increase in muscle lactate content, which is probably functional to preserve locomotor performance.Overall, the results here reported provide new insights into the toxicity mechanisms of Al exposure on gill tissue and the subsequent adaptive response of aquatic species.

Association Between Pretreatment Skeletal Muscle and Outcomes After CAR T-Cell Therapy.

The purpose of this study was to examine the association between baseline skeletal muscle measurements, acute toxicity (immune effector cell-associated neurotoxicity syndrome [ICANS], cytokine release syndrome), and treatment efficacy in patients undergoing CAR T-cell therapy for B-lineage lymphoma. Skeletal muscle measurements were obtained from automated CT measurements in 226 consecutive patients who received CAR T-cell therapy between 2015 and 2021. The Kaplan-Meier method was used to examine progression-free survival (PFS) and overall survival (OS) at 1-year. Multivariable regression was used to calculate the hazard ratio (HR) with 95% confidence intervals, adjusted for covariates. The median age of the cohort was 63.1 years (range, 18.5-82.4 years), and most patients were male (66%) and had primary refractory disease (58%). Patients with abnormally low skeletal muscle at baseline were at greater risk of ICANS (HR, 1.74; 95% CI, 1.05-2.87) and had longer length of hospitalization (mean 27.7 vs 22.9 days; P<.05) compared with those with normal muscle mass. Abnormal skeletal muscle was independently associated with risk of disease progression (HR, 1.70; 95% CI, 1.11-2.57) and worse survival (HR, 2.44; 95% CI, 1.49-4.00) at 1 year compared with normal skeletal muscle. Individuals who had abnormal skeletal muscle and high lactate dehydrogenase (LDH) levels at baseline had poor 1-year PFS (17%) and OS (12%) compared with those with normal skeletal muscle and LDH levels (72% and 82%, respectively; P<.001). Patients who had abnormal skeletal muscle and LDH levels had a 5-fold risk (HR, 5.34; 95% CI, 2.97-9.62) of disease progression and a 10-fold risk (HR, 9.73; 95% CI, 4.81-19.70) of death (reference: normal skeletal muscle, normal LDH), independent of prior lines of therapy, extent of residual disease at time of CAR T-cell therapy, functional status, or product. This information can be used for risk stratification prior to CAR T-cell therapy or to implement prehabilitation and nutritional optimization before lymphodepletion as well as thereafter. These efforts will be complementary to ongoing efforts toward sustained efficacy after CAR T-cell therapy.

Acute effect of different blood flow restriction protocols on muscle damage

The aim of this study is to examine the acute effect of different blood flow restriction (BFR) protocols on muscle damage. Thirty (age 19.77±1.30 years) healthy young men were included in the study. Participants were randomly divided into three groups: Experiment 1 (continuous BFR+ barbell squat, n=10), Experiment 2 (intermittent BFR + barbell squat, n=10), and Control (only barbell squats without BFR, n=10). In 80% of their 1RMs, they performed barbell squat exercises for a total of six sets, with two repetitions in each set and a 3-minute rest interval between sets. For markers of muscle damage creatine kinase (CK), lactate dehydrogenase (LDH), aspartate transaminase (AST), and alanine transaminase (ALT), blood was drawn from the individuals twice before and immediately after the exercise. Analysis of variance in repeated measures (Repeated Measures ANOVA) test was used to analyze the data. In statistical analysis, the level of significance was accepted as p

Utilization of valorized cassava leaf meal as an alternative feedstuff to defatted soybean meal in feed for rohu, Labeo rohita fingerlings

Growth and physiological responses of rohu to substitution of defatted soybean meal (DSBM) by cassava leaf protein concentrate (CLPC) was studied. Three clusters of rohu fingerlings (average weight, 1.90 ± 0.05 g) were fed similar diets (300.00 ± 2.70 g/kg crude protein and 17.54 ± 0.06 kJ/g gross energy) in which 300 g/kg DSBM was replaced by 0, 33, 66 and 100 % CLPC for 60 days. Growth was not influenced by treatment; however, feed conversion increased linearly (P = 0.038). Insulin-like growth factor (IGF)-I gene expression was not altered by treatment whereas its binding protein (IGFBP-I) tended towards linear up-regulation (P = 0.052). Liver catalase and superoxide dismutase activities increased remarkably (P < 0.05) consequent of dietary CLPC. Hepatic and muscle malate dehydrogenase, lactate dehydrogenase, aspartate and alanine aminotransferases of the fish showed no distinctive variation (P > 0.05). Based on observed results, we concluded that 66 % dietary DSBM can be substituted by CLPC without impairing growth, feed utilization and intermediary metabolism of rohu.

