Muscle sarcoplasmic reticulum calcium regulation in humans during consecutive days of exercise and recovery

2007 ◽  
Vol 103 (4) ◽  
pp. 1212-1220 ◽  
Author(s):  
T. A. Duhamel ◽  
R. D. Stewart ◽  
A. R. Tupling ◽  
J. Ouyang ◽  
H. J. Green
Keyword(s):  
Endoplasmic Reticulum ◽  
Sarcoplasmic Reticulum ◽  
Vastus Lateralis ◽  
Phase 1 ◽  
Regular Exercise ◽  
Phase 2 ◽  
Cycle Exercise ◽  
Tissue Samples ◽  
Sustained Reduction ◽  
Sarcoplasmic Reticulum Calcium

The study investigated the hypothesis that three consecutive days of prolonged cycle exercise would result in a sustained reduction in the Ca2+-cycling properties of the vastus lateralis in the absence of changes in the sarcoplasmic (endoplasmic) reticulum Ca2+-ATPase (SERCA) protein. Tissue samples were obtained at preexercise (Pre) and postexercise (Post) on day 1 (E1) and day 3 (E3) and during recovery day 1 (R1), day 2 (R2), and day 3 (R3) in 12 active but untrained volunteers (age 19.2 ± 0.27 yr; mean ± SE) and analyzed for changes (nmol·mg protein−1·min−1) in maximal Ca2+-ATPase activity ( Vmax), Ca2+ uptake and Ca2+ release (phase 1 and phase 2), and SERCA isoform expression (SERCA1a and SERCA2a). At E1, reductions ( P < 0.05) from Pre to Post in Vmax (150 ± 7 vs. 121 ± 7), Ca2+ uptake (7.79 ± 0.28 vs. 5.71 ± 0.33), and both phases of Ca2+ release (phase 1, 20.3 ± 1.3 vs. 15.2 ± 1.1; phase 2, 7.70 ± 0.60 vs. 4.99 ± 0.48) were found. In contrast to Vmax, which recovered at Pre E3 and then remained stable at Post E3 and throughout recovery, Ca2+ uptake remained depressed ( P < 0.05) at E3 Pre and Post and at R1 as did phase 2 of Ca2+ release. Exercise resulted in an increase ( P < 0.05) in SERCA1a (14% at R2) but not SERCA2a. It is concluded that rapidly adapting mechanisms protect Vmax following the onset of regular exercise but not Ca2+ uptake and Ca2+ release.

Malleability of human skeletal muscle sarcoplasmic reticulum to short-term training

2011 ◽  
Vol 36 (6) ◽  
pp. 904-912 ◽  
Author(s):  
Howard J. Green ◽  
Margaret Burnett ◽  
Helen Kollias ◽  
Jing Ouyang ◽  
Ian Smith ◽  
...  
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Aerobic Power ◽  
Vastus Lateralis ◽  
Phase 1 ◽  
Type I ◽  
Phase 2 ◽  
Short Term ◽  
Tissue Samples ◽  
Participant Characteristics ◽  
Training Protocol

This study investigated the hypothesis that adaptations would occur in the sarcoplasmic reticulum in vastus lateralis soon after the onset of aerobic-based training consistent with reduced Ca2+-cycling potential. Tissue samples were extracted prior to (0 days) and following 3 and 6 days of cycling performed for 2 h at 60%–65% of peak aerobic power (VO2peak) in untrained males (VO2peak = 47 ± 2.3 mL·kg–1·min–1; mean ± SE, n = 6) and assessed for changes (nmol·mg protein–1·min–1) in maximal Ca2+-ATPase activity (Vmax), Ca2+-uptake, and Ca2+-release (phase 1 and phase 2) as well as the sarcoplasmic (endoplasmic) reticulum Ca2+-ATPase (SERCA) isoforms. Training resulted in reductions (p < 0.05) in SERCA1a at 6 days (–14%) but not at 3 days. For SERCA2a, reductions (p < 0.05) were also noted only at 6 days (–7%). For Vmax, depressions (p < 0.05) were found at 6 days (172 ± 11) but not at 3 days (176 ± 13; p < 0.10) compared with 0 days (192 ± 11). These changes were accompanied by a lower (p < 0.05) Ca2+-uptake at both 3 days (–39%) and 6 days (–48%). A similar pattern was found for phase 1 Ca2+-release with reductions (p < 0.05) of 37% observed at 6 days and 23% (p = 0.21) at 3 days of training, respectively. In a related study using the same training protocol and participant characteristics, microphotometric determinations of Vmax indicated reductions (p < 0.05) in type I at 3 days (–27%) and at 6 days (–34%) and in type IIA fibres at 6 days (–17%). It is concluded that in response to aerobic-based training, sarcoplasmic reticulum Ca2+-cycling potential is reduced by adaptations that occur soon after training onset.

