Experimental myotonia in mammalian skeletal muscle: Changes in contractile properties

1972 ◽  
Vol 331 (4) ◽  
pp. 315-323 ◽  
Author(s):  
J. Senges ◽  
R. R�del
Keyword(s):  
Skeletal Muscle ◽  
Contractile Properties ◽  
Mammalian Skeletal Muscle ◽  
Muscle Changes

scholarly journals Coupled expression of troponin T and troponin I isoforms in single skeletal muscle fibers correlates with contractility

2006 ◽  
Vol 290 (2) ◽  
pp. C567-C576 ◽  
Author(s):  
Marco A. Brotto ◽  
Brandon J. Biesiadecki ◽  
Leticia S. Brotto ◽  
Thomas M. Nosek ◽  
Jian-Ping Jin
Keyword(s):  
Skeletal Muscle ◽  
Troponin I ◽  
Troponin T ◽  
Muscle Fibers ◽  
Contractile Properties ◽  
Type I ◽  
Myosin Isoforms ◽  
Mammalian Skeletal Muscle ◽  
Single Fibers ◽  
Skeletal Muscle Fibers

Striated muscle contraction is powered by actin-activated myosin ATPase. This process is regulated by Ca2+ via the troponin complex. Slow- and fast-twitch fibers of vertebrate skeletal muscle express type I and type II myosin, respectively, and these myosin isoenzymes confer different ATPase activities, contractile velocities, and force. Skeletal muscle troponin has also diverged into fast and slow isoforms, but their functional significance is not fully understood. To investigate the expression of troponin isoforms in mammalian skeletal muscle and their functional relationship to that of the myosin isoforms, we concomitantly studied myosin, troponin T (TnT), and troponin I (TnI) isoform contents and isometric contractile properties in single fibers of rat skeletal muscle. We characterized a large number of Triton X-100-skinned single fibers from soleus, diaphragm, gastrocnemius, and extensor digitorum longus muscles and selected fibers with combinations of a single myosin isoform and a single class (slow or fast) of the TnT and TnI isoforms to investigate their role in determining contractility. Types IIa, IIx, and IIb myosin fibers produced higher isometric force than that of type I fibers. Despite the polyploidy of adult skeletal muscle fibers, the expression of fast or slow isoforms of TnT and TnI is tightly coupled. Fibers containing slow troponin had higher Ca2+ sensitivity than that of the fast troponin fibers, whereas fibers containing fast troponin showed a higher cooperativity of Ca2+ activation than that of the slow troponin fibers. These results demonstrate distinct but coordinated regulation of troponin and myosin isoform expression in skeletal muscle and their contribution to the contractile properties of muscle.

scholarly journals A Time-Course Comparison of Skeletal Muscle Metabolomic Alterations in Walker-256 Tumour-Bearing Rats at Different Stages of Life

Metabolites ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 404
Author(s):  
Gabriela de Matuoka e Chiocchetti ◽  
Leisa Lopes-Aguiar ◽  
Natália Angelo da Silva Miyaguti ◽  
Lais Rosa Viana ◽  
Carla de Moraes Salgado ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Time Course ◽  
Cancer Cachexia ◽  
Tumour Bearing ◽  
Walker 256 Tumour ◽  
Walker 256 ◽  
Muscle Changes ◽  
The Right ◽  
Biomarker Research ◽  
Host Metabolism

Cancer cachexia is a severe wasting condition that needs further study to find ways to minimise the effects of damage and poor prognosis. Skeletal muscle is the most impacted tissue in cancer cachexia; thus, elucidation of its metabolic alterations could provide a direct clue for biomarker research and be applied to detect this syndrome earlier. In addition, concerning the significant changes in the host metabolism across life, this study aimed to compare the metabolic muscle changes in cachectic tumour-bearing hosts at different ages. We performed 1H-NMR metabolomics in the gastrocnemius muscle in weanling and young adult Walker-256 tumour-bearing rats at different stages of tumour evolution (initial, intermediate, and advanced). Among the 49 metabolites identified, 24 were significantly affected throughout tumour evolution and 21 were significantly affected regarding animal age. The altered metabolites were mainly related to increased amino acid levels and changed energetic metabolism in the skeletal muscle, suggesting an expressive catabolic process and diverted energy production, especially in advanced tumour stages in both groups. Moreover, these changes were more severe in weanling hosts throughout tumour evolution, suggesting the distinct impact of cancer cachexia regarding the host’s age, highlighting the need to adopting the right animal age when studying cancer cachexia.

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