Acute effects of blood flow restriction with whole-body vibration on sprint, muscle activation and metabolic accumulation in male sprinters.

Purpose: The aim of this study was to explore the acute effects of Blood Flow Restriction Training (BFRT), Whole-Body Vibration (WBV), and BFRT + WBV on the 20m sprint, muscle activation, and metabolic accumulation in male sprinters. Method: Sixteen male sprinters randomly performed BFRT, WBV, or BFRT + WBV interventions with 72h intervals. Electromyography (EMG) signals were collected before and during interventions. Fingertip blood was taken before, immediately after, and 15min after the intervention. 20m sprint was performed before and 3min after the intervention. Results: 1) 0-10m and 0-20m sprint performance were significantly improved after WBV and BFRT + WBV interventions (p < 0.05), 0-20m sprint performance was significantly improved after all three interventions (p < 0.05), 2) After BFRT + WBV intervention, the EMG amplitude of the vastus lateralis and soleus were significantly improved. Greater increases in EMG activity of the tibialis anterior muscle (p < 0.05)and blood lactate (p < 0.05)were observed following BFRT intervention compared to BFRT + WBV intervention. Conclusion: For sprint performance, BFRT and WBV had similar post-activation enhancement effects to BFRT + WBV, and the metabolic accumulation immediately following the BFRT were higher than that following BFRT + WBV in male sprinters.

Computational Analysis of the Ligand-Binding Sites of the Molecular Chaperone OppA from Yersinia pseudotuberculosis.

The function of chaperones is to correct or degrade misfolded proteins inside the cell. Classic molecular chaperones such as GroEL and DnaK have not been found in the periplasm of Yersinia pseudotuberculosis. Some periplasmic substrate-binding proteins could be bifunctional, such as OppA. Using bioinformatic tools, we try to elucidate the nature of the interactions between OppA and ligands from four proteins with different oligomeric states. Using the crystal structure of the proteins Mal12 alpha-glucosidase from Saccharomyces cerevisiae S288C, LDH rabbit muscle lactate dehydrogenase, EcoRI endonuclease from Escherichia coli and THG Geotrichum candidum lipase, a hundred models were obtained in total, including five different ligands from each enzyme with five conformations of each ligand. The best values for Mal12 stem from ligands 4 and 5, with conformation 5 for both; for LDH, ligands 1 and 4, with conformations 2 and 4, respectively; for EcoRI, ligands 3 and 5, with conformation 1 for both; and for THG, ligands 2 and 3, with conformation 1 for both. The interactions were analyzed with LigProt, and the length of the hydrogen bridges has an average of 2.8 to 3.0 Å. The interaction within the OppA pocket is energetically favored due to the formation of hydrogen bonds both of OppA and of the selected enzymes. The Asp 419 residue is important in these junctions.

Nutritional and functional quality, and oxidative status of Pampa Rocha pork in an outdoor vs. a confined system: Doctoral thesis abstract

The chemical, nutritional and functional composition of Pampa Rocha pork, produced in two systems, outdoors with pastures and deep bed, was studied. The animals in the outdoor system showed improvements in some carcass and meat parameters. In both systems, the meat was adequate from the nutritional and technological point of view, for consumption and processing, fresh or preserved. Meat from outdoor had a lower pH, was darker, and had higher drip loss. Longissimus longissimus thoracis had a higher pH, and drip loss, was less red and lighter than psoas major, regardless of the production system. The aged meat presented a stable pH, but it was redder and yellower, and with a higher drip loss than fresh meat. Muscle glycogen and lactate were not affected by the production system, the type of muscle or the sex of the animals. The oxidative stability of lipids and proteins was similar for both systems, but it depended on the type of muscle, with the psoas major being a more fragile muscle against oxidation. The fatty acid profile was similar in both systems, but the psoas major had a higher lipid content than the longissimus. The latter, produced outdoors, presents a moderate improvement in the fatty acid profile, particularly with alpha-linolenic acid (C18:3n-3), and a lower n-6/n-3 ratio. The production system had an impact on the iron content, particularly bioavailable iron, with the heme iron/total iron ratio being higher in meat produced on pastures, considering the longissimus and psoas muscles, and the hindquarters, gluteus medius, semitendinosus, biceps femoral, and quadriceps femoris. In this thesis, knowledge was generated about the particularity of each muscle, in terms of its nutritional and technological attributes, regardless of the productive system. The outdoor system presents some advantages that enhance the genetic type in an environment that may interest consumers with particular requirements.

