The influence of acute resistance exercise on cyclooxygenase-1 and -2 activity and protein levels in human skeletal muscle

2013 ◽  
Vol 305 (1) ◽  
pp. R24-R30 ◽  
Author(s):  
Chad C. Carroll ◽  
Devin T. O'Connor ◽  
Robert Steinmeyer ◽  
Jonathon D. Del Mundo ◽  
David R. McMullan ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Resistance Exercise ◽  
Total Protein ◽  
Human Skeletal Muscle ◽  
Vastus Lateralis ◽  
Knee Extensor ◽  
Protein Levels ◽  
Cyclooxygenase 1 ◽  
Cox 2 ◽  
Cox 1

This study evaluated the activity and content of cyclooxygenase (COX)-1 and -2 in response to acute resistance exercise (RE) in human skeletal muscle. Previous work suggests that COX-1, but not COX-2, is the primary COX isoform elevated with resistance exercise in human skeletal muscle. COX activity, however, has not been assessed after resistance exercise in humans. It was hypothesized that RE would increase COX-1 but not COX-2 activity. Muscle biopsies were taken from the vastus lateralis of nine young men (25 ± 1 yr) at baseline (preexercise), 4, and 24 h after a single bout of knee extensor RE (three sets of 10 repetitions at 70% of maximum). Tissue lysate was assayed for COX-1 and COX-2 activity. COX-1 and COX-2 protein levels were measured via Western blot analysis. COX-1 activity increased at 4 h ( P < 0.05) compared with preexercise, but returned to baseline at 24 h (PRE: 60 ± 10, 4 h: 106 ± 22, 24 h: 72 ± 8 nmol PGH2·g total protein−1·min−1). COX-2 activity was elevated at 4 and 24 h after RE ( P < 0.05, PRE: 51 ± 7, 4 h: 100 ± 19, 24 h: 98 ± 14 nmol PGH2·g total protein−1·min−1). The protein level of COX-1 was not altered ( P > 0.05) with acute RE. In contrast, COX-2 protein levels were nearly 3-fold greater ( P > 0.05) at 4 h and 5-fold greater ( P = 0.06) at 24 h, compared with preexercise. In conclusion, COX-1 activity increases transiently with exercise independent of COX-1 protein levels. In contrast, both COX-2 activity and protein levels were elevated with exercise, and this elevation persisted to at least 24 h after RE.

scholarly journals Effect of a cyclooxygenase-2 inhibitor on postexercise muscle protein synthesis in humans

2010 ◽  
Vol 298 (2) ◽  
pp. E354-E361 ◽  
Author(s):  
Nicholas A. Burd ◽  
Jared M. Dickinson ◽  
Jennifer K. LeMoine ◽  
Chad C. Carroll ◽  
Bridget E. Sullivan ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Resistance Exercise ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Vastus Lateralis ◽  
Constant Infusion ◽  
Synthesis Rate ◽  
Cox 2 ◽  
Cox 1

Nonselective blockade of the cyclooxygenase (COX) enzymes in skeletal muscle eliminates the normal increase in muscle protein synthesis following resistance exercise. The current study tested the hypothesis that this COX-mediated increase in postexercise muscle protein synthesis is regulated specifically by the COX-2 isoform. Sixteen males (23 ± 1 yr) were randomly assigned to one of two groups that received three doses of either a selective COX-2 inhibitor (celecoxib; 200 mg/dose, 600 mg total) or a placebo in double-blind fashion during the 24 h following a single bout of knee extensor resistance exercise. At rest and 24 h postexercise, skeletal muscle protein fractional synthesis rate (FSR) was measured using a primed constant infusion of [2H5]phenylalanine coupled with muscle biopsies of the vastus lateralis, and measurements were made of mRNA and protein expression of COX-1 and COX-2. Mixed muscle protein FSR in response to exercise ( P < 0.05) was not suppressed by the COX-2 inhibitor (0.056 ± 0.004 to 0.108 ± 0.014%/h) compared with placebo (0.074 ± 0.004 to 0.091 ± 0.005%/h), nor was there any difference ( P > 0.05) between the placebo and COX-2 inhibitor postexercise when controlling for resting FSR. The COX-2 inhibitor did not influence COX-1 mRNA, COX-1 protein, or COX-2 protein levels, whereas it did increase ( P < 0.05) COX-2 mRNA (3.0 ± 0.9-fold) compared with placebo (1.3 ± 0.3-fold). It appears that the elimination of the postexercise muscle protein synthesis response by nonselective COX inhibitors is not solely due to COX-2 isoform blockade. Furthermore, the current data suggest that the COX-1 enzyme is likely the main isoform responsible for the COX-mediated increase in muscle protein synthesis following resistance exercise in humans.

