Unchanged [3H]ouabain binding site content but reduced Na+-K+ pump α2-protein abundance in skeletal muscle in older adults

2012 ◽  
Vol 113 (10) ◽  
pp. 1505-1511 ◽  
Author(s):  
Michael J. McKenna ◽  
Ben D. Perry ◽  
Fabio R. Serpiello ◽  
Marissa K. Caldow ◽  
Pazit Levinger ◽  
...  
Keyword(s):  
Gene Expression ◽  
Skeletal Muscle ◽  
Oxygen Consumption ◽  
Binding Site ◽  
Total Content ◽  
Peak Oxygen Consumption ◽  
Vastus Lateralis Muscle ◽  
Protein Abundance ◽  
Membrane Excitability ◽  
Ouabain Binding

Aging is associated with reduced muscle mass, weakness, and increased fatigability. In skeletal muscle, the Na+-K+ pump (NKA) is important in regulating Na+-K+ gradients, membrane excitability, and thus contractility, but the effects of aging on muscle NKA are unclear. We investigated whether aging is linked with reduced muscle NKA by contrasting muscle NKA isoform gene expression and protein abundance, and NKA total content in 17 Elderly (66.8 ± 6.4 yr, mean ± SD) and 16 Young adults (23.9 ± 2.2 yr). Participants underwent peak oxygen consumption assessment and a vastus lateralis muscle biopsy, which was analyzed for NKA α1-, α2-, α3-, β1-, β2-, and β3-isoform gene expression (real-time RT-PCR), protein abundance (immunoblotting), and NKA total content ([3H]ouabain binding sites). The Elderly had lower peak oxygen consumption (−36.7%, P = 0.000), strength (−36.3%, P = 0.001), NKA α2- (−24.4%, 11.9 ± 4.4 vs. 9.0 ± 2.7 arbitrary units, P = 0.049), and NKA β3-protein abundance (−23.0%, P = 0.041) than Young. The β3-mRNA was higher in Elderly compared with Young ( P = 0.011). No differences were observed between groups for other NKA isoform mRNA or protein abundance, or for [3H]ouabain binding site content. Thus skeletal muscle in elderly individuals was characterized by decreased NKA α2- and β3-protein abundance, but unchanged α1 abundance and [3H]ouabain binding. The latter was likely caused by reduced α2 abundance with aging, preventing an otherwise higher [3H]ouabain binding that might occur with a greater membrane density in smaller muscle fibers. Further study is required to verify reduced muscle NKA α2 with aging and possible contributions to impaired exercise capability and daily living activities.

Sprint training increases human skeletal muscle Na(+)-K(+)-ATPase concentration and improves K+ regulation

1993 ◽  
Vol 75 (1) ◽  
pp. 173-180 ◽  
Author(s):  
M. J. McKenna ◽  
T. A. Schmidt ◽  
M. Hargreaves ◽  
L. Cameron ◽  
S. L. Skinner ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Binding Site ◽  
Intermittent Exercise ◽  
Recovery Period ◽  
Muscle Performance ◽  
Vastus Lateralis Muscle ◽  
Work Output ◽  
Sprint Training ◽  
Ouabain Binding ◽  
Before And After

This study investigated the effects of sprint training on muscle Na(+)-K(+)-adenosinetriphosphatase (ATPase) concentration, plasma [K+] regulation, muscle performance, and fatigue during severe intermittent exercise. Six untrained male subjects underwent intensive cycle-sprint training for 7 wk. Muscle biopsies were taken at rest from the vastus lateralis muscle before and after 7 wk of training and were assayed for Na(+)-K(+)-ATPase concentration using vanadate-facilitated [3H]ouabain binding to intact samples. Before and after the training period, subjects performed four maximal 30-s exercise bouts (EB) on a cycle ergometer, each separated by a 4-min recovery. Arterialized venous blood samples were drawn immediately before and after each sprint bout and were analyzed for plasma [K+]. The work output was significantly elevated (11%) across all four EBs after training. The muscle [3H]ouabain binding site concentration was significantly increased (16%) from 333 +/- 19 to 387 +/- 15 (SE) pmol/g wet wt after training but was unchanged in muscle obtained from three control subjects. Plasma [K+] rose by 1–2 mmol/l with each EB and declined rapidly by the end of each recovery period. The increases in plasma [K+] resulting from each EB were significantly lower (19%) after training. The ratios of rise in plasma [K+] relative to work output during each EB were also significantly lower (27%) after training. The increased muscle [3H]ouabain binding site concentration and the reduced ratio of rise in [K+] relative to work output with exercise are both consistent with improved plasma and skeletal muscle K+ regulation after sprint training.

