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Oxidation can decrease or increase the Ca2+ sensitivity of the contractile apparatus in rodent fast-twitch (type II) skeletal muscle fibres, but the reactions and molecular targets involved are unknown. This study examined whether increased Ca2+ sensitivity is due to S-glutathionylation of particular cysteine residues. Skinned muscle fibres were directly(More)
Calsequestrin is a large-capacity Ca-binding protein located in the terminal cisternae of sarcoplasmic reticulum (SR) suggesting a role as a buffer of the concentration of free Ca in the SR ([Ca2+](SR)) serving to maintain the driving force for SR Ca2+ release. Essentially all of the functional studies on calsequestrin to date have been carried out on(More)
The skeletal muscle-specific calpain-3 protease is likely involved in muscle repair, although the mechanism is not known. Physiological activation of calpain-3 occurs 24 h following eccentric exercise in humans. Functional consequences of calpain-3 activation are not known; however, calpain-3 has been suggested to be involved in nuclear signaling via NF-κB.(More)
The Ca(2+) uptake properties of the sarcoplasmic reticulum (SR) were compared between type I and type II fibres of vastus lateralis muscle of young healthy adults. Individual mechanically skinned muscle fibres were exposed to solutions with the free [Ca(2+)] heavily buffered in the pCa range (-log10[Ca(2+)]) 7.3-6.0 for set times and the amount of net SR(More)
The Na(+)-K(+)-ATPase (NKA) plays a key role in muscle excitability, but little is known in human skeletal muscle about fiber-type-specific differences in NKA isoform expression or adaptability. A vastus lateralis muscle biopsy was taken in 17 healthy young adults to contrast NKA isoform protein relative abundance between type I and IIa fibers. We further(More)
One aim of this article was to determine the resting concentration of free Ca(2+) in the sarcoplasmic reticulum (SR) of frog cut skeletal muscle fibers ([Ca(2+)](SR,R)) using the calcium absorbance indicator dye tetramethylmurexide (TMX). Another was to determine the ratio of [Ca(2+)](SR,R) to TMX's apparent dissociation constant for Ca(2+) (K(app)) in(More)
There is considerable interest in potential ergogenic and therapeutic effects of increasing skeletal muscle carnosine content, although its effects on excitation-contraction (EC) coupling in human muscle have not been defined. Consequently, we sought to characterize what effects carnosine, at levels attained by supplementation, has on human muscle fiber(More)
KEY POINTS Muscle weakness in old age is due in large part to an overall loss of skeletal muscle tissue, but it remains uncertain how much also stems from alterations in the properties of the individual muscle fibres. This study examined the contractile properties and amount of stored intracellular calcium in single muscle fibres of Old (70 ± 4 years) and(More)
Whether the use of pre-exercise hyperhydration could improve the performance of athletes who do not hydrate sufficiently during prolonged exercise is still unknown. We therefore compared the effects of pre-exercise hyperhydration and pre-exercise euhydration on endurance capacity, peak power output and selected components of the cardiovascular and(More)
The relationship between sarcoplasmic reticulum (SR) Ca(2+) content and calsequestrin (CSQ) isoforms was investigated in human skeletal muscle. A fibre-lysing assay was used to quantify the endogenous Ca(2+) content and maximal Ca(2+) capacity of the SR in skinned segments of type I and type II fibres from vastus lateralis muscles of young healthy adults.(More)