Influence of muscle glycogen availability on ERK1/2 and Akt signaling after resistance exercise in human skeletal muscle

2005 ◽  
Vol 99 (3) ◽  
pp. 950-956 ◽  
Author(s):  
Andrew Creer ◽  
Philip Gallagher ◽  
Dustin Slivka ◽  
Bozena Jemiolo ◽  
William Fink ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Resistance Exercise ◽  
Muscle Glycogen ◽  
Human Skeletal Muscle ◽  
Glycogen Content ◽  
Vastus Lateralis ◽  
Akt Signaling ◽  
Cellular Growth ◽  
Muscle Glycogen Content ◽  
Ribosomal S6 Kinase

Two pathways that have been implicated for cellular growth and development in response to muscle contraction are the extracellular signal-regulated kinase (ERK1/2) and Akt signaling pathways. Although these pathways are readily stimulated after exercise, little is known about how nutritional status may affect stimulation of these pathways in response to resistance exercise in human skeletal muscle. To investigate this, experienced cyclists performed 30 repetitions of knee extension exercise at 70% of one repetition maximum after a low (2%) or high (77%) carbohydrate (LCHO or HCHO) diet, which resulted in low or high (∼174 or ∼591 mmol/kg dry wt) preexercise muscle glycogen content. Muscle biopsies were taken from the vastus lateralis before, ∼20 s after, and 10 min after exercise. ERK1/2 and p90 ribosomal S6 kinase phosphorylation increased ( P ≤ 0.05) 10 min after exercise, regardless of muscle glycogen availability. Akt phosphorylation was elevated ( P < 0.05) 10 min after exercise in the HCHO trial but was unaffected after exercise in the LCHO trial. Mammalian target of rapamycin phosphorylation was similar to that of Akt during each trial; however, change or lack of change was not significant. In conclusion, the ERK1/2 pathway appears to be unaffected by muscle glycogen content. However, muscle glycogen availability appears to contribute to regulation of the Akt pathway, which may influence cellular growth and adaptation in response to resistance exercise in a low-glycogen state.

Expression of titin-linked putative mechanosensing proteins in skeletal muscle after power resistance exercise in resistance-trained men

2020 ◽  
Author(s):  
Stefan G. Wette ◽  
Nigel P. Birch ◽  
Matthias Soop ◽  
Martina Zügel ◽  
Robyn M. Murphy ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Creatine Kinase ◽  
Resistance Exercise ◽  
Vastus Lateralis ◽  
Cytoskeletal Proteins ◽  
Muscle Sample ◽  
Post Exercise ◽  
Protein Levels ◽  
Ankyrin Repeat Proteins ◽  
Muscle Remodeling

Little is known about the molecular responses to power resistance exercise that lead to skeletal muscle remodeling and enhanced athletic performance. We assessed the expression of titin-linked putative mechanosensing proteins implicated in muscle remodeling: muscle ankyrin repeat proteins (Ankrd1, Ankrd2 and Ankrd23), muscle-LIM proteins (MLP), muscle RING-finger protein-1 (MuRF-1), and associated myogenic proteins (MyoD1, myogenin, and myostatin) in skeletal muscle in response to power resistance exercise with or without a post-exercise meal, in fed, resistance-trained men. A muscle sample was obtained from the vastus lateralis of seven healthy men on separate days, 3h after 90 min of rest (Rest) or power resistance exercise with (Ex+Meal) or without (Ex) a post-exercise meal, to quantify mRNA and protein levels. The levels of phosphorylated HSP27 (pHSP27-Ser15) and cytoskeletal proteins in muscle and creatine kinase activity in serum were also assessed. The exercise increased (P≤0.05) pHSP27-Ser15 (~6-fold) and creatine kinase (~50%), whereas cytoskeletal protein levels were unchanged (P>0.05). Ankrd1 (~15-fold) and MLP (~2-fold) mRNA increased, whereas Ankrd2, Ankrd23, MuRF-1, MyoD1, and myostatin mRNA were unchanged. Ankrd1 (~3-fold, Ex) and MLPb (~20-fold, Ex+Meal) protein increased, but MLPa, Ankrd2, Ankrd23, and the myogenic proteins were unchanged. The post-exercise meal did not affect the responses observed. Power resistance exercise, as performed in practice, induced subtle early responses in the expression of MLP and Ankrd1, yet had little effect on the other proteins investigated. These findings suggest possible roles for MLP and Ankrd1 in the remodeling of skeletal muscle in individuals who regularly perform this type of exercise.