Muscle sarcoplasmic reticulum Ca2+ cycling adaptations during 16 h of heavy intermittent cycle exercise

2005 ◽  
Vol 99 (3) ◽  
pp. 836-843 ◽  
Author(s):  
G. P. Holloway ◽  
H. J. Green ◽  
T. A. Duhamel ◽  
S. Ferth ◽  
J. W. Moule ◽  
...  
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Atpase Activity ◽  
Vastus Lateralis ◽  
Phase 1 ◽  
Hill Coefficient ◽  
Kinetic Properties ◽  
Cycle Exercise ◽  
Tissue Samples ◽  
The Hill

The repetition-dependent effects of a repetitive heavy exercise protocol previously shown to alter muscle mechanic behavior (Green HJ, Duhamel TA, Ferth S, Holloway GP, Thomas MM, Tupling AR, Rich SM, and Yau JE. J Appl Physiol 97: 2166–2175, 2004) on muscle sarcoplasmic reticulum (SR) Ca2+-transport properties, measured in vitro, were examined in 12 untrained volunteers [peak aerobic power (V̇o2 peak) = 44.3 ± 0.66 ml·kg−1·min−1]. The protocol involved 6 min of cycle exercise performed at ∼91% V̇o2 peak once per hour for 16 h. Tissue samples were obtained from the vastus lateralis before (B) and after (A) exercise at repetitions 1 (R1), 2 (R2), 9 (R9), and 16 (R16). Reductions ( P < 0.05) in maximal Ca2+-ATPase activity ( Vmax) of 26 and 12% with exercise were only observed at R1 and R16, respectively. Vmax remained depressed ( P < 0.05) at R2 (B) but not at R9 (B) and R16 (B). No changes were observed in two other kinetic properties of the enzyme, namely the Hill coefficient (defined as the slope of the relationship between Ca2+-ATPase activity and free Ca2+ concentration) and the Ca50 (defined as the free Ca2+ concentration needed to elicit 50% Vmax). Changes in Ca2+ uptake (measured at 2,000 nM) with exercise and recovery generally paralleled Vmax. The apparent coupling ratio, defined as the ratio between Ca2+ uptake and Vmax, was unaffected by the intermittent protocol. Reductions ( P < 0.05) in phase 1 Ca2+ release (32%) were only observed at R1. No differences were observed between B and A for R2, R9, and R16 or between B and B for R1, R2, R9, and R16. The changes in phase 2 Ca2+ release were as observed for phase 1 Ca2+ release. It is concluded that the SR Ca2+-handling properties, in general, display rapid adaptations to repetitive exercise.

Manipulation of dietary carbohydrates after prolonged effort modifies muscle sarcoplasmic reticulum responses in exercising males

2006 ◽  
Vol 291 (4) ◽  
pp. R1100-R1110 ◽  
Author(s):  
T. A. Duhamel ◽  
J. G. Perco ◽  
H. J. Green
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Muscle Glycogen ◽  
Prolonged Exercise ◽  
Vastus Lateralis ◽  
Phase 1 ◽  
Phase 2 ◽  
Dietary Carbohydrates ◽  
Carbohydrate Diet ◽  
Exercise Induced ◽  
Total Muscle