scholarly journals Effects of exercise on GLUT-4 and glycogenin gene expression in human skeletal muscle

2000 ◽  
Vol 88 (2) ◽  
pp. 794-796 ◽  
Author(s):  
Yorgos Kraniou ◽  
David Cameron-Smith ◽  
Marie Misso ◽  
Greg Collier ◽  
Mark Hargreaves
Keyword(s):  
Gene Expression ◽  
Skeletal Muscle ◽  
Oxygen Consumption ◽  
Human Skeletal Muscle ◽  
Glycogen Synthesis ◽  
Cycle Ergometer ◽  
Peak Oxygen Consumption ◽  
Hexokinase Ii ◽  
Glut 4 ◽  
Single Bout

To investigate the effect of exercise on GLUT-4, hexokinase, and glycogenin gene expression in human skeletal muscle, 10 untrained subjects (6 women and 4 men, 21.4 ± 1.2 yr, 66.3 ± 5.0 kg, peak oxygen consumption = 2.30 ± 0.19 l/min) exercised for 60 min on a cycle ergometer at a power output requiring 73 ± 4% peak oxygen consumption. Muscle samples were obtained by needle biopsy before, immediately after, and 3 h after exercise. Gene expression was quantified, relative to 29S ribosomal protein cDNA, by RT-PCR. GLUT-4 gene expression was increased immediately after exercise (1.7 ± 0.4 vs. 0.9 ± 0.3 arbitrary units; P < 0.05) and remained significantly higher than baseline 3 h after the end of exercise (2.2 ± 0.4 vs. 0.9 ± 0.3 arbitrary units; P < 0.05). Hexokinase II gene expression was significantly higher than the resting value 3 h after the end of exercise (2.9 ± 0.4 vs. 1.3 ± 0.3 arbitrary units; P < 0.05). Exercise increased glycogenin mRNA more than twofold (2.8 ± 0.6 vs. 1.2 ± 0.2 arbitrary units; P < 0.05) 3 h after the end of exercise. For the first time, we report that a single bout of exercise is sufficient to cause upregulation of GLUT-4 and glycogenin gene expression in human skeletal muscle. Whether these increases, together with the associated increase in hexokinase II gene expression, lead to increased expression of these key proteins in skeletal muscle and contribute to the enhanced skeletal muscle glucose uptake, glycogen synthesis, and insulin action observed following exercise remains to be determined.

Impaired muscle Ca2+ and K+ regulation contribute to poor exercise performance post-lung transplantation

2003 ◽  
Vol 95 (4) ◽  
pp. 1606-1616 ◽  
Author(s):  
Michael J. McKenna ◽  
Steve F. Fraser ◽  
Jia L. Li ◽  
Xiao N. Wang ◽  
Michael F. Carey ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Atpase Activity ◽  
Phosphatase Activity ◽  
Vastus Lateralis ◽  
Buffering Capacity ◽  
Peak Oxygen Consumption ◽  
Vastus Lateralis Muscle ◽  
Ouabain Binding ◽  
Potassium Regulation ◽  
Lung Transplant Recipients

Lung transplant recipients (LTx) exhibit marked peripheral limitations to exercise. We investigated whether skeletal muscle Ca2+ and K+ regulation might be abnormal in eight LTx and eight healthy controls. Peak oxygen consumption and arterialized venous plasma [K+] (where brackets denote concentration) were measured during incremental exercise. Vastus lateralis muscle was biopsied at rest and analyzed for sarcoplasmic reticulum Ca2+ release, Ca2+ uptake, and Ca2+-ATPase activity rates; fiber composition; Na+-K+-ATPase (K+-stimulated 3- O-methylfluorescein phosphatase) activity and content ([3H]ouabain binding sites); as well as for [H+] and H+-buffering capacity. Peak oxygen consumption was 47% less in LTx ( P < 0.05). LTx had lower Ca2+ release (34%), Ca2+ uptake (31%), and Ca2+-ATPase activity (25%) than controls ( P < 0.05), despite their higher type II fiber proportion (LTx, 75.0 ± 5.8%; controls, 43.5 ± 2.1%). Muscle [H+] was elevated in LTx ( P < 0.01), but buffering capacity was similar to controls. Muscle 3- O-methylfluorescein phosphatase activity was 31% higher in LTx ( P < 0.05), but [3H]ouabain binding content did not differ significantly. However, during exercise, the rise in plasma [K+]-to-work ratio was 2.6-fold greater in LTx ( P < 0.05), indicating impaired K+ regulation. Thus grossly subnormal muscle calcium regulation, with impaired potassium regulation, may contribute to poor muscular performance in LTx.

