Selected Contribution: Acute cellular and molecular responses to resistance exercise

2002 ◽  
Vol 93 (1) ◽  
pp. 394-403 ◽  
Author(s):  
Fadia Haddad ◽  
Gregory R. Adams
Keyword(s):  
Resistance Exercise ◽  
Intracellular Signaling ◽  
Time Course ◽  
Compensatory Hypertrophy ◽  
Molecular Responses ◽  
Single Bout ◽  
And Control ◽  
Myogenic Markers ◽  
Rest Intervals

Training protocols apply sequential bouts of resistance exercise (RE) to induce the cellular and molecular responses necessary to produce compensatory hypertrophy. This study was designed to 1) define the time course of selected cellular and molecular responses to a single bout of RE and 2) examine the effects of interbout rest intervals on the summation of these responses. Rat muscles were exposed to RE via stimulation of the sciatic nerve in vivo. Stimulated and control muscles were obtained at various time points post-RE and analyzed via Western blot and RT-PCR. A single bout of RE increased intracellular signaling (i.e., phosphorylations) and expression of mRNAs for insulin-like growth factor-I system components and myogenic markers (e.g., cyclin D1, myogenin). A rest interval of 48 h between RE bouts resulted in much greater summation of myogenic responses than 24- or 8-h rest intervals. This experimental approach should be useful for studying the regulatory mechanisms that control the hypertrophy response. These methods could also be used to compare and contrast different exercise parameters (e.g., concentric vs. eccentric, etc.).

scholarly journals Hepatic LC3 II/I ratio is not modulated in exercised mice

2020 ◽  
pp. 1103-1111
Author(s):  
B.B. Marafon ◽  
A.P. Pinto ◽  
A.L. Da Rocha ◽  
R.L. Rovina ◽  
J.R. Pauli ◽  
...  
Keyword(s):  
Physical Exercise ◽  
Resistance Exercise ◽  
Time Course ◽  
Normal Cycle ◽  
Purina Chow ◽  
Single Bout ◽  
Different Types ◽  
Exercise Endurance ◽  
Acute Physical Exercise ◽  
Immunoblotting Technique

Autophagy plays an essential role in body homeostasis achievement. One of the main proteins involved in this process is the LC3I, which, after lipidation, leads to the formation of LC3II that participates in the formation and maturation of autophagosome. This descriptive study verified the responses of LC3II to LC3I proteins, as well as the time-course of this ratio in mice livers after different types of acute physical exercise protocols. Eight-week-old male C57BL/6 mice were maintained three per cage with controlled temperature (22±2 °C) on a 12:12-h light-dark normal cycle with food (Purina chow) and water ad libitum. Mice were randomly divided into four groups: control (CT, sedentary mice), resistance (RE, submitted to a single bout of resistance exercise), endurance (EE, submitted to a single bout of endurance exercise), and concurrent (CE, submitted to a single bout of endurance combined with resistance exercise). The mice livers were extracted and used for the immunoblotting technique. The hepatic LC3B II/I ratio for the RE and EE groups were not altered during the different time-points. For the CE group, there was a decrease in this ratio 12h after exercise compared to time 0 and 18h. Also, the hepatic LC3B II/I ratios were not different among the acute physical exercise protocols along the time-course. The hepatic LC3B II/I ratio was not influenced by the endurance and resistance protocols but decreased in response to the concurrent protocol at 12h after the stimulus.

Elevated plasma lactate levels via exogenous lactate infusion do not alter resistance exercise-induced signaling or protein synthesis in human skeletal muscle

2020 ◽  
Vol 319 (4) ◽  
pp. E792-E804
Author(s):  
Rasmus Liegnell ◽  
William Apró ◽  
Sebastian Danielsson ◽  
Björn Ekblom ◽  
Gerrit van Hall ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Resistance Exercise ◽  
Blood Lactate ◽  
Intracellular Signaling ◽  
Recovery Period ◽  
Synthesis Rate ◽  
Protein Synthesis Rate ◽  
Lactate Levels ◽  
The Impact