The hypothesis tested was that disturbances in the sarcoplasmic reticulum (SR) Ca2+-cycling responses to exercise would associate with muscle glycogen reserves. Ten untrained males [peak O2consumption (V̇o2 peak) = 3.41 ± 0.20 (SE) l/min] performed a standardized cycle test (∼70% V̇o2 peak) on two occasions, namely, following 4 days of a high (Hi CHO)- and 4 days of a low (Lo CHO)-carbohydrate diet. Both Hi CHO and Lo CHO were preceded by a session of prolonged exercise designed to deplete muscle glycogen. SR Ca2+cycling in crude homogenates prepared from vastus lateralis samples indicated higher ( P < 0.05) Ca2+uptake (μM·g protein−1·min−1) in Hi CHO compared with Lo CHO at 30 min (2.93 ± 0.10 vs. 2.23 ± 0.12) and at 67 min (2.77 ± 0.16 vs. 2.10 ± 0.12) of exercise, the point of fatigue in Lo CHO. Similar effects ( P < 0.05) were noted between conditions for maximal Ca2+-ATPase (μM·g protein−1·min−1) at 30 min (142 ± 8.5 vs. 107 ± 5.0) and at 67 min (130 ± 4.5 vs. 101 ± 4.7). Both phase 1 and phase 2 Ca2+release were 23 and 37% higher ( P < 0.05) at 30 min of exercise and 15 and 34% higher ( P < 0.05), at 67 min during Hi CHO compared with Lo CHO, respectively. No differences between conditions were observed at rest for any of these SR properties. Total muscle glycogen (mmol glucosyl units/kg dry wt) was higher ( P < 0.05) in Hi CHO compared with Lo CHO at rest (+36%), 30 min (+53%), and at 67 min (+44%) of cycling. These results indicate that exercise-induced reductions in SR Ca2+-cycling properties occur earlier in exercise during low glycogen states compared with high glycogen states.

Effects of prior exercise and a low-carbohydrate diet on muscle sarcoplasmic reticulum function during cycling in women

2006 ◽  
Vol 101 (3) ◽  
pp. 695-706 ◽  
Author(s):  
T. A. Duhamel ◽  
H. J. Green ◽  
J. G. Perco ◽  
J. Ouyang
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Atpase Activity ◽  
Vastus Lateralis ◽  
Phase 1 ◽  
Vastus Lateralis Muscle ◽  
Low Carbohydrate Diet ◽  
Hill Slope ◽  
Low Carbohydrate ◽  
Exercise Induced

The effects of exercise and diet on sarcoplasmic reticulum Ca2+-cycling properties in female vastus lateralis muscle were investigated in two groups of women following four different conditions. The conditions were 4 days of a low-carbohydrate (Lo CHO) and glycogen-depleting exercise plus a Lo CHO diet (Ex + Lo CHO) ( experiment 2) and 4 days of normal CHO (Norm CHO) and glycogen-depleting exercise plus Norm CHO (Ex + Norm CHO) ( experiment 1). Peak aerobic power (V̇o2peak) was 38.1 ± 1.4 (SE); n = 9 and 35.6 ± 1.4 ml·kg−1·min−1; n = 9, respectively. Sarcoplasmic reticulum properties measured in vitro in homogenates (μmol·g protein−1·min−1) indicated exercise-induced reductions ( P < 0.05) in maximal Ca2+-ATPase activity (0 > 30, 60 min > fatigue), Ca2+ uptake (0 > 30 > 60 min, fatigue), and Ca2+ release, both phase 1 (0, 30 > 60 min, fatigue) and phase 2 (0 > 30, 60 min, fatigue; 30 min > fatigue) in Norm CHO. Exercise was without effect in altering the Hill slope ( nH), defined as the slope of relationship between Ca2+-ATPase activity and Ca2+ concentration. No differences were observed between Norm CHO and Ex+Norm CHO. Compared with Norm CHO, Lo CHO resulted in a lower ( P < 0.05) Ca2+ uptake, phase 1 Ca2+ release (30 min), and nH. Ex + Lo CHO resulted in a greater ( P < 0.05) Ca2+ uptake and nH compared with Lo CHO. The results demonstrate that Lo CHO alone can disrupt SR Ca2+ cycling and that, with the exception of Ca2+ release, a glycogen-depleting session of exercise before Lo CHO can reverse the effects.

