scholarly journals Skeletal muscle metabolism in sea-acclimatized king penguins. I. Thermogenic mechanisms

2020 ◽  
Vol 223 (21) ◽  
pp. jeb233668
Author(s):  
Damien Roussel ◽  
Marion Le Coadic ◽  
Jean-Louis Rouanet ◽  
Claude Duchamp
Keyword(s):  
Skeletal Muscle ◽  
Muscle Metabolism ◽  
Exact Nature ◽  
Skeletal Muscle Metabolism ◽  
Energy Demands ◽  
Skeletal Muscle Contraction ◽  
Drastic Increase ◽  
Shivering Thermogenesis

ABSTRACTAt fledging, king penguin juveniles undergo a major energetic challenge to overcome the intense and prolonged energy demands for thermoregulation and locomotion imposed by life in cold seas. Among other responses, sea acclimatization triggers fuel selection in skeletal muscle metabolism towards lipid oxidation in vitro, which is reflected by a drastic increase in lipid-induced thermogenesis in vivo. However, the exact nature of skeletal muscle thermogenic mechanisms (shivering and/or non-shivering thermogenesis) remains undefined. The aim of the present study was to determine in vivo whether the capacity for non-shivering thermogenesis was enhanced by sea acclimatization. We measured body temperature, metabolic rate, heart rate and shivering activity in fully immersed king penguins (Aptenodytes patagonicus) exposed to water temperatures ranging from 12 to 29°C. Results from terrestrial pre-fledging juveniles were compared with those from sea-acclimatized immature penguins (hereafter ‘immatures’). The capacity for thermogenesis in water was as effective in juveniles as in immatures, while the capacity for non-shivering thermogenesis was not reinforced by sea acclimatization. This result suggests that king penguins mainly rely on skeletal muscle contraction (shivering or locomotor activity) to maintain endothermy at sea. Sea-acclimatized immature penguins also exhibited higher shivering efficiency and oxygen pulse (amount of oxygen consumed or energy expended per heartbeat) than pre-fledging juvenile birds. Such increase in shivering and cardiovascular efficiency may favor a more efficient activity–thermoregulatory heat substitution providing penguins with the aptitude to survive the tremendous energetic challenge imposed by marine life in cold circumpolar oceans.

In vivo and in vitro characterization of skeletal muscle metabolism in patients with statin-induced adverse effects

2006 ◽  
Vol 55 (4) ◽  
pp. 551-557 ◽  
Author(s):  
S. Guis ◽  
D. Figarella-branger ◽  
J. P. Mattei ◽  
F. Nicoli ◽  
Y. Le Fur ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Adverse Effects ◽  
Muscle Metabolism ◽  
Skeletal Muscle Metabolism ◽  
In Vitro Characterization

scholarly journals Protein kinase N2 regulates AMP kinase signaling and insulin responsiveness of glucose metabolism in skeletal muscle

2017 ◽  
Vol 313 (4) ◽  
pp. E483-E491 ◽  
Author(s):  
Maxwell A. Ruby ◽  
Isabelle Riedl ◽  
Julie Massart ◽  
Marcus Åhlin ◽  
Juleen R. Zierath
Keyword(s):  
Skeletal Muscle ◽  
Protein Kinase ◽  
Glucose Metabolism ◽  
Glucose Uptake ◽  
Muscle Metabolism ◽  
Whole Body ◽  
Skeletal Muscle Metabolism ◽  
Ampk Signaling

Insulin resistance is central to the development of type 2 diabetes and related metabolic disorders. Because skeletal muscle is responsible for the majority of whole body insulin-stimulated glucose uptake, regulation of glucose metabolism in this tissue is of particular importance. Although Rho GTPases and many of their affecters influence skeletal muscle metabolism, there is a paucity of information on the protein kinase N (PKN) family of serine/threonine protein kinases. We investigated the impact of PKN2 on insulin signaling and glucose metabolism in primary human skeletal muscle cells in vitro and mouse tibialis anterior muscle in vivo. PKN2 knockdown in vitro decreased insulin-stimulated glucose uptake, incorporation into glycogen, and oxidation. PKN2 siRNA increased 5′-adenosine monophosphate-activated protein kinase (AMPK) signaling while stimulating fatty acid oxidation and incorporation into triglycerides and decreasing protein synthesis. At the transcriptional level, PKN2 knockdown increased expression of PGC-1α and SREBP-1c and their target genes. In mature skeletal muscle, in vivo PKN2 knockdown decreased glucose uptake and increased AMPK phosphorylation. Thus, PKN2 alters key signaling pathways and transcriptional networks to regulate glucose and lipid metabolism. Identification of PKN2 as a novel regulator of insulin and AMPK signaling may provide an avenue for manipulation of skeletal muscle metabolism.