scholarly journals Prostaglandin E2/cyclooxygenase pathway in human skeletal muscle: influence of muscle fiber type and age

2016 ◽  
Vol 120 (5) ◽  
pp. 546-551 ◽  
Author(s):  
Sophia Z. Liu ◽  
Bozena Jemiolo ◽  
Kaleen M. Lavin ◽  
Bridget E. Lester ◽  
Scott W. Trappe ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Fiber ◽  
Human Skeletal Muscle ◽  
Muscle Protein ◽  
Vastus Lateralis ◽  
Production Capacity ◽  
Prostaglandin E ◽  
Type I ◽  
Men And Women ◽  
Cox 1

Prostaglandin E2 (PGE2) produced by the cyclooxygenase (COX) pathway regulates skeletal muscle protein turnover and exercise training adaptations. The purpose of this study was twofold: 1) define the PGE2/COX pathway enzymes and receptors in human skeletal muscle, with a focus on type I and II muscle fibers; and 2) examine the influence of aging on this pathway. Muscle biopsies were obtained from the soleus (primarily type I fibers) and vastus lateralis (proportionally more type II fibers than soleus) of young men and women ( n = 8; 26 ± 2 yr), and from the vastus lateralis of young ( n = 8; 25 ± 1 yr) and old ( n = 12; 79 ± 2 yr) men and women. PGE2/COX pathway proteins [COX enzymes (COX-1 and COX-2), PGE2 synthases (cPGES, mPGES-1, and mPGES-2), and PGE2 receptors (EP1, EP2, EP3, and EP4)] were quantified via Western blot. COX-1, cPGES, mPGES-2, and all four PGE2 receptors were detected in all skeletal muscle samples examined. COX-1 ( P < 0.1) and mPGES-2 were ∼20% higher, while EP3 was 99% higher and EP4 57% lower in soleus compared with vastus lateralis ( P < 0.05). Aging did not change the level of skeletal muscle COX-1, while cPGES increased 45% and EP1 ( P < 0.1), EP3, and EP4 decreased ∼33% ( P < 0.05). In summary, PGE2 production capacity and receptor levels are different in human skeletal muscles with markedly different type I and II muscle fiber composition. In aging skeletal muscle, PGE2 production capacity is elevated and receptor levels are downregulated. These findings have implications for understanding the regulation of skeletal muscle adaptations to exercise and aging by the PGE2/COX pathway and related inhibitors.

Acute exercise and GLUT4 expression in human skeletal muscle: influence of exercise intensity

2006 ◽  
Vol 101 (3) ◽  
pp. 934-937 ◽  
Author(s):  
Giorgos N. Kraniou ◽  
David Cameron-Smith ◽  
Mark Hargreaves
Keyword(s):  
Skeletal Muscle ◽  
Exercise Intensity ◽  
Muscle Glycogen ◽  
Human Skeletal Muscle ◽  
Acute Exercise ◽  
Vastus Lateralis ◽  
Dry Mass ◽  
Peak Oxygen Consumption ◽  
Protein Levels ◽  
Glut4 Expression

To examine the influence of exercise intensity on the increases in vastus lateralis GLUT4 mRNA and protein after exercise, six untrained men exercised for 60 min at 39 ± 3% peak oxygen consumption (V̇o2 peak) (Lo) or 27 ± 2 min at 83 ± 2% V̇o2 peak (Hi) in counterbalanced order. Preexercise muscle glycogen levels were not different between trials (Lo: 408 ± 35 mmol/kg dry mass; Hi: 420 ± 43 mmol/kg dry mass); however, postexercise levels were lower ( P < 0.05) in Hi (169 ± 18 mmol/kg dry mass) compared with Lo (262 ± 35 mmol/kg dry mass). Thus calculated muscle glycogen utilization was greater ( P < 0.05) in Hi (251 ± 24 mmol/kg) than in Lo (146 ± 34). Exercise resulted in similar increases in GLUT4 gene expression in both trials. GLUT4 mRNA was increased immediately at the end of exercise (∼2-fold; P < 0.05) and remained elevated after 3 h of postexercise recovery. When measured 3 h after exercise, total crude membrane GLUT4 protein levels were 106% higher in Lo (3.3 ± 0.7 vs. 1.6 ± 0.3 arbitrary units) and 61% higher in Hi (2.9 ± 0.5 vs. 1.8 ± 0.5 arbitrary units) relative to preexercise levels. A main effect for exercise was observed, with no significant differences between trials. In conclusion, exercise at ∼40 and ∼80% V̇o2 peak, with total work equal, increased GLUT4 mRNA and GLUT4 protein in human skeletal muscle to a similar extent, despite differences in exercise intensity and duration.