THE ACTIVITY OF LACTATE DEHYDROGENASE AND CONTENT OF LACTATE AND PYRUVATE IN THE SCELETAL MUSCLE OF RAT UNDER CONDITIONS OF TOXIC INJURY WITH ACETAMINOPHEN

The aim of this work was to study the activity of lactate dehydrogenase, the content of lactate, pyruvate and the lactate/pyruvate ratio in skeletal muscles of rats under the conditions of toxic damage with acetaminophen against the background of protein deficiency. Lactate dehydrogenase activity was determined by a kinetic method based on the reduction of pyruvate in the presence of NADH, lactate content – spectrophotometrically at λ 390 nm by the accumulation of iron lactate, pyruvate content – spectrophotometrically at λ 440 nm by the formation of hydrazone during the interaction of pyruvic acid with 2,4 dinitrophenylhydrazine. The study was conducted on 4 groups of animals: Group I - control animals (K); II – rats kept on a low-protein diet (LPR); III – animals with acute toxic damage by acetaminophen (TD); IV – rats, which were simulated acute toxic damage with acetaminophen (LPR/TD) against the background of a low-protein diet. It was established that under the conditions of consumption of a low-protein diet, there are no significant changes in the activity of lactate dehydrogenase and the content of lactate, while at the same time, under the studied conditions, the content of pyruvate in the cytosol of skeletal muscles decreases, which probably indicates the transformation of pyruvate in other metabolic pathways. Under the conditions of toxic damage by acetaminophen, regardless of the provision of protein in the diet, an increase in the activity of lactate dehydrogenase is accompanied by a pronounced accumulation of lactate against the background of a decrease in the content of pyruvate, which may indicate the activation of anaerobic processes of ATP formation. The results of the studies showed an increase in the lactate/pyruvate ratio in the cytosol of skeletal muscles of rats with acetaminophen-induced toxic damage against the background of dietary protein deficiency. The obtained results regarding the activity of lactate dehydrogenase, the content of lactate and pyruvate in the skeletal muscles of rats under conditions of toxic damage against the background of alimentary protein deficiency indicate the activation of anaerobic mechanisms of energy supply and can be considered as adaptive reactions aimed at maintaining energy homeostasis.

Resilience and phenotypic plasticity of Arctic char (Salvelinus alpinus) facing cyclic hypoxia: insights into growth, energy stores and hepatic metabolism.

Arctic char (Salvelinus alpinus) is facing the decline of its southernmost populations due to several factors including rising temperatures and eutrophication. These conditions are also conducive to episodes of cyclic hypoxia, another possible threat to this species. In fact, lack of oxygen and reoxygenation can both have serious consequences on fish as a result of altered ATP balance and an elevated risk of oxidative burst. Thus, fish must adjust their phenotype to survive and equilibrate their energetic budget. However, their energy allocation strategy could imply a reduction in growth which could be deleterious for their fitness. Although the impact of cyclic hypoxia is a major issue for ecosystems and fisheries worldwide, our knowledge on how salmonid deal with high oxygen fluctuations remains limited. Our objective was to characterize the effects of cyclic hypoxia on growth and metabolism in Arctic char. We monitored growth parameters (specific growth rate, condition factor), hepatosomatic and visceral indexes, relative heart mass and hematocrit of Arctic char exposed to 30days of cyclic hypoxia. We also measured the hepatic protein synthesis rate, hepatic triglycerides as well as muscle glucose, glycogen and lactate and quantified hepatic metabolites during this treatment. The first days of cyclic hypoxia slightly reduce growth performance with a downward trend in specific growth rate in mass and condition factor variation compared to the control group. This acute exposure also induced a profound metabolome reorganization in the liver with an alteration of amino acid, carbohydrate and lipid metabolisms. However, fish rebalanced their metabolic activities and successfully maintained their growth and energetic reserves after 1month of cyclic hypoxia. These results demonstrate the impressive ability of Arctic char to cope with its changing environment but also highlight a certain vulnerability of this species during the first days of a cyclic hypoxia event.

