Muscle Na+-K+-ATPase response during 16 h of heavy intermittent cycle exercise

2007 ◽  
Vol 293 (2) ◽  
pp. E523-E530 ◽  
Author(s):  
H. J. Green ◽  
T. A. Duhamel ◽  
G. P. Holloway ◽  
J. W. Moule ◽  
J. Ouyang ◽  
...  
Keyword(s):  
Aerobic Power ◽  
Intermittent Exercise ◽  
Binding Capacity ◽  
Vastus Lateralis ◽  
Intrinsic Activity ◽  
Cycle Exercise ◽  
Maximum Binding Capacity ◽  
Phosphatase Assay ◽  
Quantitative Immunoblotting

This study investigated the effects of a 16-h protocol of heavy intermittent exercise on the intrinsic activity and protein and isoform content of skeletal muscle Na+-K+-ATPase. The protocol consisted of 6 min of exercise performed once per hour at ∼91% peak aerobic power (V̇o2 peak) with tissue sampling from vastus lateralis before (B) and immediately after repetitions 1 (R1), 2 (R2), 9 (R9), and 16 (R16). Eleven untrained volunteers with a V̇o2 peak of 44.3 ± 2.3 ml·kg−1·min−1 participated in the study. Maximal Na+-K+-ATPase activity ( Vmax, in nmol·mg protein−1·h−1) as measured by the 3- O-methylfluorescein K+-stimulated phosphatase assay was reduced ( P < 0.05) by ∼15% with exercise regardless of the number of repetitions performed. In addition, Vmax at R9 and R16 was lower ( P < 0.05) than at R1 and R2. Vanadate-facilitated [3H]ouabain determination of Na+-K+-ATPase content (maximum binding capacity, pmol/g wet wt), although unaltered by exercise, increased ( P < 0.05) 8.3% by R9 with no further increase observed at R16. Assessment of relative changes in isoform abundance measured at B as determined by quantitative immunoblotting showed a 26% increase ( P < 0.05) in the α2-isoform by R2 and a 29% increase in α3 by R9. At R16, β3 was lower ( P < 0.05) than at R2 and R9. No changes were observed in α1, β1, or β2. It is concluded that repeated sessions of heavy exercise, although resulting in increases in the α2- and α3-isoforms and decreases in β3-isoform, also result in depression in maximal catalytic activity.

Rapid upregulation of GLUT-4 and MCT-4 expression during 16 h of heavy intermittent cycle exercise

2008 ◽  
Vol 294 (2) ◽  
pp. R594-R600 ◽  
Author(s):  
H. J. Green ◽  
T. A. Duhamel ◽  
G. P. Holloway ◽  
J. W. Moule ◽  
D. W. Ranney ◽  
...  
Keyword(s):  
Glucose Transporter ◽  
Aerobic Power ◽  
Vastus Lateralis ◽  
Fold Increase ◽  
Monocarboxylate Transporter ◽  
Glycolytic Flux ◽  
Exercise Protocol ◽  
Cycle Exercise ◽  
Muscle Lactate ◽  
Glut 4

In this study, we have investigated the hypothesis that an exercise protocol designed to repeatedly induce a large dependence on carbohydrate and large increases in glycolytic flux rate would result in rapid increases in the principal glucose and lactate transporters in working muscle, glucose transporter (GLUT)-4 and monocarboxylate transporter (MCT)4, respectively, and in activity of hexokinase (Hex), the enzyme used to phosphorylate glucose. Transporter abundance and Hex activity were assessed in homogenates by Western blotting and quantitative chemiluminescence and fluorometric techniques, respectively, in samples of tissue obtained from the vastus lateralis in 12 untrained volunteers [peak aerobic power (V̇o2peak) = 44.3 ± 2.3 ml·kg−1·min−1] before cycle exercise at repetitions 1 (R1), 2 (R2), 9 (R9), and 16 (R16). The 16 repetitions of the exercise were performed for 6 min at ∼90% V̇o2peak, once per hour. Compared with R1, GLUT-4 increased ( P < 0.05) by 28% at R2 and remained elevated ( P < 0.05) at R9 and R16. For MCT-4, increases ( P < 0.05) of 24% were first observed at R9 and persisted at R16. No changes were observed in GLUT-1 and MCT-1 or in Hex activity. The ∼17- to 24-fold increase ( P < 0.05) in muscle lactate observed at R1 and R2 was reduced ( P < 0.05) to an 11-fold increase at R9 and R16. It is concluded that an exercise protocol designed to strain muscle carbohydrate reserves and to result in large increases in lactic acid results in a rapid upregulation of both GLUT-4 and MCT-4.