IL-6 and TNF-α expression in, and release from, contracting human skeletal muscle

2002 ◽  
Vol 283 (6) ◽  
pp. E1272-E1278 ◽  
Author(s):  
Adam Steensberg ◽  
Charlotte Keller ◽  
Rebecca L. Starkie ◽  
Takuya Osada ◽  
Mark A. Febbraio ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Human Skeletal Muscle ◽  
Vastus Lateralis ◽  
Knee Extensor ◽  
Tnf Α ◽  
Arterial Plasma ◽  
Exercise Muscle ◽  
Resting Muscle ◽  
Male Subjects ◽  
Net Release

The aim of the present study was to examine whether IL-6 and TNF-α are expressed in, and released from, human skeletal muscle during exercise. We hypothesized that the skeletal muscle will release IL-6, but not TNF-α, during exercise because of previous observations that TNF-α negatively affects glucose uptake in skeletal muscle. Six healthy, male subjects performed 180 min of two-legged knee-extensor exercise. Muscle samples were obtained from the vastus lateralis of one limb. In addition, blood samples were obtained from a femoral artery and vein. Plasma was analyzed for IL-6 and TNF-α. We detected both IL-6 and TNF-α mRNA in resting muscle samples, and whereas IL-6 increased ( P < 0.05) ∼100-fold throughout exercise, no significant increase in TNF-α mRNA was observed. Arterial plasma TNF-α did not increase during exercise. Furthermore, there was no net release of TNF-α either before or during exercise. In contrast, IL-6 increased throughout exercise in arterial plasma, and a net IL-6 release from the contracting limb was observed after 120 min of exercise ( P < 0.05).

scholarly journals PL - 041 Effects of power resistance exercise and feeding on the expression of putative mechanosensing proteins in skeletal muscle of resistance-trained men

2018 ◽  
Vol 1 (1) ◽  
Author(s):  
Stefan Wette ◽  
Heather K Smith ◽  
Graham D. Lamb ◽  
Robyn M Murphy
Keyword(s):  
Skeletal Muscle ◽  
Resistance Exercise ◽  
High Intensity ◽  
Muscle Function ◽  
Human Skeletal Muscle ◽  
Pearson Correlation ◽  
Exercise Session ◽  
Mrna Levels ◽  
Protein Levels ◽  
One Way Anova