Population variability in thermal performance of pre-spawning adult Chinook salmon.

Climate change is causing large declines in many Pacific salmon populations. In particular, warm rivers are associated with high levels of premature mortality in migrating adults. The Fraser River watershed in British Columbia, Canada, supports some of the largest Chinook salmon (Oncorhynchus tshawytscha) runs in the world. However, the Fraser River is warming at a rate that threatens these populations at critical freshwater life stages. A growing body of literature suggests salmonids are locally adapted to their thermal migratory experience, and thus, population-specific thermal performance information can aid in management decisions. We compared the thermal performance of pre-spawning adult Chinook salmon from two populations, a coastal fall-run from the Chilliwack River (125km cooler migration) and an interior summer-run from the Shuswap River (565km warmer migration). We acutely exposed fish to temperatures reflecting current (12°C, 18°C) and future projected temperatures (21°C, 24°C) in the Fraser River and assessed survival, aerobic capacity (resting and maximum metabolic rates, absolute aerobic scope (AAS), muscle and ventricle citrate synthase), anaerobic capacity (muscle and ventricle lactate dehydrogenase) and recovery capacity (post-exercise metabolism, blood physiology, tissue lactate). Chilliwack Chinook salmon performed worse at high temperatures, indicated by elevated mortality, reduced breadth in AAS, enhanced plasma lactate and potassium levels and elevated tissue lactate concentrations compared with Shuswap Chinook salmon. At water temperatures exceeding the upper pejus temperatures (Tpejus, defined here as 80% of maximum AAS) of Chilliwack (18.7°C) and Shuswap (20.2°C) Chinook salmon populations, physiological performance will decline and affect migration and survival to spawn. Our results reveal population differences in pre-spawning Chinook salmon performance across scales of biological organization at ecologically relevant temperatures. Given the rapid warming of rivers, we show that it is critical to consider the intra-specific variation in thermal physiology to assist in the conservation and management of Pacific salmon.

O efeito da baixa temperatura na regeneração esportiva

Abstract Introduction Intense physical activity and increased exercise significantly reduce the body's adaptive capacity, negatively affect the recovery processes of athletes, and can significantly impair athletic performance. Objective To identify how low temperatures can affect the regenerative processes in athletes, assess the effectiveness and feasibility of cold therapy in sports, and identify the key parameters that determine the effectiveness of the stated recovery method. Methods A systematic review of studies related to the use of cold therapy in sports guided by the Cochrane Handbook for Systematic Reviews of Interventions, and reported through the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. The scientific material was selected by finding keywords and phrases, including “the effect of cold on athletes”, “athletes’ recovery”, “cold therapy”, etc. Following the selection criteria, only 30 studies were included. Results Cold exposure has significant benefits for sports regeneration, including pain relief (100%), inflammation reduction (93%), and restoration of sprint capabilities (89%). However, its impact on muscle strength (33%), endurance (11%), and lactate reduction (8%) is more limited. It moderately improves the psycho-emotional state (65-75%). Conclusion The use of low temperatures in sports has a beneficial effect on the recovery of sports performance for at least 24 hours after intense physical activity (training).

Red ginseng extract improves skeletal muscle energy metabolism and mitochondrial function in chronic fatigue mice.