scholarly journals Cardiovascular and skeletal muscle health with lifelong exercise

2018 ◽  
Vol 125 (5) ◽  
pp. 1636-1645 ◽  
Author(s):  
Kevin J. Gries ◽  
Ulrika Raue ◽  
Ryan K. Perkins ◽  
Kaleen M. Lavin ◽  
Brittany S. Overstreet ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Oxygen Consumption ◽  
Aerobic Exercise ◽  
Muscle Biopsy ◽  
Citrate Synthase ◽  
Vastus Lateralis ◽  
Metabolic Phenotype ◽  
Vastus Lateralis Muscle ◽  
Metabolic Fitness ◽  
Lifelong Exercise

The purpose of this study was to examine the effects of aerobic lifelong exercise (LLE) on maximum oxygen consumption (V̇o2max) and skeletal muscle metabolic fitness in trained women ( n = 7, 72 ± 2 yr) and men ( n = 21, 74 ± 1 yr) and compare them to old, healthy nonexercisers (OH; women: n = 10, 75 ± 1 yr; men: n = 10, 75 ± 1 yr) and young exercisers (YE; women: n = 10, 25 ± 1 yr; men: n = 10, 25 ± 1 yr). LLE men were further subdivided based on intensity of lifelong exercise and competitive status into performance (LLE-P, n = 14) and fitness (LLE-F, n = 7). On average, LLE exercised 5 day/wk for 7 h/wk over the past 52 ± 1 yr. Each subject performed a maximal cycle test to assess V̇o2maxand had a vastus lateralis muscle biopsy to examine capillarization and metabolic enzymes [citrate synthase, β-hydroxyacyl-CoA dehydrogenase (β-HAD), and glycogen phosphorylase]. V̇o2maxhad a hierarchical pattern (YE > LLE > OH, P < 0.05) for women (44 ± 2 > 26 ± 2 > 18 ± 1 ml·kg−1·min−1) and men (53 ± 3 > 34 ± 1 > 22 ± 1 ml·kg−1·min−1) and was greater ( P < 0.05) in LLE-P (38 ± 1 ml·kg−1·min−1) than LLE-F (27 ± 2 ml·kg−1·min−1). LLE men regardless of intensity and women had similar capillarization and aerobic enzyme activity (citrate synthase and β-HAD) as YE, which were 20%–90% greater ( P < 0.05) than OH. In summary, these data show a substantial V̇o2maxbenefit with LLE that tracked similarly between the sexes, with further enhancement in performance-trained men. For skeletal muscle, 50+ years of aerobic exercise fully preserved capillarization and aerobic enzymes, regardless of intensity. These data suggest that skeletal muscle metabolic fitness may be easier to maintain with lifelong aerobic exercise than more central aspects of the cardiovascular system.NEW & NOTEWORTHY Lifelong exercise (LLE) is a relatively new and evolving area of study with information especially limited in women and individuals with varying exercise intensity habits. These data show a substantial maximal oxygen consumption benefit with LLE that tracked similarly between the sexes. Our findings contribute to the very limited skeletal muscle biopsy data from LLE women (>70 yr), and similar to men, revealed a preserved metabolic phenotype comparable to young exercisers.

scholarly journals Is there a role for sarcolipin in avian facultative thermogenesis in extreme cold?

2020 ◽  
Vol 16 (6) ◽  
pp. 20200078
Author(s):  
Maria Stager ◽  
Zachary A. Cheviron
Keyword(s):  
Gene Expression ◽  
Endoplasmic Reticulum ◽  
Oxygen Consumption ◽  
Heat Generation ◽  
Atp Hydrolysis ◽  
Transcript Abundance ◽  
Peak Oxygen Consumption ◽  
Gene Coding ◽  
Extreme Cold ◽  
Shivering Thermogenesis