Objective Power resistance exercise involves high intensity (load and velocity) dynamic muscular contractions and is frequently performed by athletes to enhance performance via improved muscle function. To investigate the remodelling processes that contribute to improved muscle function, we investigated the expression of putative mechanosensing genes implicated in this process (Kojic et al., 2011): titin-linked Muscle Ankyrin Repeat Protein (MARPs) family CARP, Ankrd 2 and DARP, and the Z-disc associated muscle-LIM protein (MLP) in healthy, resistance-trained men (n = 7) following 90 min of rest (Rest) or power resistance exercise, with (Ex + Meal) or without (Ex only) feeding during recovery. Methods Percutaneous needle biopsy samples were obtained from the vastus lateralis of resistance-trained males using local anesthetic (2% Xylocaine), 3 h after performing each of the three experimental trials on separate days. Previously, we presented results from this study showing that the mRNA levels of CARP (~15-fold) and MLP (~2.5-fold) were upregulated in human skeletal muscle 3 h post power resistance exercise (Wette et al., 2012). Based on these results, we performed protein analyses on the same muscle samples to determine the protein levels of all MARPs and MLP in whole muscle homogenates after Rest, Ex only and Ex + Meal. To assess whether the exercise elicited a stress response in these resistance-trained individuals, the level of phosphorylated heat shock protein 27 at serine 15 (pHSP27-Ser15) was measured at Rest and 3 h after Ex only and Ex + Meal. The levels of pHSP27-Ser15 are typically upregulated 3 h after eccentric exercise in human skeletal muscle (Frankenberg et al., 2014). Results The 90 min exercise session consisted of 180 intermittent muscular contractions at high intensity (70-96% maximal strength). Compared to Rest, there were ~5.8- and 12.6-fold increases in pHSP27-Ser15 levels at 3 h post Ex only and Ex + Meal (both P = 0.049, one-way ANOVA) respectively. CARP protein levels were elevated ~2.7-fold after Ex only (P = 0.049, one-way ANOVA) and ~7.6-fold after Ex + Meal (P = 0.326), due to markedly higher levels (6-40-fold) in three of the seven participants. Pearson correlation analysis revealed a significant positive correlation between the levels of pHSP27-Ser-15 and CARP protein (r = 0.56, P = 0.008). Ankrd 2, DARP and MLP protein levels were unchanged (all P > 0.05) following Ex only and Ex + Meal. Conclusions These findings indicate that CARP is highly responsive to increased mechanical loading because the protein levels in skeletal muscle can be substantially increased as early as 3 h after stressful resistance exercise. This suggests a specialised role for CARP protein during the early phases of muscle remodelling that occur as a consequence of performing high intensity resistance exercise.

scholarly journals Prior acetaminophen consumption impacts the early adaptive cellular response of human skeletal muscle to resistance exercise

2018 ◽  
Vol 124 (4) ◽  
pp. 1012-1024 ◽  
Author(s):  
Andrew C. D’Lugos ◽  
Shivam H. Patel ◽  
Jordan C. Ormsby ◽  
Donald P. Curtis ◽  
Christopher S. Fry ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Resistance Exercise ◽  
Mrna Expression ◽  
Adaptive Response ◽  
Cellular Response ◽  
Human Skeletal Muscle ◽  
Fiber Type ◽  
Vastus Lateralis ◽  
Muscle Adaptation ◽  
Cox Inhibitor

Resistance exercise (RE) is a powerful stimulus for skeletal muscle adaptation. Previous data demonstrate that cyclooxygenase (COX)-inhibiting drugs alter the cellular mechanisms regulating the adaptive response of skeletal muscle. The purpose of this study was to determine whether prior consumption of the COX inhibitor acetaminophen (APAP) alters the immediate adaptive cellular response in human skeletal muscle after RE. In a double-blinded, randomized, crossover design, healthy young men ( n = 8, 25 ± 1 yr) performed two trials of unilateral knee extension RE (8 sets, 10 reps, 65% max strength). Subjects ingested either APAP (1,000 mg/6 h) or placebo (PLA) for 24 h before RE (final dose consumed immediately after RE). Muscle biopsies (vastus lateralis) were collected at rest and 1 h and 3 h after exercise. Mammalian target of rapamycin (mTOR) complex 1 signaling was assessed through immunoblot and immunohistochemistry, and mRNA expression of myogenic genes was examined via RT-qPCR. At 1 h p-rpS6Ser240/244 was increased in both groups but to a greater extent in PLA. At 3 h p-S6K1Thr389 was elevated only in PLA. Furthermore, localization of mTOR to the lysosome (LAMP2) in myosin heavy chain (MHC) II fibers increased 3 h after exercise only in PLA. mTOR-LAMP2 colocalization in MHC I fibers was greater in PLA vs. APAP 1 h after exercise. Myostatin mRNA expression was reduced 1 h after exercise only in PLA. MYF6 mRNA expression was increased 1 h and 3 h after exercise only in APAP. APAP consumption appears to alter the early adaptive cellular response of skeletal muscle to RE. These findings further highlight the mechanisms through which COX-inhibiting drugs impact the adaptive response of skeletal muscle to exercise. NEW & NOTEWORTHY The extent to which the cellular reaction to acetaminophen impacts the mechanisms regulating the adaptive response of human skeletal muscle to resistance exercise is not well understood. Consumption of acetaminophen before resistance exercise appears to suppress the early response of mTORC1 activity to acute resistance exercise. These data also demonstrate, for the first time, that resistance exercise elicits fiber type-specific changes in the intracellular colocalization of mTOR with the lysosome in human skeletal muscle.

scholarly journals Transient transcriptional events in human skeletal muscle at the outset of concentric resistance exercise training