Background: Skeletal muscles are organs with high energy requirements, especially during vigorous exercise. Adequate mitochondrial function is essential to meet the high energy needs of skeletal muscle cells. Recent studies have reported that red ginseng can significantly improve chronic fatigue; however, the specific mechanism of action is still not clear. Methods: A chronic fatigue syndrome mouse model was developed using C57BL/6J mice through long-term compound stimulation of stress factors. Following this, the animals were orally administered 200, 400, or 600mg/kg red ginseng extracts for 28 days. Skeletal muscle lactate acid, serum lactate dehydrogenase, urea concentrations, ATP level, mitochondrial membrane potential, activities of Na+-K+-ATPase and cytochrome c oxidase were determined using assay kits or an automatic biochemical analyser detection system. Skeletal muscle mitochondria morphology was observed using electron microscopy and the expression of p-AMPK, PGC-1α, ACO2 and complex I in skeletal muscle protein was determined by western blotting. Results: Oral administration of 400 or 600mg/kg red ginseng extract in mice with chronic fatigue reduced lactic acid, lactate dehydrogenase and urea, rescued the density and morphology of skeletal muscle mitochondria, increased the activities of Na+-K+-ATPase and cytochrome c oxidase, and activated the AMPK/PGC-1α cascade pathway, resulting in improved skeletal muscle mitochondrial function by restoring ATP level, mitochondrial membrane potential, complex I and mitochondrial biogenesis. Conclusion: The anti-fatigue effects of red ginseng are partly related to its potent mitochondrial improving activity, including decreasing mitochondrial swelling and mitochondrial membrane permeability, increasing mitochondrial biogenesis, thus ameliorating mitochondrial dysfunction.

Effects of Salinity and Dissolved Oxygen Concentration on the Tail-Flip Speed and Physiologic Response of Whiteleg Shrimp, Litopenaeus vannamei

The swimming ability of shrimp is important for their survival and growth, which directly affects their avoidance of enemies and uncomfortable environment, search and capture of food, reproductive behavior, and distribution. The knowledge concerning the swimming ability of shrimp can be widely used in the conservation of fishery resources, improving capture efficiency and stock enhancement. As one of the edible marine organisms, Litopenaeus vannamei is a traditional fishery resource and an important economic aquaculture species in China. Dissolved oxygen (DO) concentration and salinity are considered to play crucial roles in the swimming ability of L. vannamei. The tail-flip speed (Stf) of whiteleg shrimp L. vannamei (79.90 ± 0.41 mm, 5.76 ± 0.10 g) that were exposed to various salinities (20‰, 25‰, 30‰, 35‰, and 40‰) and DO concentrations (1.9, 3.8, 6.8, and 13.6 mg/L) was determined under laboratory conditions. Metabolite concentrations in the hemolymph, hepatopancreas, and abdominal muscles were measured before and after tail-flip fatigue to evaluate the physiologic effects of fatigue in L. vannamei. The results showed that salinity and DO significantly affected the Stf of L. vannamei. The Stf increased and subsequently decreased with the increase in salinity from 20‰ to 40‰. The relationship between Stf and salinity (s, ‰) can be expressed by the quadratic model as Stf = −0.2386s2 + 15.528s − 145.12, R2 = 0.9693. The optimum salinity and corresponding maximum Stf were 32.54‰ and 107.52 cm/s, respectively. The Stf increased as the DO concentration increased from 1.9 mg/L to 13.6 mg/L. The relationship between Stf and DO (mg/L) can be expressed by the power model as Stf = 75.621 DO0.1753, R2 = 0.9981. The different salinities and DO concentrations directly affected the physiology of the shrimp, inducing changes in hepatopancreas total protein, plasma total protein, abdominal muscle lactate, plasma lactate, plasma glucose, hepatopancreas glycogen, and abdominal muscle glycogen concentration. Fatigue from tail-flip led to severe loss of hepatopancreas glycogen under 20‰ salinity and plasma glucose under 25‰, 30‰, and 35‰ salinity. The triglyceride and lactate in the plasma concentration increased significantly in a range of salinities. In the DO concentration experiment, fatigue from tail-flip led to a severe loss of plasma glucose under 1.9 mg/L and 3.8 mg/L DO concentrations. The plasma lactate concentration increased significantly in all DO groups. The results suggested that the inappropriate salinity and DO significantly limited the tail-flip speed of shrimp, which was due to the accumulation of metabolites. The proper salinity and DO accelerated the elimination of metabolites, reduced the energy consumption of shrimp, and thus, improved the exercise ability of shrimp. This conclusion is of particular value in evaluating the swimming ability of shrimp and understanding its ecological processes to improve capture and rearing techniques.