scholarly journals Effects of tension and stiffness due to reduced pH in mammalian fast- and slow-twitch skinned skeletal muscle fibres.

1990 ◽  
Vol 428 (1) ◽  
pp. 737-750 ◽  
Author(s):  
J M Metzger ◽  
R L Moss
Keyword(s):  
Skeletal Muscle ◽  
Muscle Fibres ◽  
Slow Twitch ◽  
Skeletal Muscle Fibres

scholarly journals Calcium and strontium contractile activation properties of single skinned skeletal muscle fibres from elderly women 66-90 years of age

2021 ◽  
Author(s):  
Sue M Ronaldson ◽  
George D Stephenson ◽  
Stewart I Head
Keyword(s):  
Skeletal Muscle ◽  
Elderly Women ◽  
Vastus Lateralis ◽  
Muscle Fibres ◽  
Vastus Lateralis Muscle ◽  
Type I ◽  
Lateralis Muscle ◽  
Slow Twitch ◽  
Skeletal Muscle Fibres ◽  
Muscle Biopsies

The single skinned muscle fibre technique was used to investigate Ca2+- and Sr2+- activation properties of skeletal muscle fibres from elderly women (66-90 years). Muscle biopsies were obtained from the vastus lateralis muscle. Three populations of muscle fibres were identified according to their specific Sr2+- activation properties: slow-twitch (type I) fast-twitch (type II) and hybrid (type I/II) fibres. All three fibre types were sampled from the biopsies of 66 to 72 years old women, but the muscle biopsies of women older than 80 years yielded only slow-twitch (type I) fibres. The proportion of hybrid fibres in the vastus lateralis muscle of women of circa 70 years of age (24%) was several-fold greater than in the same muscle of adults (<10%), suggesting that muscle remodelling occurs around this age. There were no differences between the Ca2+- and Sr2+- activation properties of slow-twitch fibres from the two groups of elderly women, but there were differences compared with muscle fibres from adults with respect to sensitivity to Ca2+, steepness of the activation curves, and characteristics of the fibre-type dependent phenomenon of spontaneous force oscillations (SOMO) occurring at sub-maximal levels of activation. The maximal Ca2+ activated specific force from all the fibres collected from the seven old women use in the present study was significantly lower by 20% than in the same muscle of adults. Taken together these results show there are qualitative and quantitative changes in the activation properties of the contractile apparatus of muscle fibres from the vastus lateralis muscle of women with advancing age, and that these changes need to be considered when explaining observed changes in womens mobility with aging.

The ascorbic acid transporter SVCT2 is expressed in slow-twitch skeletal muscle fibres

2009 ◽  
Vol 131 (5) ◽  
pp. 565-574 ◽  
Author(s):  
Marcela Low ◽  
Daniel Sandoval ◽  
Evelyn Avilés ◽  
Fernando Pérez ◽  
Francisco Nualart ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Ascorbic Acid ◽  
Muscle Fibres ◽  
Slow Twitch ◽  
Acid Transporter ◽  
Skeletal Muscle Fibres

Myosin isoenzymes in single muscle fibres of Xenopus laevis : analysis of five different functional types

1984 ◽  
Vol 222 (1228) ◽  
pp. 401-408 ◽  
Keyword(s):  
Skeletal Muscle ◽  
Xenopus Laevis ◽  
Muscle Fibres ◽  
Myosin Isoenzymes ◽  
Principal Fibre ◽  
Slow Twitch ◽  
Fast Twitch ◽  
Skeletal Muscle Fibres ◽  
Type 3

An analysis has been performed of the native myosin isoenzyme com position of isolated skeletal muscle fibres from Xenopus laevis with welldefined isotonic contraction properties. Fast twitch ‘ white ’ (type 1) fibres contained three isomyosins; fast twitch ‘red ’ (type 2) fibres showed two major myosin bands with migration velocities very similar to those of the two slower bands in type 1. Slow twitch (type 3) fibres yielded a single, slowly migrating band as did slow tonic (type 5) fibres, whereas the myosin from type 4 (very slow twitch, ‘intermediate’) fibres migrated with a somewhat higher mobility. The results suggest that amphibian skeletal muscle may possess the principal fibre types found in mammals and birds.

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