Lactate has been implicated as a potential signaling molecule. In myotubes, lactate incubation increases mechanistic target of rapamycin complex 1 (mTORC1)- and ERK-signaling and induces hypertrophy, indicating that lactate could be a mediator of muscle adaptations to resistance exercise. However, the potential signaling properties of lactate, at rest or with exercise, have not been explored in human tissue. In a crossover design study, 8 men and 8 women performed one-legged resistance exercise while receiving venous infusion of saline or sodium lactate. Blood was sampled repeatedly, and muscle biopsies were collected at rest and at 0, 90, and 180 min and 24 h after exercise. The primary outcomes examined were intracellular signaling, fractional protein synthesis rate (FSR), and blood/muscle levels of lactate and pH. Postexercise blood lactate concentrations were 130% higher in the Lactate trial (3.0 vs. 7.0 mmol/L, P < 0.001), whereas muscle levels were only marginally higher (27 vs. 32 mmol/kg dry wt, P = 0.003) compared with the Saline trial. Postexercise blood pH was higher in the Lactate trial (7.34 vs. 7.44, P < 0.001), with no differences in intramuscular pH. Exercise increased the phosphorylation of mTORS2448 (∼40%), S6K1T389 (∼3-fold), and p44T202/T204 (∼80%) during recovery, without any differences between trials. FSR over the 24-h recovery period did not differ between the Saline (0.067%/h) and Lactate (0.062%/h) trials. This study does not support the hypothesis that blood lactate levels can modulate anabolic signaling in contracted human muscle. Further in vivo research investigating the impact of exercised versus rested muscle and the role of intramuscular lactate is needed to elucidate its potential signaling properties.

scholarly journals An Experimental Model for Resistance Exercise in Rodents

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Humberto Nicastro ◽  
Nelo Eidy Zanchi ◽  
Claudia Ribeiro da Luz ◽  
Daniela Fojo Seixas Chaves ◽  
Antonio Herbert Lancha
Keyword(s):  
Resistance Exercise ◽  
Energy Restriction ◽  
Exercise Session ◽  
Rest Interval ◽  
Short Term ◽  
Strength Based ◽  
Term Energy ◽  
And Control ◽  
Specific Control

This study aimed to develop an equipment and system of resistance exercise (RE), based on squat-type exercise for rodents, with control of training variables. We developed an operant conditioning system composed of sound, light and feeding devices that allowed optimized RE performance by the animal. With this system, it is not necessary to impose fasting or electric shock for the animal to perform the task proposed (muscle contraction). Furthermore, it is possible to perform muscle function testsin vivowithin the context of the exercise proposed and control variables such as intensity, volume (sets and repetitions), and exercise session length, rest interval between sets and repetitions, and concentric strength. Based on the experiments conducted, we demonstrated that the model proposed is able to perform more specific control of other RE variables, especially rest interval between sets and repetitions, and encourages the animal to exercise through short-term energy restriction and “disturbing” stimulus that do not promote alterations in body weight. Therefore, despite experimental limitations, we believe that this RE apparatus is closer to the physiological context observed in humans.

Test of the paired-flash electroretinographic method in mice lacking b-waves

2007 ◽  
Vol 24 (2) ◽  
pp. 141-149 ◽  
Author(s):  
JENNIFER J. KANG DERWENT ◽  
SHANNON M. SASZIK ◽  
HIDETAKA MAEDA ◽  
DEBORAH M. LITTLE ◽  
MACHELLE T. PARDUE ◽  
...  
Keyword(s):  
Time Course ◽  
Bipolar Cells ◽  
Flash Method ◽  
Peak Time ◽  
Test Flash ◽  
Full Time ◽  
Time Course Data ◽  
And Control ◽  
Rod Response

Previous studies of rod photoreceptors in vivo have employed a paired-flash electroretinographic (ERG) technique to determine rod response properties. To test whether absence versus presence of the ERG b-wave affects the photoreceptor response derived by the paired-flash method, we examined paired-flash-derived responses obtained from nob mice, a mutant strain with a defect in signal transduction between photoreceptors and ON bipolar cells that causes a lack of the b-wave. Normal littermates of the nob mice served as controls. The normalized amplitude-intensity relation of the derived response determined in nob mice at the near-peak time of 86 ms was similar to that determined for the controls. The full time course of the derived rod response was obtained for test flash strengths ranging from 0.11 to 17.38 scotopic cd s m−2 (sc cd s m−2). Time-course data obtained from nob and control mice exhibited significant but generally modest differences. With saturating test flash strengths, half-recovery times for the derived response of nobversus control mice differed by ∼60 ms or less about the combined (nob and control) average respective values. Time course data also were obtained before versus after intravitreal injection of l-2-amino-4-phosphonobutyrate (APB) (which blocks transmission from photoreceptors to depolarizing bipolar cells) and of cis 2,3-piperidine dicarboxylic acid (PDA) (which blocks transmission to OFF bipolar cells, and to horizontal, amacrine and ganglion cells). Neither APB nor PDA substantially affected derived responses obtained from nob or control mice. The results provide quantitative information on the effect of b-wave removal on the paired-flash-derived response in mouse. They argue against a substantial skewing effect of the b-wave on the paired-flash-derived response obtained in normal mice and are consistent with the notion that, to good approximation, this derived response represents the isolated flash response of the photoreceptors in both nob and normal mice.

