Effects of Acute Exercise on Citrate Synthase Activity as an Aerobic Marker.

Leek, Bryan T.; Mudaliar, Sundar; Richardson, R. S.

doi:10.1097/00005768-199805001-01166

Cited by 2 publications

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“…Our failure to observe an increase in citrate synthase, an enzyme of the CAC, is at odds with two earlier studies that have reported increases in activity following exercise (49,76). In this regard, it is noteworthy that for all of the mitochondrial and cytosolic enzymes measured, with the exception of creatine phosphokinase, there are indications of a transient reductions.…”

Section: Discussioncontrasting

confidence: 99%

Metabolic, enzymatic, and transporter responses in human muscle during three consecutive days of exercise and recovery

Green

Bombardier²,

Duhamel³

et al. 2008

American Journal of Physiology-Regulatory, Integrative and Comp

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AR, Ouyang J. Metabolic, enzymatic, and transporter responses in human muscle during three consecutive days of exercise and recovery. Am J Physiol Regul Integr Comp Physiol 295: R1238 -R1250, 2008. First published July 23, 2008 doi:10.1152/ajpregu.00171.2008This study investigated the responses in substrate-and energy-based properties to repetitive days of prolonged submaximal exercise and recovery. Twelve untrained volunteers (V O 2peak ϭ 44.8 Ϯ 2.0 ml ⅐ kg Ϫ1 ⅐ min Ϫ1 , mean Ϯ SE) cycled (ϳ60 V O2peak) on three consecutive days followed by 3 days of recovery. Tissue samples were extracted from the vastus lateralis both pre-and postexercise on day 1 (E1), day 3 (E3), and during recovery (R1, R2, R3) and were analyzed for changes in metabolism, substrate, and enzymatic and transporter responses. For the metabolic properties (mmol/kg Ϫ1 dry wt), exercise on E1 resulted in reductions (P Ͻ 0.05) in phosphocreatine (PCr; 80 Ϯ 1.9 vs. 41.2 Ϯ 3.0) and increases (P Ͻ 0.05) in inosine monophosphate (IMP; 0.13 Ϯ 0.01 vs. 0.61 Ϯ 0.2) and lactate (3.1 Ϯ 0.4 vs. 19.2 Ϯ 4.3). At E3, both IMP and lactate were lower (P Ͻ 0.05) during exercise. For the transporters, the experimental protocol resulted in a decrease (P Ͻ 0.05) in glucose transporter-1 (GLUT1; 29% by R1), an increase in GLUT4 (29% by E3), and increases (P Ͻ 0.05) for both monocarboxylate transporters (MCT) (for MCT1, 23% by R2 and for MCT4, 18% by R1). Of the mitochondrial and cytosolic enzyme activities examined, cytochrome c oxidase (COX), and hexokinase were both reduced (P Ͻ 0.05) by exercise at E1 and in the case of hexokinase and phosphorylase by exercise on E3. With the exception at COX, which was lower (P Ͻ 0.05) at R1, no differences in enzyme activities existed at rest between E, E3, and recovery days. Results suggest that the glucose and lactate transporters are among the earliest adaptive responses of substrate and metabolic properties studied to the sudden onset of regular lowintensity exercise. contractile activity; glucose; lactate; transporters; vastus lateralis; glycogen; energy metabolism; enzyme activity IN WORKING SKELETAL MUSCLE, regular submaximal contractile activity promotes a better matching between ATP supply and ATP utilization, resulting in less of a disturbance in phosphorylation potential, increased delivery of fuels, such as carbohydrate (CHO) to the metabolic pathways so as not to be limiting to pathway flux, and attenuation of the by-products of metabolism, such as lactic acid, thereby minimizing their potentially disruptive effects (38,39,46,56,68).It has also been reported that these altered responses depend on a series of adaptations that increase the abundance of a multitude of proteins and protein isoforms that are involved in oxidative phosphorylation (OXPHOS), substrate availability, and metabolic by-product management. The tighter metabolic coupling, as an example, has been attributed to the increase in the potential for OXPHOS, which is believed to occur as a result of increases in mitochondrial density and the maximal ac...

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Section: Discussioncontrasting

confidence: 99%

Metabolic, enzymatic, and transporter responses in human muscle during three consecutive days of exercise and recovery

Green

Bombardier²,

Duhamel³

et al. 2008

American Journal of Physiology-Regulatory, Integrative and Comp

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Adaptations in the Muscle Cell to Training: Role of the Na⁺-K⁺-Atpase

Green

2000

Can. J. Appl. Physiol.

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The plasticity of skeletal muscle is evident following the onset of regular contractile activity where extensive adaptations can be observed at all levels of organization. Among the properties subject to altered regulation is the Na+-K+-ATPase, an integral membrane protein distributed throughout the sarcolemma and t-tubule, which functions to maintain high Na+ and K+ transmembrane gradients. This protein is uniquely positioned to control muscle excitation and contraction processes, metabolic flux rates, and contractility. Pronounced and rapid upregulation in the Na+-K+-ATPase content can be observed within the first days of exercise and well before the other major ATPase proteins involved in Ca2+ and actomyosin cycling. Moreover, the Na+-K+-ATPase is subject to complex messenger regulation, involved both in the accommodation and the adaptive responses to contractile activity. This emphasizes that adaptive responses can be mediated soon after the onset of training and may have profound affects on muscle contractility and other cellular adaptations.

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Effects of Acute Exercise on Citrate Synthase Activity as an Aerobic Marker.

Cited by 2 publications

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Metabolic, enzymatic, and transporter responses in human muscle during three consecutive days of exercise and recovery

Metabolic, enzymatic, and transporter responses in human muscle during three consecutive days of exercise and recovery

Adaptations in the Muscle Cell to Training: Role of the Na⁺-K⁺-Atpase

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Effects of Acute Exercise on Citrate Synthase Activity as an Aerobic Marker.

Cited by 2 publications

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Metabolic, enzymatic, and transporter responses in human muscle during three consecutive days of exercise and recovery

Metabolic, enzymatic, and transporter responses in human muscle during three consecutive days of exercise and recovery

Adaptations in the Muscle Cell to Training: Role of the Na+-K+-Atpase

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Adaptations in the Muscle Cell to Training: Role of the Na⁺-K⁺-Atpase