Dissociation between changes in muscle Na+-K+-ATPase isoform abundance and activity with consecutive days of exercise and recovery

2008 ◽  
Vol 294 (4) ◽  
pp. E761-E767 ◽  
Author(s):  
H. J. Green ◽  
T. A. Duhamel ◽  
R. D. Stewart ◽  
A. R. Tupling ◽  
J. Ouyang
Keyword(s):  
Vastus Lateralis ◽  
Abrupt Onset ◽  
Ouabain Binding ◽  
Tissue Samples ◽  
Atpase Subunit ◽  
Average Decrease ◽  
Subunit Expression ◽  
Powerful Stimulus ◽  
Phosphatase Assay ◽  
Quantitative Immunoblotting

The early plasticity of vastus lateralis Na+-K+-ATPase to the abrupt onset of prolonged submaximal cycling was studied in 12 untrained participants (V̇o2 peak 44.8 ± 2.0 ml·kg−1·min−1, mean ± SE) using a 6-day protocol (3 days of exercise plus 3 days of recovery). Tissue samples were extracted prior to (Pre) and following exercise (Post) on day 1 (E1) and day 3 (E3) and on each day of recovery (R1, R2, R3) and analyzed for changes in maximal protein (βmax) (vanadate-facilitated [3H]ouabain binding), α- and β-isoform concentration (quantitative immunoblotting) and maximal Na+-K+-ATPase activity ( Vmax) (3- O-methylfluorescein K+-stimulated phosphatase assay). For βmax (pmol/g wet wt), an increase ( P < 0.05) of 11.8% was observed at R1 compared with E1-Pre (340 ± 14 vs 304 ± 17). For the α-isoforms α1, α2, and α3, increases ( P < 0.05) of 46, 42, and 31% were observed at R1, respectively. For the β-isoform, β1 and β2 increased ( P < 0.05) by 19 and 28% at R1, whereas β3 increased ( P < 0.05) by 18% at R2. With the exception of α2 and α3, the increases in the isoforms persisted at R3. Exercise resulted in an average decrease ( P < 0.05) in Vmax by 14.3%. No differences were observed in Vmax at E1 - Pre and E3 - Pre or between R1, R2, and R3. It is concluded that 3 days of prolonged exercise is a powerful stimulus for the rapid upregulation of the Na+-K+-ATPase subunit isoforms. Contrary to our hypothesis, the increase in subunit expression is not accompanied by increases in the maximal catalytic activity.

Malleability of human skeletal muscle Na+-K+-ATPase pump with short-term training

2004 ◽  
Vol 97 (1) ◽  
pp. 143-148 ◽  
Author(s):  
H. J. Green ◽  
D. J. Barr ◽  
J. R. Fowles ◽  
S. D. Sandiford ◽  
J. Ouyang
Keyword(s):  
Skeletal Muscle ◽  
Human Skeletal Muscle ◽  
Aerobic Power ◽  
Vastus Lateralis ◽  
Peak Oxygen Consumption ◽  
Rapid Adaptation ◽  
Ouabain Binding ◽  
Short Term ◽  
Power Peak ◽  
Phosphatase Assay