Time course evaluation of protein synthesis and glucose uptake after acute resistance exercise in rats

2000 ◽  
Vol 88 (3) ◽  
pp. 1142-1149 ◽  
Author(s):  
Jazmir M. Hernandez ◽  
Mark J. Fedele ◽  
Peter A. Farrell
Keyword(s):  
Protein Synthesis ◽  
Resistance Exercise ◽  
Glucose Uptake ◽  
Time Course ◽  
Course Evaluation ◽  
Pi3 Kinase ◽  
Sprague Dawley ◽  
Phosphatidylinositol 3 Kinase ◽  
Sprague Dawley Rats

The temporal pattern for changes in rates of protein synthesis and glucose uptake after resistance exercise, especially relative to each other, is not known. Male Sprague-Dawley rats performed acute resistance exercise ( n = 7) or remained sedentary ( n = 7 per group), and the following were assessed in vivo 1, 3, 6, 12 and 24 h later: rates of protein synthesis, rates of glucose uptake, phosphatidylinositol 3-kinase (PI3-kinase) activity, and p70S6k activity. Rates of protein synthesis in mixed gastrocnemius muscle did not increase until 12 h after exercise (e.g., at 12 h, sedentary = 138 ± 4 vs. exercised = 178 ± 6 nmol phenylalanine incorporated ⋅ g muscle− 1 ⋅ h− 1, mean ± SE, P < 0.05), whereas at 6 h after exercise rates of glucose uptake were significantly elevated (sedentary = 0.18 ± 0.020 vs. exercised = 0.38 ± 0.024 μmol glucose 6-phosphate incorporated ⋅ kg muscle− 1 ⋅ min− 1, P < 0.05). At 24 h after exercise, rates of protein synthesis were still elevated, whereas glucose uptake had returned to basal levels. Arterial insulin concentrations were not different between groups at any time. Non-insulin-stimulated activities of PI3-kinase and p70S6k were higher at 6, 12, and 24 h after exercise ( P < 0.05), and, generally, these occurred when rates of protein synthesis (12 and 24 h) and glucose uptake were elevated (6 and 12 but not 24 h) by exercise. These data suggest that regulators of protein synthesis and glucose uptake may respond to the same contraction-generated signals with different kinetics or that they respond to different intra- or extracellular signals that are generated by exercise.

scholarly journals Time course of molecular responses of human skeletal muscle to acute bouts of resistance exercise

2005 ◽  
Vol 15 (2) ◽  
pp. 135-136 ◽  
Author(s):  
C. S. Bickel ◽  
J. Slade ◽  
E. Mahoney ◽  
F. Haddad ◽  
G. A. Dudley ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Resistance Exercise ◽  
Time Course ◽  
Human Skeletal Muscle ◽  
Molecular Responses

scholarly journals Upregulation of SGLT-1 transport activity in rat jejunum induced by GLP-2 infusion in vivo

1997 ◽  
Vol 273 (6) ◽  
pp. R1965-R1971 ◽  
Author(s):  
C. I. Cheeseman
Keyword(s):  
Intracellular Signaling ◽  
Time Course ◽  
Glucose Transporter ◽  
Membrane Vesicles ◽  
Peptide Hormone ◽  
Affinity Constant ◽  
Glucose Transporter 1 ◽  
Intracellular Signaling Pathway ◽  
Sodium Dependent