Endotherms defend their body temperature in the cold by employing shivering (ST) and/or non-shivering thermogenesis (NST). Although NST is well documented in mammals, its importance to avian heat generation is unclear. Recent work points to a prominent role for the sarco/endoplasmic reticulum Ca 2+ ATPase (SERCA) in muscular NST. SERCA's involvement in both ST and NST, however, posits a tradeoff between these two heat-generating mechanisms. To explore this tradeoff, we assayed pectoralis gene expression of adult songbirds exposed to chronic temperature acclimations. Counter to mammal models, we found that cold-acclimated birds downregulated the expression of sarcolipin ( SLN ), a gene coding for a peptide that promotes heat generation by uncoupling SERCA Ca 2+ transport from ATP hydrolysis, indicating a reduced potential for muscular NST. We also found differential expression of many genes involved in Ca 2+ cycling and muscle contraction and propose that decreased SLN could promote increased pectoralis contractility for ST. Moreover, SLN transcript abundance negatively correlated with peak oxygen consumption under cold exposure (a proxy for ST) across individuals, and higher SLN transcript abundance escalated an individual's risk of hypothermia in acute cold. Our results therefore suggest that SLN-mediated NST may not be an important mechanism of—and could be a hindrance to—avian thermoregulation in extreme cold.

Peak oxygen consumption and skeletal muscle bioenergetics in African-American and Caucasian men

2000 ◽  
Vol 32 (12) ◽  
pp. 2059-2066 ◽  
Author(s):  
RICHARD R. SUMINSKI ◽  
ROBERT J. ROBERTSON ◽  
FREDRIC L. GOSS ◽  
and SILVA ARSLANIAN
Keyword(s):  
Skeletal Muscle ◽  
African American ◽  
Oxygen Consumption ◽  
Peak Oxygen Consumption ◽  
Caucasian Men

Depressed Na+-K+-ATPase activity in skeletal muscle at fatigue is correlated with increased Na+-K+-ATPase mRNA expression following intense exercise

2005 ◽  
Vol 289 (1) ◽  
pp. R266-R274 ◽  
Author(s):  
A. C. Petersen ◽  
K. T. Murphy ◽  
R. J. Snow ◽  
J. A. Leppik ◽  
R. J. Aughey ◽  
...  
Keyword(s):  
Gene Expression ◽  
Atpase Activity ◽  
Mrna Expression ◽  
Binding Sites ◽  
Time Course ◽  
Acute Exercise ◽  
Vastus Lateralis ◽  
Vastus Lateralis Muscle ◽  
Ouabain Binding ◽  
Atpase Gene

We investigated whether depressed muscle Na+-K+-ATPase activity with exercise reflected a loss of Na+-K+-ATPase units, the time course of its recovery postexercise, and whether this depressed activity was related to increased Na+-K+-ATPase isoform gene expression. Fifteen subjects performed fatiguing, knee extensor exercise at ∼40% maximal work output per contraction. A vastus lateralis muscle biopsy was taken at rest, fatigue, 3 h, and 24 h postexercise and analyzed for maximal Na+-K+-ATPase activity via 3- O-methylfluorescein phosphatase (3- O-MFPase) activity, Na+-K+-ATPase content via [3H]ouabain binding sites, and Na+-K+-ATPase α1-, α2-, α3-, β1-, β2- and β3-isoform mRNA expression by real-time RT-PCR. Exercise [352 (SD 267) s] did not affect [3H]ouabain binding sites but decreased 3- O-MFPase activity by 10.7 (SD 8)% ( P < 0.05), which had recovered by 3 h postexercise, without further change at 24 h. Exercise elevated α1-isoform mRNA by 1.5-fold at fatigue ( P < 0.05). This increase was inversely correlated with the percent change in 3- O-MFPase activity from rest to fatigue (%Δ3- O-MFPaserest-fatigue) ( r = −0.60, P < 0.05). The average postexercise (fatigue, 3 h, 24 h) α1-isoform mRNA was increased 1.4-fold ( P < 0.05) and approached a significant inverse correlation with %Δ3- O-MFPaserest-fatigue ( r = −0.56, P = 0.08). Exercise elevated α2-isoform mRNA at fatigue 2.5-fold ( P < 0.05), which was inversely correlated with %Δ3- O-MFPaserest-fatigue ( r = −0.60, P = 0.05). The average postexercise α2-isoform mRNA was increased 2.2-fold ( P < 0.05) and was inversely correlated with the %Δ3- O-MFPaserest-fatigue ( r = −0.68, P < 0.05). Nonsignificant correlations were found between %Δ3- O-MFPaserest-fatigue and other isoforms. Thus acute exercise transiently decreased Na+-K+-ATPase activity, which was correlated with increased Na+-K+-ATPase gene expression. This suggests a possible signal-transduction role for depressed muscle Na+-K+-ATPase activity with exercise.