To investigate the hypothesis that short-term submaximal training would result in changes in Na+-K+-ATPase content, activity, and isoform distribution in skeletal muscle, seven healthy, untrained men [peak aerobic power (peak oxygen consumption; V̇o2 peak) = 45.6 ml·kg−1·min−1 (SE 5.4)] cycled for 2 h/day at 60–65% V̇o2 peak for 6 days. Muscle tissue, sampled from the vastus lateralis before training (0 days) and after 3 and 6 days of training and analyzed for Na+-K+-ATPase content, as assessed by the vanadate facilitated [3H]ouabain-binding technique, was increased ( P < 0.05) at 3 days (294 ± 8.6 pmol/g wet wt) and 6 days (308 ± 15 pmol/g wet wt) of training compared with 0 days (272 ± 9.7 pmol/g wet wt). Maximal Na+-K+-ATPase activity as evaluated by the 3- O-methylfluorescein phosphatase assay was increased ( P < 0.05) by 6 days (53.4 ± 5.9 nmol·h−1·mg protein−1) but not by 3 days (35.9 ± 4.5 nmol·h−1·mg protein−1) compared with 0 days (37.8 ± 3.7 nmol·h−1·mg protein−1) of training. Relative isoform distribution, measured by Western blot techniques, indicated increases ( P < 0.05) in α2-content by 3 days and β1-content by 6 days of training. These results indicate that prolonged aerobic exercise represents a potent stimulus for the rapid adaptation of Na+-K+-ATPase content, isoform, and activity characteristics.

Muscle metabolic responses during 16 hours of intermittent heavy exercise

2007 ◽  
Vol 85 (6) ◽  
pp. 634-645 ◽  
Author(s):  
H.J. Green ◽  
T.A. Duhamel ◽  
G.P. Holloway ◽  
J. Moule ◽  
J. Ouyang ◽  
...  
Keyword(s):  
State Transition ◽  
Aerobic Power ◽  
Intermittent Exercise ◽  
Vastus Lateralis ◽  
Muscle Metabolism ◽  
Dry Mass ◽  
Vastus Lateralis Muscle ◽  
Heavy Exercise ◽  
Tissue Samples ◽  
Metabolite Content

The alterations in muscle metabolism were investigated in response to repeated sessions of heavy intermittent exercise performed over 16 h. Tissue samples were extracted from the vastus lateralis muscle before (B) and after (A) 6 min of cycling at approximately 91% peak aerobic power at repetitions one (R1), two (R2), nine (R9), and sixteen (R16) in 13 untrained volunteers (peak aerobic power = 44.3 ± 0.66 mL·kg–1·min–1, mean ± SE). Metabolite content (mmol·(kg dry mass)–1) in homogenates at R1 indicated decreases (p < 0.05) in ATP (21.9 ± 0.62 vs. 17.7 ± 0.68) and phosphocreatine (80.3 ± 2.0 vs. 8.56 ± 1.5) and increases (p < 0.05) in inosine monophosphate (IMP, 0.077 ± 0.12 vs. 3.63 ± 0.85) and lactate (3.80 ± 0.57 vs. 84.6 ± 10.3). The content (µmol·(kg dry mass)–1) of calculated free ADP ([ADPf], 86.4 ± 5.5 vs. 1014 ± 237) and free AMP ([AMPf], 0.32 ± 0.03 vs. 78.4 ± 31) also increased (p < 0.05). No differences were observed between R1 and R2. By R9 and continuing to R16, pronounced reductions (p < 0.05) at A were observed in IMP (72.2%), [ADPf] (58.7%), [AMPf] (85.5%), and lactate (41.3%). The 16-hour protocol resulted in an 89.7% depletion (p < 0.05) of muscle glycogen. Repetition-dependent increases were also observed in oxygen consumption during exercise. It is concluded that repetitive heavy exercise results in less of a disturbance in phosphorylation potential, possibly as a result of increased mitochondrial respiration during the rest-to-work non-steady-state transition.

ENZYMATISCH-FLUOROMETRISCHE BESTIMMUNG DER CORTISOLBINDUNGSKAPAZITÄT DES PLASMA

1967 ◽  
Vol 56 (1) ◽  
pp. 99-106 ◽  
Author(s):  
K. Leybold ◽  
J. Rieper ◽  
L. Weissbecker
Keyword(s):  
Binding Capacity ◽  
Liver Microsomes ◽  
Mean Value ◽  
Female Rats ◽  
Plasma Samples ◽  
Simple Method ◽  
Adult Men ◽  
The Mean ◽  
Precision And Accuracy