The effect of in vivo infusion of the peptide hormone glucagon-like peptide 2 (GLP-2) on glucose transport across the rat jejunal brush-border membrane (BBM) was assessed using isolated membrane vesicles. A 2-h infusion of GLP-2 produced a marked acceleration of sodium-dependent glucose uptake into BBM vesicles with a significant overshoot. There was no change in vesicle space or permeability resulting from the hormone infusion. Kinetic analysis showed this stimulation to be the result of a threefold increase in the maximal rate of transport, with no consistent change in the affinity constant ( K m). The time course of this response showed that the effect was observable, but smaller, after only 30 min of hormone infusion and was maximal after 1 h. Sodium-dependent phloridzin binding to the membrane vesicles showed a parallel increase in maximal binding after 1 and 2 h of hormone infusion. Western blotting showed a similar increase in sodium-dependent glucose transporter 1 (SGLT-1) abundance. The effect of GLP-2 could be blocked by luminal brefeldin A or wortmannin. These results indicate that GLP-2 is able to induce trafficking of SGLT-1 from an intracellular pool into the BBM within 60 min and that phosphoinositol 3-kinase may well be involved in the intracellular signaling pathway in this response.

scholarly journals Cellular and molecular responses to increased skeletal muscle loading after irradiation

2002 ◽  
Vol 283 (4) ◽  
pp. C1182-C1195 ◽  
Author(s):  
Gregory R. Adams ◽  
Vincent J. Caiozzo ◽  
Fadia Haddad ◽  
Kenneth M. Baldwin
Keyword(s):  
Skeletal Muscle ◽  
Skeletal Muscles ◽  
Time Course ◽  
Compensatory Hypertrophy ◽  
Cell Populations ◽  
Molecular Responses ◽  
Time Period ◽  
Muscle Loading ◽  
Stem Cell Populations ◽  
Over Time

Irradiation of rat skeletal muscles before increased loading has been shown to prevent compensatory hypertrophy for periods of up to 4 wk, possibly by preventing satellite cells from proliferating and providing new myonuclei. Recent work suggested that stem cell populations exist that might allow irradiated muscles to eventually hypertrophy over time. We report that irradiation essentially prevented hypertrophy in rat muscles subjected to 3 mo of functional overload (OL-Ir). The time course and magnitude of changes in cellular and molecular markers of anabolic and myogenic responses were similar in the OL-Ir and the contralateral nonirradiated, overloaded (OL) muscles for the first 3–7 days. These markers then returned to control levels in OL-Ir muscles while remaining elevated in OL muscles. The number of myonuclei and amount of DNA were increased markedly in OL but not OL-Ir muscles. Thus it appears that stem cells were not added to the irradiated muscles in this time period. These data are consistent with the theory that the addition of new myonuclei may be required for compensatory hypertrophy in the rat.

Comparison of High Purity Factor IX Concentrates and a Prothrombin Complex Concentrate in a Canine Model of Thrombogenicity

1991 ◽  
Vol 66 (05) ◽  
pp. 609-613 ◽  
Author(s):  
I R MacGregor ◽  
J M Ferguson ◽  
L F McLaughlin ◽  
T Burnouf ◽  
C V Prowse
Keyword(s):  
High Purity ◽  
Time Course ◽  
Prothrombin Complex Concentrate ◽  
Degradation Products ◽  
Canine Model ◽  
Factor Ix ◽  
In Vitro Tests ◽  
Albumin Infusion

SummaryA non-stasis canine model of thrombogenicity has been used to evaluate batches of high purity factor IX concentrates from 4 manufacturers and a conventional prothrombin complex concentrate (PCC). Platelets, activated partial thromboplastin time (APTT), fibrinogen, fibrin(ogen) degradation products and fibrinopeptide A (FPA) were monitored before and after infusion of concentrate. Changes in FPA were found to be the most sensitive and reproducible indicator of thrombogenicity after infusion of batches of the PCC at doses of between 60 and 180 IU/kg, with a dose related delayed increase in FPA occurring. Total FPA generated after 100-120 IU/kg of 3 batches of PCC over the 3 h time course was 9-12 times that generated after albumin infusion. In contrast the amounts of FPA generated after 200 IU/kg of the 4 high purity factor IX products were in all cases similar to albumin infusion. It was noted that some batches of high purity concentrates had short NAPTTs indicating that current in vitro tests for potential thrombogenicity may be misleading in predicting the effects of these concentrates in vivo.

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