Effects of adrenal steroids on the concentration of Na+–K+ pumps in rat skeletal muscle

1997 ◽  
Vol 152 (1) ◽  
pp. 49-57 ◽  
Author(s):  
I Dørup ◽  
T Clausen
Keyword(s):  
Skeletal Muscle ◽  
Binding Site ◽  
Binding Sites ◽  
Total Concentration ◽  
Diaphragm Muscle ◽  
Minor Importance ◽  
Adrenal Steroids ◽  
Ouabain Binding ◽  
Old Rats ◽  
High Doses

Abstract Since adrenal steroids have been shown to upregulate the concentration of Na+–K+-ATPase in cardiac muscle, similar effects could be expected in skeletal muscle. Following infusion of dexamethasone (0·02–0·1 mg/kg per day) for 7 days in 10-week-old rats, the total concentration of [3H]ouabain-binding sites rose by up to 22–42% in soleus, extensor digitorum longus, gastrocnemius and diaphragm muscle. Dexamethasone produced no or minute changes in the Na+–K+ contents of skeletal muscle. In contrast, infusion with aldosterone (0·02–0·5 mg/kg per day) for 7 days produced hypokalemia and a graded reduction in the K+ content of skeletal muscle, which was closely correlated to a downregulation of the [3 H]ouabain-binding site concentration (r= 0·65–0·70; P<0·001). The results indicate that in skeletal muscle high doses of glucocorticoids upregulate the concentration of Na+–K+ pumps whereas mineralocorticoids induce a downregulation, which is secondary to the concomitant K+ deficiency. Since adrenalectomy produced no significant change in [3 H]ouabain-binding site concentration, basal levels of endogenous adrenal steroids seem to be of minor importance for the regulation of Na+–K+ pump concentration in skeletal muscle. Journal of Endocrinology (1997) 152, 49–57

scholarly journals Effects of semi-starvation and potassium deficiency on the concentration of [3H]ouabain-binding sites and sodium and potassium contents in rat skeletal muscle

1986 ◽  
Vol 56 (3) ◽  
pp. 519-532 ◽  
Author(s):  
Keld Kjeldsen ◽  
Maria Elisabeth Everts ◽  
Torben Clausen
Keyword(s):  
Skeletal Muscle ◽  
Binding Site ◽  
Soleus Muscle ◽  
Binding Sites ◽  
Total Concentration ◽  
Free Access ◽  
Rat Skeletal Muscle ◽  
Ouabain Binding ◽  
Digitalis Toxicity ◽  
Old Rats

1. Using vanadate-facilitated [3H]ouabain binding, the effect of semi-starvation on the total concentration of [3H]ouabain-binding sites was determined in samples of rat skeletal muscle. When 12-week-old rats were semi-starved for 1, 2 or 3 weeks on one-third to half the normal daily energy intake, the [3H]ouabain-binding site concentration in soleus muscle was reduced by 19, 24 and 25% respectively. In extensor digitorum longus, diaphragm and gastrocnemius muscles the decrease after 2 weeks of semi-starvation was 15, 18 and 17% respectively. The decrease was fully reversible within 3 d of free access to the diet. Complete deprivation of food for 5 d caused a reduction of 25% in soleus muscle [3H]ouabain-binding-siteconcentration. It was excluded that the reduction in [3H]ouabain binding was due to a reduced affinity of the binding site for [3H]ouabain.2. Semi-starvation of 12-week-old rats for 3 weeks caused a reduction of 45 and 53% in 3, 5, 3'-triiodothyronine (T3) and thyroxine (T4) levels respectively. As reduced thyroid hormone levels have previously been found to decrease [3H]ouabain-binding-siteconcentration in skeletal muscle, this points to the importance of T3 and T4 in the down-regulation of the [3H]ouabain-binding-siteconcentration in skeletal muscle with semi-starvation. Whereas potassium depletion caused a decrease in K content as well as in [3H]ouabain-binding-siteconcentration in skeletal muscles, semi-starvation caused only a tendency to a decrease in K content. Thus, K depletion is not a major cause of the reduction in [3H]ouabain-binding-siteconcentration with semi-starvation.3. Due to its high concentration of Na, K pumps, skeletal muscle has a considerable capacity for clearing K from the plasma as well as for the binding of digitalis glycosides. Semi-starvation causes a severe reduction in the total skeletal muscle pool of Na, K pumps and may therefore be associated with impairment of K tolerance and increased digitalis toxicity.

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