ABSTRACT A simple method for the determination of cortisol-binding capacity is described. For saturation of the cortisol-binding proteins, plasma samples are incubated with an excess of cortisol. In the next step NADPH and liver microsomes of female rats are added. The microsomal Δ4-3-ketosteroid hydrogenase only reduces non protein-bound cortisol to tetrahydrocortisol-5α. Then the steroids are extracted by dichloromethane, and after some purification steps analyzed by fluorometry. Tetrahydrocortisol gives practically no fluorescence. The cortisol determined by this method corresponds to protein-bound cortisol and indicates the extent of cortisolbinding capacity. Precision and accuracy of the method were found to be good. The values of cortisol-binding capacity obtained by our method are compared with the results of other authors. The mean value of adult men was 25.5 ± 3.4 μg/100 ml, that of pregnant women, mens IX-X, 42.3 ± 4.2 μg/100 ml.

Determination of maximal aerobic power during upper-body exercise

1983 ◽  
Vol 54 (1) ◽  
pp. 113-117 ◽  
Author(s):  
M. N. Sawka ◽  
M. E. Foley ◽  
N. A. Pimental ◽  
M. M. Toner ◽  
K. B. Pandolf
Keyword(s):  
Heart Rate ◽  
Aerobic Power ◽  
Pulmonary Ventilation ◽  
Maximal Aerobic Power ◽  
Upper Body ◽  
Maximal Heart Rate ◽  
Upper Body Exercise ◽  
Peak Vo2 ◽  
Power Peak

The purpose of this investigation was to evaluate four protocols for their effectiveness in eliciting maximal aerobic power (peak VO2) during arm-crank exercise. Comparisons were made 1) between a continuous (CON) and an intermittent (INT) protocol (both employed a crank rate of 50 rpm) and 2) among the CON protocols employing crank rates of 30, 50, or 70 rpm. For the first group of experiments no significant (P greater than 0.05) differences were found between the CON and INT protocols for peak VO2, maximal pulmonary ventilation (VEmax), maximal heart rate (HRmax), or maximal blood lactate (LAmax) responses. For the second group of experiments, the CON-50 was compared with the CON-30 and CON-70 protocols. In comparison to the CON-50, significantly higher peak VO2 (+10%) and VEmax (+14%) responses were elicited by the CON-70 protocol, whereas significantly lower peak VO2 (-11%), VEmax (-23%), HRmax (-8%), and LAmax (-29%) responses were elicited by the CON-30 protocol. Of the arm-crank protocols examined the combination of a continuous design and a crank rate of 70 rpm provided the most effective protocol to elicit peak VO2 values.

Specific binding of serotonin in rat lung

1985 ◽  
Vol 248 (1) ◽  
pp. E58-E63 ◽  
Author(s):  
D. K. Das ◽  
H. Steinberg
Keyword(s):  
Binding Capacity ◽  
Specific Binding ◽  
Direct Action ◽  
High Capacity ◽  
Mitochondrial Fraction ◽  
Temperature Sensitive ◽  
Inner Mitochondrial Membrane ◽  
High Affinity ◽  
Single Temperature ◽  
Maximum Binding Capacity

Mammalian lungs have been shown to store and to inactivate serotonin (5-HT) by an active process involving uptake and metabolism. 5-HT has direct action on lung including constrictor effects of pulmonary vascular and tracheobronchial smooth muscle, suggesting the presence of 5-HT receptors in lung. We have identified specific 5-HT binding of high affinity to the different lung portions and have shown that there was a different capacity for this binding. Two different 5-HT-binding capacities are present in a purified mitochondrial fraction. Saturation analysis of 5-[3H]HT binding to outer mitochondrial membranes demonstrates a single, temperature-sensitive, high-affinity and high-capacity binding (Kd = 8.3 +/- 1.2 nM, maximum binding capacity = 0.819 +/- 0.046 pmol/mg protein). The dissociation constant of inner mitochondrial membrane demonstrates a low-capacity site (Kd = 25.2 +/- 2.2 nM, maximum binding capacity = 0.453 +/- 0.037 pmol/mg protein). The purified microsomal fraction of lung exhibits a high-capacity binding site for 5-[3H]HT (Kd = 14.8 +/- 1.6 nM, maximum binding capacity = 0.760 +/- 0.03 pmol/mg protein). In addition to the lung being the major site for its inactivation, the presence of several specific 5-HT receptors may be related to some of the known 5-HT actions in lung and may suggest other unknown actions of this amine.

