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Full-Text Articles in Medicine and Health Sciences

No Evidence Of Direct Association Between Glut4 And Glycogen In Human Skeletal Muscle, Robyn M. Murphy, Marcelo Flores-Opazo, Barnaby P. Frankish, Andrew Garnham, David Stapleton, Mark Hargreaves Jan 2018

No Evidence Of Direct Association Between Glut4 And Glycogen In Human Skeletal Muscle, Robyn M. Murphy, Marcelo Flores-Opazo, Barnaby P. Frankish, Andrew Garnham, David Stapleton, Mark Hargreaves

Faculty of Health Sciences Publications

Previous studies have demonstrated that exercise increases whole body and skeletal muscle insulin sensitivity that is linked with increased GLUT4 at the plasma membrane following insulin stimulation and associated with muscle glycogen depletion. To assess the potential direct association between muscle glycogen and GLUT4, seven untrained, male subjects exercised for 60 min at ~75% VO2 peak, with muscle samples obtained by percutaneous needle biopsy immediately before and after exercise. Exercise reduced muscle glycogen content by ~43%. An ultracentrifugation protocol resulted in a ~2‐3‐fold enriched glycogen fraction from muscle samples for analysis. Total GLUT4 content was unaltered by exercise ...


A Novel In Vitro Model For The Assessment Of Postnatal Myonuclear Accretion, Anita Kneppers, Lex B. Verdijk, Chiel De Theije, Mark Corten, Ellis Gielen, Luc Van Loon, Annemie Schols, Ramon Langen Jan 2018

A Novel In Vitro Model For The Assessment Of Postnatal Myonuclear Accretion, Anita Kneppers, Lex B. Verdijk, Chiel De Theije, Mark Corten, Ellis Gielen, Luc Van Loon, Annemie Schols, Ramon Langen

Faculty of Health Sciences Publications

Background: Due to the post-mitotic nature of myonuclei, postnatal myogenesis is essential for skeletal muscle growth, repair, and regeneration. This process is facilitated by satellite cells through proliferation, differentiation, and subsequent fusion with a pre-existing muscle fiber (i.e., myonuclear accretion). Current knowledge of myogenesis is primarily based on the in vitro formation of syncytia from myoblasts, which represents aspects of developmental myogenesis, but may incompletely portray postnatal myogenesis. Therefore, we aimed to develop an in vitro model that better reflects postnatal myogenesis, to study the cell intrinsic and extrinsic processes and signaling involved in the regulation of postnatal myogenesis ...


Exercise And Glut4 In Human Subcutaneous Adipose Tissue, Marcelo Flores-Opazo, Eva Boland, Andrew Garnham, Robyn M. Murphy, Sean L. Mcgee, Mark Hargreaves Jan 2018

Exercise And Glut4 In Human Subcutaneous Adipose Tissue, Marcelo Flores-Opazo, Eva Boland, Andrew Garnham, Robyn M. Murphy, Sean L. Mcgee, Mark Hargreaves

Faculty of Health Sciences Publications

To examine the effect of acute and chronic exercise on adipose tissue GLUT4 expression, a total of 20 healthy, male subjects performed one of two studies. Ten subjects performed cycle ergometer exercise for 60 min at 73 ± 2% VO2 peak and abdominal adipose tissue samples were obtained immediately before and after exercise and after 3 h of recovery. Another 10 subjects completed 10 days of exercise training, comprising a combination of six sessions of 60 min at 75% VO2 peak and four sessions of 6 × 5 min at 90% VO2 peak, separated by 3 min at 40% VO2 peak. Abdominal ...


Muscle Atrophy Due To Nerve Damage Is Accompanied By Elevated Myofibrillar Protein Synthesis Rates, Henning Langer, Joan M. Senden, Annemie P. Gijsen, Stefan Kempa, Luc Van Loon, Simone Spuler Jan 2018

Muscle Atrophy Due To Nerve Damage Is Accompanied By Elevated Myofibrillar Protein Synthesis Rates, Henning Langer, Joan M. Senden, Annemie P. Gijsen, Stefan Kempa, Luc Van Loon, Simone Spuler

Faculty of Health Sciences Publications

Muscle loss is a severe complication of many medical conditions such as cancer, cardiac failure, muscular dystrophies, and nerve damage. The contribution of myofibrillar protein synthesis (MPS) to the loss of muscle mass after nerve damage is not clear. Using deuterium oxide (D2O) labeling, we demonstrate that MPS is significantly increased in rat m. tibialis anterior (TA) compared to control (3.23 ± 0.72 [damaged] to 2.09 ± 0.26%∗day−1 [control]) after 4 weeks of nerve constriction injury. This is the case despite substantial loss of mass of the TA (350 ± 96 mg [damaged] to 946 ± 361 mg ...


Interactive Roles For Ampk And Glycogen From Cellular Energy Sensing To Exercise Metabolism, Natalie Janzen, Jamie Whitfield, Nolan Hoffman Jan 2018

Interactive Roles For Ampk And Glycogen From Cellular Energy Sensing To Exercise Metabolism, Natalie Janzen, Jamie Whitfield, Nolan Hoffman

Faculty of Health Sciences Publications

The AMP-activated protein kinase (AMPK) is a heterotrimeric complex with central roles in cellular energy sensing and the regulation of metabolism and exercise adaptations. AMPK regulatory β subunits contain a conserved carbohydrate-binding module (CBM) that binds glycogen, the major tissue storage form of glucose. Research over the past two decades has revealed that the regulation of AMPK is impacted by glycogen availability, and glycogen storage dynamics are concurrently regulated by AMPK activity. This growing body of research has uncovered new evidence of physical and functional interactive roles for AMPK and glycogen ranging from cellular energy sensing to the regulation of ...