In vivo 31P MRS study of skeletal muscle metabolism in patients with postpolio residual paralysis

2007 ◽  
Vol 25 (2) ◽  
pp. 244-249 ◽  
Author(s):  
Uma Sharma ◽  
Virendra Kumar ◽  
Sanjay Wadhwa ◽  
Naranamangalan R. Jagannathan
Keyword(s):  
Skeletal Muscle ◽  
Muscle Metabolism ◽  
Residual Paralysis ◽  
Skeletal Muscle Metabolism ◽  
31P Mrs

scholarly journals The Effect of Exercise Training on Myocardial and Skeletal Muscle Metabolism by MR Spectroscopy in Rats with Heart Failure

Metabolites ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 53 ◽  
Author(s):  
Mingshu Shi ◽  
Øyvind Ellingsen ◽  
Tone Bathen ◽  
Morten Høydal ◽  
Tomas Stølen ◽  
...  
Keyword(s):  
Heart Failure ◽  
Skeletal Muscle ◽  
Exercise Training ◽  
Training Session ◽  
Muscle Metabolism ◽  
Principal Component ◽  
Enrichment Analysis ◽  
Metabolic Profiles ◽  
Skeletal Muscle Metabolism

The metabolism and performance of myocardial and skeletal muscle are impaired in heart failure (HF) patients. Exercise training improves the performance and benefits the quality of life in HF patients. The purpose of the present study was to determine the metabolic profiles in myocardial and skeletal muscle in HF and exercise training using MRS, and thus to identify targets for clinical MRS in vivo. After surgically establishing HF in rats, we randomized the rats to exercise training programs of different intensities. After the final training session, rats were sacrificed and tissues from the myocardial and skeletal muscle were extracted. Magnetic resonance spectra were acquired from these extracts, and principal component and metabolic enrichment analysis were used to assess the differences in metabolic profiles. The results indicated that HF affected myocardial metabolism by changing multiple metabolites, whereas it had a limited effect on skeletal muscle metabolism. Moreover, exercise training mainly altered the metabolite distribution in skeletal muscle, indicating regulation of metabolic pathways of taurine and hypotaurine metabolism and carnitine synthesis.

AMP deaminase binding in contracting rat skeletal muscle

1992 ◽  
Vol 263 (2) ◽  
pp. C287-C293 ◽  
Author(s):  
K. W. Rundell ◽  
P. C. Tullson ◽  
R. L. Terjung
Keyword(s):  
Skeletal Muscle ◽  
Iodoacetic Acid ◽  
Amp Deaminase ◽  
Energy Demands ◽  
Slow Twitch Muscle ◽  
Fast Twitch ◽  
Resting Muscle

AMP deaminase, which hydrolyses AMP to inosine 5'-monophosphate (IMP) and NH3 at high rates during excessive energy demands in skeletal muscle, is activated when bound to myosin in vitro. We evaluated AMP deaminase binding in vivo during muscle contractions to assess whether binding 1) is inherent to deamination and found only with high rates of IMP production or simply coincident with the contractile process and 2) requires cellular acidosis. AMP deaminase activity (mumol.min-1.g-1) was measured in the supernatant (free) and 10(4)-g pellet (bound) homogenate fractions of muscle of anesthetized rats after in situ contractions to determine the percent bound. In resting muscle, nearly all (approximately 90%) AMP deaminase is free (cytosolic). During contractions when energy balance was well maintained, binding did not significantly differ from resting values. However, during intense contraction conditions that lead to increased IMP concentration, binding increased to approximately 60% (P less than 0.001) in fast-twitch and approximately 50% in slow-twitch muscle. Binding increased in an apparent first-order manner and preceded initiation of IMP formation. Further, binding rapidly declined within 1 min after cessation of intense stimulation, even though the cell remained extremely acidotic. Extensive binding during contractions was also evident without cellular acidosis (iodoacetic acid-treated muscle). Thus the in vivo AMP deaminase-myosin complex association/dissociation is not coupled to changes in cellular acidosis. Interestingly, binding remained elevated after contractions, if energy recovery was limited by ischemia. Our results are consistent with myosin binding having a role in AMP deaminase activation and subsequent IMP formation in contracting muscle.

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