Distribution of opioid receptors in canine small intestine: implications for function

1989 ◽  
Vol 256 (6) ◽  
pp. G966-G974 ◽  
Author(s):  
H. D. Allescher ◽  
S. Ahmad ◽  
P. Kostka ◽  
C. Y. Kwan ◽  
E. E. Daniel
Keyword(s):  
Small Intestine ◽  
Binding Sites ◽  
Myenteric Plexus ◽  
Plasma Membranes ◽  
Binding Capacity ◽  
Opiate Receptors ◽  
Circular Muscle ◽  
Maximum Binding Capacity ◽  
Opiate Binding ◽  
Subtype Selective

Distribution of the binding sites for [3H]diprenorphine, a non-selective opiate ligand, was studied in membrane fractions from longitudinal muscle/myenteric plexus and circular muscle containing deep muscular plexus. [3H]saxitoxin was used as a marker for neuronal plasma membranes and 5'-nucleotidase as a marker for smooth muscle plasma membranes. Saxitoxin binding correlated strongly with diprenorphine binding, but 5'-nucleotidase correlated poorly with diprenorphine or saxitoxin binding in these fractions. Opiate binding sites in membranes of myenteric and deep muscular plexus were of high affinity (Kd = 0.12 and 0.18 nM, respectively) with maximum binding capacity of 400 and 500 fmol/mg protein, respectively. Competition experiments using subtype-selective opiate ligands indicated that all three subtypes of opiate receptors were present in the same ratio of 40-45% mu-subtypes, 40-45% delta-subtypes, and 10-15% kappa-subtypes on both plexuses. Opiate receptors of canine small intestine, therefore, are located primarily or exclusively on nerves with similar distributions in nerve membranes containing only axonal varicosities (deep muscular plexus) as in those containing neurons, dendrites, and varicosities (myenteric plexus).

ATP-MgCl2 treatment after trauma-hemorrhage/resuscitation increases hepatocyte P2-purinoceptor binding capacity

1994 ◽  
Vol 266 (6) ◽  
pp. R1810-R1815
Author(s):  
M. S. Mahmoud ◽  
P. Wang ◽  
S. R. Hootman ◽  
S. S. Reich ◽  
I. H. Chaudry
Keyword(s):  
Binding Capacity ◽  
Scatchard Analysis ◽  
Binding Characteristics ◽  
Beneficial Effects ◽  
High Affinity ◽  
Receptor Component ◽  
Receptor Dynamics ◽  
Maximum Binding Capacity ◽  
High Affinity Receptor ◽  
Affinity Receptor

Although our studies indicate that P2-purinoceptor binding capacity decreases after hemorrhage and resuscitation, it is not known whether ATP-MgCl2 administration after hemorrhage has any beneficial effects on the receptor dynamics. To study this, we performed laparotomy (i.e., trauma induced) on rats and bled them to and maintained them at a mean arterial pressure of 40 mmHg until 40% of maximum bleedout volume was returned in the form of Ringer lactate (RL). The animals were then resuscitated with 3 times the volume of maximum bleedout with RL over 45 min followed by 2 times RL along with ATP-MgCl2 (50 mumol/kg body wt) over 95 min. Hepatocytes were isolated at 4, 17, and 27 h after resuscitation. P2-purinoceptor binding characteristics were determined by using [alpha-35S]ATP. Scatchard analysis revealed high-affinity and low-affinity receptor components in the hepatocytes isolated from sham-operated or hemorrhaged animals with or without ATP-MgCl2 infusion. ATP-MgCl2 ameliorated and subsequently restored the decreased maximum binding capacity (Bmax) of the high-affinity receptor component and significantly improved Bmax of the low-affinity receptor component. ATP-MgCl2 administration also produced a progressive enhancement in the affinity of the low-affinity receptor component. Thus the beneficial effects of ATP-MgCl2 observed after trauma-hemorrhage and resuscitation may be, in part, due to the restoration of P2-purinoceptor binding capacity and the enhancement of the receptor affinity.

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