Hypoxic release of calcium from the sarcoplasmic reticulum of pulmonary artery smooth muscle

2001 ◽  
Vol 281 (2) ◽  
pp. L318-L325 ◽  
Author(s):  
Michelle Dipp ◽  
Piers C. G. Nye ◽  
A. Mark Evans
Keyword(s):  
Smooth Muscle ◽  
Sarcoplasmic Reticulum ◽  
Phase 1 ◽  
Transient Phase ◽  
Phase 2 ◽  
Hypoxic Response ◽  
Pulmonary Vessels ◽  
Intracellular Ca ◽  
Pulmonary Artery Smooth Muscle ◽  
Phase Phase

The hypoxic constriction of isolated pulmonary vessels is composed of an initial transient phase ( phase 1) followed by a slowly developing increase in tone ( phase 2). We investigated the roles of the endothelium and of intracellular Ca2+ stores in both preconstricted and unpreconstricted intrapulmonary rabbit arteries when challenged with hypoxia (Po 2 16–21 Torr). Removing the endothelium did not affect phase 1, but phase 2 appeared as a steady plateau. Removing extracellular Ca2+ had essentially the same effect as removing the endothelium. Depletion of sarcoplasmic reticulum Ca2+stores with caffeine and ryanodine abolished the hypoxic response. Omitting preconstriction reduced the amplitude of the hypoxic response but did not qualitatively affect any of the above responses. We conclude that hypoxia releases intracellular Ca2+ from ryanodine-sensitive stores by a mechanism intrinsic to pulmonary vascular smooth muscle without the need for Ca2+ influx across the plasmalemma or an endothelial factor. Our results also suggest that extracellular Ca2+ is required for the release of an endothelium-derived vasoconstrictor.

Effects of ischemia on sarcoplasmic reticulum Ca2+ uptake and Ca2+ release in rat skeletal muscle

2001 ◽  
Vol 281 (2) ◽  
pp. E224-E232 ◽  
Author(s):  
R. Tupling ◽  
H. Green ◽  
G. Senisterra ◽  
J. Lepock ◽  
N. McKee
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Phase 1 ◽  
Tibialis Anterior Muscle ◽  
Tissue Preparation ◽  
Phase 2 ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Two Phases

In this study, we investigated the hypothesis that prolonged ischemia would impair both sarcoplasmic reticulum (SR) Ca2+ uptake and Ca2+ release in skeletal muscle. To induce total ischemia (I), a tourniquet was placed around the upper hindlimb in 30 female Sprague-Dawley rats [wt = 256 ± 6.7 (SE) g] and inflated to 350 mmHg for 4 h. The contralateral limb served as control (C). Immediately after the 4 h of ischemia, mixed gastrocnemius and tibialis anterior muscle was sampled from both limbs, and both crude muscle homogenates and SR vesicles were prepared. In another 10 control animals (CC), muscles were sampled and prepared exactly the same way, but immediately after anesthetization. Ca2+ uptake and Ca2+ release were measured in vitro with Indo-I on both homogenates and SR vesicles. As hypothesized, submaximal Ca2+ uptake was lower ( P < 0.05) in I compared with CC and C, by 25 and 45% in homogenates and SR vesicles, respectively. Silver nitrate (AgNO3)-induced Ca2+ release, which occurred in two phases ( phase 1 and phase 2), was also altered in I compared with CC and C, in both muscle homogenates and SR vesicles. With ischemia, phase 1 peak Ca2+ release was 26% lower ( P < 0.05) in SR vesicles only. For phase 2, peak Ca2+ release was 54 and 24% lower ( P < 0.05) in SR vesicles and homogenates, respectively. These results demonstrate that prolonged skeletal muscle ischemia leads to a reduced SR Ca2+uptake in both homogenates and SR vesicles. The effects of ischemia on SR Ca2+ release, however, depend on both the phase examined and the type of tissue preparation.

Rationalization and internalization

2001 ◽  
Vol 60 (4) ◽  
pp. 215-230 ◽  
Author(s):  
Jean-Léon Beauvois
Keyword(s):  
Phase 1 ◽  
Facilitatory Effect ◽  
Phase 2 ◽  
Causal Explanations ◽  
Reduction Effect ◽  
Dissonance Reduction

After having been told they were free to accept or refuse, pupils aged 6–7 and 10–11 (tested individually) were led to agree to taste a soup that looked disgusting (phase 1: initial counter-motivational obligation). Before tasting the soup, they had to state what they thought about it. A week later, they were asked whether they wanted to try out some new needles that had supposedly been invented to make vaccinations less painful. Agreement or refusal to try was noted, along with the size of the needle chosen in case of agreement (phase 2: act generalization). The main findings included (1) a strong dissonance reduction effect in phase 1, especially for the younger children (rationalization), (2) a generalization effect in phase 2 (foot-in-the-door effect), and (3) a facilitatory effect on generalization of internal causal explanations about the initial agreement. The results are discussed in relation to the distinction between rationalization and internalization.