2014 ◽  
Vol 116 (1) ◽  
pp. 113-125 ◽  
Author(s):  
A. J. Murton ◽  
R. Billeter ◽  
F. B. Stephens ◽  
S. G. Des Etages ◽  
F. Graber ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Resistance Exercise ◽  
Muscle Damage ◽  
Time Course ◽  
Human Skeletal Muscle ◽  
Vastus Lateralis ◽  
Transcriptional Response ◽  
Physiological Adaptation ◽  
Multiple Time ◽  
Αb Crystallin

We sought to ascertain the time course of transcriptional events that occur in human skeletal muscle at the outset of resistance exercise (RE) training in RE naive individuals and determine whether the magnitude of response was associated with exercise-induced muscle damage. Sixteen RE naive men were recruited; eight underwent two sessions of 5 × 30 maximum isokinetic knee extensions (180°/s) separated by 48 h. Muscle biopsies of the vastus lateralis, obtained from different sites, were taken at baseline and 24 h after each exercise bout. Eight individuals acted as nonexercise controls with biopsies obtained at the same time intervals. Transcriptional changes were assessed by microarray and protein levels of heat shock protein (HSP) 27 and αB-crystallin in muscle cross sections by immunohistochemistry as a proxy measure of muscle damage. In control subjects, no probe sets were significantly altered (false discovery rate < 0.05), and HSP27 and αB-crystallin protein remained unchanged throughout the study. In exercised subjects, significant intersubject variability following the initial RE bout was observed in the muscle transcriptome, with greatest changes occurring in subjects with elevated HSP27 and αB-crystallin protein. Following the second bout, the transcriptome response was more consistent, revealing a cohort of probe sets associated with immune activation, the suppression of oxidative metabolism, and ubiquitination, as differentially regulated. The results reveal that the initial transcriptional response to RE is variable in RE naive volunteers, potentially associated with muscle damage and unlikely to reflect longer term adaptations to RE training. These results highlight the importance of considering multiple time points when determining the transcriptional response to RE and associated physiological adaptation.

Resistance exercise increases NF-κB activity in human skeletal muscle

2012 ◽  
Vol 302 (6) ◽  
pp. R667-R673 ◽  
Author(s):  
Luke Vella ◽  
Marissa K. Caldow ◽  
Amy E. Larsen ◽  
Daniella Tassoni ◽  
Paul A. Della Gatta ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Dna Binding ◽  
Inflammatory Response ◽  
Resistance Exercise ◽  
Muscle Biopsy ◽  
Human Skeletal Muscle ◽  
Control Group ◽  
Promoter Regions ◽  
Protein Levels ◽  
Single Bout

Intense resistance exercise causes a significant inflammatory response. NF-κB has been identified as a prospective key transcription factor mediating the postexercise inflammatory response. The purpose of this study was to determine whether a single bout of intense resistance exercise regulates NF-κB signaling in human skeletal muscle. Muscle biopsy samples were obtained from the vastus lateralis of five recreationally active, but not strength-trained, males (21.9 ± 1.3 yr) prior to, and at 2 and 4 h following, a single bout of intense resistance exercise. A further five subjects (4 males, 1 female) (23 ± 0.89 yr) were recruited as a nonexercise control group to examine the effect of the muscle biopsy protocol on key markers of skeletal muscle inflammation. Protein levels of IκBα and phosphorylated NF-κB (p65), as well as the mRNA expression of inflammatory myokines monocyte chemoattractant protein 1 (MCP-1), IL-6, and IL-8 were measured. Additionally, NF-κB (p65) DNA binding to the promoter regions of MCP-1, IL-6, and IL-8 was investigated. IκBα protein levels decreased, while p-NF-κB (p65) protein levels increased 2 h postexercise and returned to near-baseline levels by 4-h postexercise. Immunohistochemical data verified these findings, illustrating an increase in p-NF-κB (p65) protein levels, and nuclear localization at 2 h postexercise. Furthermore, NF-κB DNA binding to MCP-1, IL-6, and IL-8 promoter regions increased significantly 2 h postexercise as did mRNA levels of these myokines. No significant change was observed in the nonexercise control group. These novel data provide evidence that intense resistance exercise transiently activates NF-κB signaling in human skeletal muscle during the first few hours postexercise. These findings implicate NF-κB in the transcriptional control of myokines known to be central to the postexercise inflammatory response.

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