PENERAPAN MODEL QUANTUM LEARNING UNTUK MENINGKATKAN HASIL BELAJAR AUTOCAD SISWA KELAS X TEKNIK PEMESINAN SMK NEGERI 1 STABAT

2013 ◽  
Vol 5 (1) ◽  
Author(s):  
Abdul Hasan Saragih
Keyword(s):  
Positive Response ◽  
Phase 1 ◽  
First Grade ◽  
Learning Model ◽  
Second Phase ◽  
Phase 2 ◽  
Phase 3 ◽  
The Third ◽  
Third Phase ◽  
Quantum Learning

This classroom research was conducted on the autocad instructions to the first grade of mechinary class of SMK Negeri 1 Stabat aiming at : (1) improving the student’ archievementon autocad instructional to the student of mechinary architecture class of SMK Negeri 1 Stabat, (2) applying Quantum Learning Model to the students of mechinary class of SMK Negeri 1 Stabat, arising the positive response to autocad subject by applying Quantum Learning Model of the students of mechinary class of SMK Negeri 1 Stabat. The result shows that (1) by applying quantum learning model, the students’ achievement improves significantly. The improvement ofthe achievement of the 34 students is very satisfactory; on the first phase, 27 students passed (70.59%), 10 students failed (29.41%). On the second phase 27 students (79.41%) passed and 7 students (20.59%) failed. On the third phase 30 students (88.24%) passed and 4 students (11.76%) failed. The application of quantum learning model in SMK Negeri 1 Stabat proved satisfying. This was visible from the activeness of the students from phase 1 to 3. The activeness average of the students was 74.31% on phase 1,81.35% on phase 2, and 83.63% on phase 3. (3) The application of the quantum learning model on teaching autocad was very positively welcome by the students of mechinary class of SMK Negeri 1 Stabat. On phase 1 the improvement was 81.53% . It improved to 86.15% on phase 3. Therefore, The improvement ofstudent’ response can be categorized good.

In situ deteriorating patient simulation in general practice

2020 ◽  
Vol 70 (suppl 1) ◽  
pp. bjgp20X711425
Author(s):  
Joanna Lawrence ◽  
Petronelle Eastwick-Field ◽  
Anne Maloney ◽  
Helen Higham
Keyword(s):  
Life Support ◽  
Early Recognition ◽  
Phase 1 ◽  
Patient Simulation ◽  
Medical Emergency ◽  
Phase 2 ◽  
Action Plans ◽  
Integrated Simulation ◽  
Deteriorating Patient

BackgroundGP practices have limited access to medical emergency training and basic life support is often taught out of context as a skills-based event.AimTo develop and evaluate a whole team integrated simulation-based education, to enhance learning, change behaviours and provide safer care.MethodPhase 1: 10 practices piloted a 3-hour programme delivering 40 minutes BLS and AED skills and 2-hour deteriorating patient simulation. Three scenarios where developed: adult chest pain, child anaphylaxis and baby bronchiolitis. An adult simulation patient and relative were used and a child and baby manikin. Two facilitators trained in coaching and debriefing used the 3D debriefing model. Phase 2: 12 new practices undertook identical training derived from Phase 1, with pre- and post-course questionnaires. Teams were scored on: team working, communication, early recognition and systematic approach. The team developed action plans derived from their learning to inform future response. Ten of the 12 practices from Phase 2 received an emergency drill within 6 months of the original session. Three to four members of the whole team integrated training, attended the drill, but were unaware of the nature of the scenario before. Scoring was repeated and action plans were revisited to determine behaviour changes.ResultsEvery emergency drill demonstrated improved scoring in skills and behaviour.ConclusionA combination of: in situ GP simulation, appropriately qualified facilitators in simulation and debriefing, and action plans developed by the whole team suggests safer care for patients experiencing a medical emergency.

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